chore(release): bump version to 0.41.0

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
feat(math): offer the result next to a handwritten = (Issue #46 , stage 3)
2026-10-28 14:48:54 +01:00 · 2026-10-28 14:45:00 +01:00 · 2026-10-28 14:27:25 +01:00 · 2026-10-28 12:34:32 +01:00 · 2026-10-28 08:32:30 +01:00 · 2026-10-28 08:32:30 +01:00
35 changed files with 4716 additions and 642 deletions
@@ -13,10 +13,18 @@ jobs:
    # Standardmäßig 'ubuntu-latest'. Falls Ihr Runner unter einem anderen Label registriert ist
    # (z. B. 'linux', 'ubuntu-24.04' oder 'host'), passen Sie dieses Label an.
    runs-on: ubuntu-latest
    # The APK from the android job goes into the release and its SHA256SUMS.txt
    needs: android
    steps:
      - name: Checkout Repository
        uses: actions/checkout@v4.2.2
      - name: Fetch Android APK
        uses: actions/download-artifact@v4.3.0
        with:
          name: ink-notes-android-apk
          path: target
      - name: Install System Packaging Tools
        run: |
          export DEBIAN_FRONTEND=noninteractive
@@ -63,13 +71,14 @@ jobs:
          cargo clippy --all-targets -- -D warnings
          cargo test
-      - name: Build Release Artifacts (.deb, .AppImage, .exe, SHA256SUMS.txt + .minisig)
+      - name: Build Release Artifacts (.deb, .AppImage, .exe, .apk, SHA256SUMS.txt + .minisig)
        run: |
          chmod +x scripts/*.sh
          ./scripts/build-release.sh
        env:
          MINISIGN_SECRET_KEY: ${{ secrets.MINISIGN_SECRET_KEY }}
          INK_NOTES_REQUIRE_SIGNATURE: "1"
          INK_NOTES_REQUIRE_APK: "1"
      - name: Publish Release to Gitea
        run: |
@@ -79,3 +88,58 @@ jobs:
          GITEA_SERVER: ${{ github.server_url }}
          REPO_OWNER: ${{ github.repository_owner }}
          REPO_NAME: ${{ github.event.repository.name }}
  android:
    # Builds the signed APK (Issue #45) and hands it to the release job as a workflow artifact
    name: Android APK
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Repository
        uses: actions/checkout@v4.2.2
      - name: Install JDK and Tools
        run: |
          export DEBIAN_FRONTEND=noninteractive
          SUDO=""
          if [ "$(id -u)" -ne 0 ] && command -v sudo >/dev/null 2>&1; then
            SUDO="sudo"
          fi
          $SUDO apt-get update -y
          $SUDO apt-get install -y --no-install-recommends \
            openjdk-17-jdk-headless build-essential pkg-config curl unzip zip
      - name: Setup Rust Toolchain
        uses: actions-rust-lang/setup-rust-toolchain@v1.11.0
        with:
          toolchain: stable
          target: aarch64-linux-android
          cache: true
          rustflags: ""
      - name: Cache Android SDK
        uses: actions/cache@v4.2.3
        with:
          path: ~/android-sdk
          key: android-sdk-${{ hashFiles('scripts/setup-android-sdk.sh') }}
      - name: Install Android SDK and NDK
        run: ./scripts/setup-android-sdk.sh
      - name: Build APK
        run: |
          if [ -n "${ANDROID_KEYSTORE_B64}" ]; then
            KEYSTORE="${RUNNER_TEMP:-/tmp}/release.keystore"
            printf '%s' "${ANDROID_KEYSTORE_B64}" | base64 -d > "${KEYSTORE}"
            export ANDROID_KEYSTORE="${KEYSTORE}"
          fi
          ./scripts/package-android.sh
        env:
          ANDROID_KEYSTORE_B64: ${{ secrets.ANDROID_KEYSTORE_B64 }}
          ANDROID_KEYSTORE_PASS: ${{ secrets.ANDROID_KEYSTORE_PASS }}
          ANDROID_KEY_ALIAS: ${{ secrets.ANDROID_KEY_ALIAS }}
      - name: Hand APK to the Release Job
        uses: actions/upload-artifact@v4.6.2
        with:
          name: ink-notes-android-apk
          path: target/ink-notes_*_arm64.apk
@@ -1,3 +1,7 @@
 /target
 *.pdf
 export.pdf
 # Android release signing key, never commit it
 *.keystore
 *.jks
@@ -1540,7 +1540,7 @@ dependencies = [
 [[package]]
 name = "ink-notes"
-version = "0.39.3"
+version = "0.41.0"
 dependencies = [
 "ab_glyph",
 "android_logger",
@@ -1556,6 +1556,7 @@ dependencies = [
 "hayro",
 "hayro-svg",
 "image",
 "jni",
 "log",
 "lopdf",
 "minisign-verify",
@@ -1,6 +1,6 @@
 [package]
 name = "ink-notes"
-version = "0.39.3"
+version = "0.41.0"
 edition = "2021"
 description = "Notizbuch-App für Stift, Touch und Maus unter Linux"
 repository = "https://gitea.pansi.eu/harald/ink-notes"
@@ -73,6 +73,8 @@ wayland-protocols = { version = "0.31", features = ["client", "unstable"] }
 [target.'cfg(target_os = "android")'.dependencies]
 winit = { version = "0.29", features = ["rwh_06", "android-native-activity"] }
 android_logger = { version = "0.13", default-features = false }
 # Saving exports to Downloads through Android's MediaStore
 jni = { version = "0.21", default-features = false }
 log = "0.4"
 [package.metadata.android]
@@ -13,7 +13,7 @@
 ink-notes speichert Handschrift als Vektoren, erkennt auf Wunsch Formen, kann PDFs zum Beschriften sowie Notizbücher aus Xournal++, Rnote und Saber importieren, Bilder und Textfelder einfügen und alles wieder als PDF, PNG oder SVG exportieren. Gespeichert wird automatisch im Hintergrund.
-Getestet wird vor allem unter Zorin OS 18 / Ubuntu 24.04 (Wayland und X11). Eine Windows-Version gibt es als experimentelles portables Programm.
+Getestet wird vor allem unter Zorin OS 18 / Ubuntu 24.04 (Wayland und X11). Eine Windows-Version gibt es als experimentelles portables Programm, eine Android-Version als APK.
 Die Oberfläche gibt es auf Deutsch und Englisch; ink-notes folgt der Systemsprache, umstellen lässt sie sich im ☰-Menü unter „Sprache / Language“.
@@ -37,6 +37,11 @@ Die Oberfläche gibt es auf Deutsch und Englisch; ink-notes folgt der Systemspra
 - Erkannt werden Linien, Pfeile, Kreise, Ellipsen, Rechtecke, Dreiecke, Rauten, Vielecke, Koordinatensysteme (L-Form), Achsenkreuze (ein „+“ in einem Zug oder zwei gekreuzte Geraden, Pfeilspitzen an allen vier Enden) und Oktaeder (Skizze als 3D-Körper).
 - Die Erkennung arbeitet rein geometrisch (Bogenlänge, Douglas-Peucker, Kreis-Fit), ohne Machine Learning. Nicht alles wird erkannt – was nicht passt, bleibt Handschrift.
 ### Formeln ausrechnen (experimentell)
 - Einschalten im ☰-Menü unter Eingabe („Formeln nach „=“ ausrechnen“). Nach einem handgeschriebenen `=` und einer kurzen Pause erscheint daneben das Ergebnis samt dem Gelesenen, z. B. `2⁴ = 16` oder `(x + 3)² = x² + 6x + 9`; Antippen mit dem Stift oder Klicken fügt es als Textfeld in der Stiftfarbe und in der Höhe der Handschrift ein (Rückgängig entfernt es). Finger und Handballen lösen nichts aus.
 - Gelesen werden Ziffern, `+ − · : /`, Klammern, Hochzahlen (hochgestellt geschrieben), Bruchstriche, Dezimalkommas und die Variablen `x`, `y`, `a`, `b`. Zahlen werden exakt als Brüche gerechnet, Ausdrücke mit Variablen ausmultipliziert. Vor der Formel etwas Abstand lassen, damit weiter links Geschriebenes nicht mitgelesen wird; in einer Kette wie `x = 2 · 3 =` wird der Teil nach dem vorigen `=` gerechnet.
 - Die Zeichen werden mit Punktwolken-Vorlagen ($P) erkannt, ohne Machine Learning und offline. Zeigt der Vorschlag ein falsches Zeichen, ihn einfach ignorieren.
 ### Auswählen und Bearbeiten
 - **Auswahlwerkzeug** (`V`): antippen oder Rahmen aufziehen, dann verschieben, an den Ecken skalieren, am Griff drehen oder mit `R` um 90° drehen. Funktioniert mit Maus, Finger und Stift.
 - Auswahl über die Palette **umfärben**, **kopieren/einfügen** (`Strg + C/V`), **löschen** (`Entf`).
@@ -87,7 +92,7 @@ Die Oberfläche gibt es auf Deutsch und Englisch; ink-notes folgt der Systemspra
 ## Installation
-Pakete gibt es unter [Releases](https://gitea.pansi.eu/harald/ink-notes/releases) als `.deb`, `.AppImage` und für Windows als `.exe` (x86_64). `<version>` steht für die Versionsnummer, z. B. `0.11.0`.
+Pakete gibt es unter [Releases](https://gitea.pansi.eu/harald/ink-notes/releases) als `.deb`, `.AppImage`, für Windows als `.exe` (x86_64) und für Android als `.apk` (arm64). `<version>` steht für die Versionsnummer, z. B. `0.11.0`.
 ```bash
 # Debian-Paket (Zorin OS 18 / Ubuntu 24.04)
@@ -104,6 +109,8 @@ Hinweise:
 **Windows (experimentell):** `ink-notes_<version>_x86_64.exe` ist ein portables Programm für Windows 10/11 – ohne Installation einfach starten (Windows SmartScreen fragt evtl. einmal nach, da das Programm nicht signiert ist). Stifteingabe mit Druck läuft über Windows Ink (noch nicht auf echter Hardware getestet). Notizbücher und Einstellungen liegen in `%APPDATA%\ink-notes`. Updates ersetzen die `.exe` an Ort und Stelle und gelten ab dem nächsten Start.
 **Android:** `ink-notes_<version>_arm64.apk` läuft ab Android 8 (64-Bit-ARM). Auf dem Gerät herunterladen und öffnen; Android fragt einmal, ob Browser oder Dateimanager Apps installieren dürfen. Der Stift wird von Fingern unterschieden (Stifttasten, Radierer-Ende, Handballen-Erkennung), Import und „Bild einfügen“ nutzen den System-Dateidialog, und Exporte landen in `Download/ink-notes` (ab Android 10). Notizbücher liegen im eigenen Speicher der App und werden beim Deinstallieren gelöscht – vorher exportieren, was bleiben soll. Ein Update in der App gibt es nicht: die neue APK über die alte installieren, die Notizbücher bleiben erhalten.
 ---
 ## Tastenkürzel
@@ -156,7 +163,7 @@ Die CI prüft zusätzlich `cargo fmt --check` und `cargo clippy --all-targets --
 Andere Systeme:
 - **Windows** wird unter Linux übersetzt: `scripts/package-windows.sh` (braucht `gcc-mingw-w64-x86-64`); die Tests laufen mit `wine` als Runner (`CARGO_TARGET_X86_64_PC_WINDOWS_GNU_RUNNER=wine cargo test --target x86_64-pc-windows-gnu`).
- **Android** (experimentell, Issue #42): `scripts/package-android.sh` baut `target/ink-notes_<version>_arm64.apk` ohne Gradle. Nötig sind das Android-SDK (build-tools, Plattform 34; `ANDROID_HOME`, Standard `~/android-sdk`) und das NDK; der Signierschlüssel kommt aus `ANDROID_KEYSTORE`, `ANDROID_KEYSTORE_PASS` und `ANDROID_KEY_ALIAS`, sonst wird der Debug-Schlüssel verwendet. Installieren mit `adb install -r target/ink-notes_<version>_arm64.apk`, Log-Ausgaben mit `adb logcat -s ink-notes`. Notizbücher bleiben vorerst in der App; Stifterkennung, Bildschirmtastatur und Dateidialoge fehlen noch.
+- **Android** (Issue #42): `scripts/package-android.sh` baut `target/ink-notes_<version>_arm64.apk` ohne Gradle. Nötig sind das Android-SDK (build-tools, Plattform 34; `ANDROID_HOME`, Standard `~/android-sdk`) und das NDK; der Signierschlüssel kommt aus `ANDROID_KEYSTORE`, `ANDROID_KEYSTORE_PASS` und `ANDROID_KEY_ALIAS`, sonst wird der Debug-Schlüssel verwendet. Ohne SDK auf dem Rechner baut `scripts/build-apk-container.sh` sie in einem Container (podman oder docker, `packaging/android/Containerfile`); `scripts/setup-android-sdk.sh` installiert die festen SDK-/NDK-Versionen. Der CI-Job `android` baut die APK zu jedem Release und legt sie ins Release und in `SHA256SUMS.txt`; der Release-Schlüssel gehört in die Secrets `ANDROID_KEYSTORE_B64` (`base64 -w0 release.keystore`), `ANDROID_KEYSTORE_PASS` und `ANDROID_KEY_ALIAS`. Installieren mit `adb install -r target/ink-notes_<version>_arm64.apk`, Log-Ausgaben mit `adb logcat -s ink-notes`. Der Stift wird von Fingern unterschieden (Stifttasten, Radierer-Ende, Handballen-Erkennung), Textfelder öffnen die Bildschirmtastatur, Import und „Bild einfügen“ nutzen den System-Dateidialog, und Exporte landen in `Download/ink-notes` (ab Android 10). Tastaturtext und Dateidialog kommen von der kleinen Java-Activity `packaging/android/java/…/InkActivity.java` (zum Bauen ist ein JDK nötig).
 ### Projektstruktur
@@ -189,6 +196,9 @@ src/
 ├── storage.rs      # Laden/Speichern (atomar), Notizbücher, Papierkorb, Speicherort
 ├── disk_watch.rs   # Änderungen anderer Geräte übernehmen (Sync-Clients)
 ├── library.rs      # Ordner der Notizbücher (library.json)
 ├── math.rs         # Exaktes Ausrechnen handgeschriebener Formeln (Issue #46)
 ├── math_ink.rs     # Erkennung handgeschriebener Formeln ($P-Punktwolken)
 ├── math_assist.rs  # Ergebnis neben einem handgeschriebenen „=“ (Auslöser, Vorschlag)
 ├── autosave.rs     # Speichern im Hintergrund
 ├── export.rs       # PDF-Export
 ├── page_export.rs  # Seite als PNG/SVG, Auswahl als Bild
@@ -13,7 +13,7 @@
 ink-notes stores handwriting as vectors, can recognize shapes, imports PDFs for annotation as well as Xournal++, Rnote and Saber notebooks, inserts images and text boxes, and exports everything again as PDF, PNG or SVG. Saving happens automatically in the background.
-It is mainly tested on Zorin OS 18 / Ubuntu 24.04 (Wayland and X11). A Windows version is available as an experimental portable program.
+It is mainly tested on Zorin OS 18 / Ubuntu 24.04 (Wayland and X11). A Windows version is available as an experimental portable program, and an Android version as an APK.
 The interface is available in English and German; ink-notes follows the system language, and you can switch it in the ☰ menu under "Sprache / Language".
@@ -37,6 +37,11 @@ The interface is available in English and German; ink-notes follows the system l
 - Recognized shapes: lines, arrows, circles, ellipses, rectangles, triangles, rhombuses, polygons, coordinate systems (L shape), axis crosses (a "+" in one stroke or two crossing straight lines, arrowheads on all four ends) and octahedra (sketch as a 3D solid).
 - Recognition is purely geometric (arc length, Douglas-Peucker, circle fitting), without machine learning. Not everything is recognized – whatever does not fit stays handwriting.
 ### Computing formulas (experimental)
 - Turn on in the ☰ menu under input ("Compute formulas after “=”"). After a handwritten `=` and a short pause, the result appears next to it together with what was read, e.g. `2⁴ = 16` or `(x + 3)² = x² + 6x + 9`; tapping it with the pen or clicking inserts it as a text box in the ink color, as high as the handwriting (undo removes it). Fingers and palms do not trigger it.
 - Read are digits, `+ − · : /`, parentheses, exponents (written raised), fraction bars, decimal commas and the variables `x`, `y`, `a`, `b`. Numbers are computed exactly as fractions, expressions with variables are multiplied out. Leave some space before the formula, so that writing further to the left is not read with it; in a chain such as `x = 2 · 3 =` the part after the previous `=` is computed.
 - The symbols are recognized with point-cloud templates ($P), without machine learning and offline. If the suggestion shows a wrong symbol, just ignore it.
 ### Selecting and editing
 - **Selection tool** (`V`): tap or drag a frame, then move, scale by the corners, rotate by the handle, or rotate by 90° with `R`. Works with mouse, finger and pen.
 - **Recolor** the selection with the palette, **copy/paste** (`Ctrl + C/V`), **delete** (`Del`).
@@ -87,7 +92,7 @@ The interface is available in English and German; ink-notes follows the system l
 ## Installation
-Packages are available under [Releases](https://gitea.pansi.eu/harald/ink-notes/releases) as `.deb`, `.AppImage` and for Windows as `.exe` (x86_64). `<version>` stands for the version number, e.g. `0.30.2`.
+Packages are available under [Releases](https://gitea.pansi.eu/harald/ink-notes/releases) as `.deb`, `.AppImage`, for Windows as `.exe` (x86_64) and for Android as `.apk` (arm64). `<version>` stands for the version number, e.g. `0.30.2`.
 ```bash
 # Debian package (Zorin OS 18 / Ubuntu 24.04)
@@ -104,6 +109,8 @@ Notes:
 **Windows (experimental):** `ink-notes_<version>_x86_64.exe` is a portable program for Windows 10/11 – no installation, just start it (Windows SmartScreen may ask once, as the program is not signed). Pen input with pressure uses Windows Ink (not yet tested on real hardware). Notebooks and settings are stored in `%APPDATA%\ink-notes`. Updates replace the `.exe` in place and take effect at the next start.
 **Android:** `ink-notes_<version>_arm64.apk` runs on Android 8 and newer (64-bit ARM). Download it on the device and open it; Android asks once to allow installing apps from the browser or file manager. The pen is told apart from fingers (pen buttons, eraser end, palm rejection), import and inserting images use the system file dialog, and exports are saved to `Download/ink-notes` (Android 10 and newer). Notebooks are stored in the app's own storage and are removed when the app is uninstalled – export what you want to keep first. There is no in-app update: install the new APK over the old one, the notebooks stay.
 ---
 ## Keyboard shortcuts
@@ -156,7 +163,7 @@ CI additionally checks `cargo fmt --check` and `cargo clippy --all-targets -- -D
 Other systems:
 - **Windows** is cross-compiled on Linux: `scripts/package-windows.sh` (needs `gcc-mingw-w64-x86-64`); the tests run with `wine` as runner (`CARGO_TARGET_X86_64_PC_WINDOWS_GNU_RUNNER=wine cargo test --target x86_64-pc-windows-gnu`).
- **Android** (experimental, Issue #42): `scripts/package-android.sh` builds `target/ink-notes_<version>_arm64.apk` without Gradle. It needs the Android SDK (build-tools, platform 34; `ANDROID_HOME`, default `~/android-sdk`) and the NDK; the signing key comes from `ANDROID_KEYSTORE`, `ANDROID_KEYSTORE_PASS` and `ANDROID_KEY_ALIAS`, otherwise the debug key is used. Install with `adb install -r target/ink-notes_<version>_arm64.apk`, log output with `adb logcat -s ink-notes`. Notebooks stay inside the app for now; pen detection, on-screen keyboard and file dialogs are still missing.
+- **Android** (Issue #42): `scripts/package-android.sh` builds `target/ink-notes_<version>_arm64.apk` without Gradle. It needs the Android SDK (build-tools, platform 34; `ANDROID_HOME`, default `~/android-sdk`) and the NDK; the signing key comes from `ANDROID_KEYSTORE`, `ANDROID_KEYSTORE_PASS` and `ANDROID_KEY_ALIAS`, otherwise the debug key is used. Without SDK on the host, `scripts/build-apk-container.sh` builds it in a container (podman or docker, `packaging/android/Containerfile`); `scripts/setup-android-sdk.sh` installs the fixed SDK/NDK versions. The CI job `android` builds the APK for every release and adds it to the release and to `SHA256SUMS.txt`; the release key goes into the secrets `ANDROID_KEYSTORE_B64` (`base64 -w0 release.keystore`), `ANDROID_KEYSTORE_PASS` and `ANDROID_KEY_ALIAS`. Install with `adb install -r target/ink-notes_<version>_arm64.apk`, log output with `adb logcat -s ink-notes`. The pen is told apart from fingers (pen buttons, eraser end, palm rejection), text fields open the soft keyboard, import and inserting images use the system file dialog, and exports are saved to `Download/ink-notes` (Android 10 and newer). The small Java activity `packaging/android/java/…/InkActivity.java` (needs a JDK to build) provides keyboard text and the file dialog.
 New code comments and commit messages are written in English; older code and history still contain German.
@@ -191,6 +198,9 @@ src/
 ├── storage.rs      # Loading/saving (atomic), notebooks, trash, storage location
 ├── disk_watch.rs   # Taking over changes from other devices (sync clients)
 ├── library.rs      # Notebook folders (library.json)
 ├── math.rs         # Exact evaluation of handwritten math (Issue #46)
 ├── math_ink.rs     # Recognition of handwritten math ($P point clouds)
 ├── math_assist.rs  # Result next to a handwritten "=" (trigger, suggestion)
 ├── autosave.rs     # Saving in the background
 ├── export.rs       # PDF export
 ├── page_export.rs  # Page as PNG/SVG, selection as image
@@ -19,6 +19,12 @@
      <stop offset="100%" stop-color="#38bdf8" stop-opacity="0"/>
    </radialGradient>
    <!-- Highlight Card Gradient -->
    <linearGradient id="highlightGrad" x1="0%" y1="0%" x2="100%" y2="100%">
      <stop offset="0%" stop-color="#132644"/>
      <stop offset="100%" stop-color="#0d1b32"/>
    </linearGradient>
    <!-- Icon Hintergrund-Verlauf -->
    <linearGradient id="bgGrad" x1="0%" y1="0%" x2="100%" y2="100%">
      <stop offset="0%" stop-color="#1e2638"/>
@@ -121,58 +127,98 @@
  <!-- ==================== RECHTER BEREICH: TYPOGRAFIE & BADGES ==================== -->
  <g transform="translate(360, 0)">
-    <!-- Version & Platform Pill -->
+    <!-- Top Badges -->
-    <g transform="translate(0, 68)">
+    <g transform="translate(0, 56)">
-      <rect width="214" height="30" rx="15" fill="#1e293b" stroke="#334155" stroke-width="1.2"/>
+      <!-- Platform Pill (No version number) -->
-      <circle cx="16" cy="15" r="4" fill="#22c55e"/>
+      <rect width="248" height="28" rx="14" fill="#1e293b" stroke="#334155" stroke-width="1.2"/>
-      <text x="28" y="20" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="600" fill="#cbd5e1" letter-spacing="0.5">
+      <circle cx="15" cy="14" r="4" fill="#22c55e"/>
-        LINUX • RUST &amp; WGPU
+      <text x="27" y="18.5" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="12" font-weight="600" fill="#cbd5e1" letter-spacing="0.6">
        LINUX • WINDOWS • ANDROID
      </text>
      <!-- Engine Pill -->
      <g transform="translate(260, 0)">
        <rect width="138" height="28" rx="14" fill="#1e293b" stroke="#334155" stroke-width="1.2"/>
        <text x="13" y="18.5" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="11.5" font-weight="600" fill="#94a3b8" letter-spacing="0.5">
          ⚡ RUST &amp; WGPU
        </text>
      </g>
      <!-- Major Update Pill -->
      <g transform="translate(410, 0)">
        <rect width="144" height="28" rx="14" fill="url(#highlightGrad)" stroke="#0ea5e9" stroke-width="1.2"/>
        <circle cx="15" cy="14" r="3.5" fill="#38bdf8"/>
        <text x="27" y="18.5" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="11.5" font-weight="700" fill="#38bdf8" letter-spacing="0.5">
          MAJOR UPDATE
        </text>
      </g>
    </g>
    <!-- Haupttitel: ink-notes -->
-    <text x="0" y="162" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="800" font-size="64" letter-spacing="-1">
+    <text x="0" y="140" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="800" font-size="58" letter-spacing="-1">
      <tspan fill="url(#textInkGrad)">ink</tspan><tspan fill="#f8fafc">-notes</tspan>
    </text>
    <!-- Subtitle / Tagline -->
-    <text x="0" y="206" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="400" font-size="22" fill="#94a3b8">
+    <text x="0" y="178" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="400" font-size="20" fill="#94a3b8">
      Notebook &amp; PDF annotation app for pen, touch and mouse
    </text>
-    <!-- Feature Pills / Highlights -->
+    <!-- Feature Highlights: Row 1 (Brand New Major Changes) -->
-    <g transform="translate(0, 248)">
+    <g transform="translate(0, 214)">
-      <!-- Pill 1: Niedrige Latenz -->
+      <!-- Pill 1: Windows & Android Support -->
      <g transform="translate(0, 0)">
-        <rect width="152" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="250" height="36" rx="10" fill="url(#highlightGrad)" stroke="#0ea5e9" stroke-width="1.2"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="600" fill="#7dd3fc">
-          ⚡ Fast wgpu inking
+          ✨ Windows &amp; Android Support
        </text>
      </g>
-      <!-- Pill 2: Stylus mit Druck -->
+      <!-- Pill 2: New Import Functions -->
-      <g transform="translate(164, 0)">
+      <g transform="translate(262, 0)">
-        <rect width="214" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="348" height="36" rx="10" fill="url(#highlightGrad)" stroke="#0ea5e9" stroke-width="1.2"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="600" fill="#7dd3fc">
-          🖊️ Pressure &amp; palm rejection
+          📥 Import: Xournal++, Rnote, Saber &amp; PDF
        </text>
      </g>
-      <!-- Pill 3: Formerkennung -->
+      <!-- Pill 3: Fast Inking -->
-      <g transform="translate(390, 0)">
+      <g transform="translate(622, 0)">
-        <rect width="216" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="160" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
-          📐 Shape recognition &amp; ruler
+          ⚡ Fast wgpu Inking
        </text>
      </g>
    </g>
    <!-- Feature Highlights: Row 2 (Core Strengths) -->
    <g transform="translate(0, 262)">
      <!-- Pill 4: Pressure & Palm Rejection with Vector Stylus Icon -->
      <g transform="translate(0, 0)">
        <rect width="248" height="34" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
        <svg x="14" y="9" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="#38bdf8" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
          <path d="M17 3a2.828 2.828 0 1 1 4 4L7.5 20.5 2 22l1.5-5.5L17 3z"/>
        </svg>
        <text x="36" y="22" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
          Pressure &amp; Palm Rejection
        </text>
      </g>
-      <!-- Pill 4: 100% lokal -->
+      <!-- Pill 5: Shape Recognition & Ruler -->
-      <g transform="translate(618, 0)">
+      <g transform="translate(260, 0)">
-        <rect width="188" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="254" height="34" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="22" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
-          🔒 100% local &amp; atomic
+          📐 Shape Recognition &amp; Ruler
        </text>
      </g>
      <!-- Pill 6: 100% Local & Atomic -->
      <g transform="translate(526, 0)">
        <rect width="256" height="34" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
        <text x="14" y="22" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
          🔒 100% Local, Atomic &amp; Private
        </text>
      </g>
    </g>
  </g>
-</svg>
+</svg>
@@ -19,6 +19,12 @@
      <stop offset="100%" stop-color="#38bdf8" stop-opacity="0"/>
    </radialGradient>
    <!-- Highlight Card Gradient -->
    <linearGradient id="highlightGrad" x1="0%" y1="0%" x2="100%" y2="100%">
      <stop offset="0%" stop-color="#132644"/>
      <stop offset="100%" stop-color="#0d1b32"/>
    </linearGradient>
    <!-- Icon Hintergrund-Verlauf -->
    <linearGradient id="bgGrad" x1="0%" y1="0%" x2="100%" y2="100%">
      <stop offset="0%" stop-color="#1e2638"/>
@@ -121,58 +127,98 @@
  <!-- ==================== RECHTER BEREICH: TYPOGRAFIE & BADGES ==================== -->
  <g transform="translate(360, 0)">
-    <!-- Version & Platform Pill -->
+    <!-- Top Badges -->
-    <g transform="translate(0, 68)">
+    <g transform="translate(0, 56)">
-      <rect width="254" height="30" rx="15" fill="#1e293b" stroke="#334155" stroke-width="1.2"/>
+      <!-- Platform Pill (ohne Versionsnummer) -->
-      <circle cx="16" cy="15" r="4" fill="#22c55e"/>
+      <rect width="248" height="28" rx="14" fill="#1e293b" stroke="#334155" stroke-width="1.2"/>
-      <text x="28" y="20" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="600" fill="#cbd5e1" letter-spacing="0.5">
+      <circle cx="15" cy="14" r="4" fill="#22c55e"/>
-        v0.14.0 • LINUX • RUST &amp; WGPU
+      <text x="27" y="18.5" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="12" font-weight="600" fill="#cbd5e1" letter-spacing="0.6">
        LINUX • WINDOWS • ANDROID
      </text>
      <!-- Engine Pill -->
      <g transform="translate(260, 0)">
        <rect width="138" height="28" rx="14" fill="#1e293b" stroke="#334155" stroke-width="1.2"/>
        <text x="13" y="18.5" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="11.5" font-weight="600" fill="#94a3b8" letter-spacing="0.5">
          ⚡ RUST &amp; WGPU
        </text>
      </g>
      <!-- Major Update Pill -->
      <g transform="translate(410, 0)">
        <rect width="164" height="28" rx="14" fill="url(#highlightGrad)" stroke="#0ea5e9" stroke-width="1.2"/>
        <circle cx="15" cy="14" r="3.5" fill="#38bdf8"/>
        <text x="27" y="18.5" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="11.5" font-weight="700" fill="#38bdf8" letter-spacing="0.5">
          GROSSES UPDATE
        </text>
      </g>
    </g>
    <!-- Haupttitel: ink-notes -->
-    <text x="0" y="162" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="800" font-size="64" letter-spacing="-1">
+    <text x="0" y="140" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="800" font-size="58" letter-spacing="-1">
      <tspan fill="url(#textInkGrad)">ink</tspan><tspan fill="#f8fafc">-notes</tspan>
    </text>
    <!-- Subtitle / Tagline -->
-    <text x="0" y="206" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="400" font-size="22" fill="#94a3b8">
+    <text x="0" y="178" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-weight="400" font-size="20" fill="#94a3b8">
      Notizbuch- &amp; PDF-Annotations-App für Stift, Touch und Maus
    </text>
-    <!-- Feature Pills / Highlights -->
+    <!-- Feature Highlights: Row 1 (Brandneue Hauptfeatures) -->
-    <g transform="translate(0, 248)">
+    <g transform="translate(0, 214)">
-      <!-- Pill 1: Niedrige Latenz -->
+      <!-- Pill 1: Windows & Android Support -->
      <g transform="translate(0, 0)">
-        <rect width="186" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="254" height="36" rx="10" fill="url(#highlightGrad)" stroke="#0ea5e9" stroke-width="1.2"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="600" fill="#7dd3fc">
-          ⚡ Schnelles wgpu-Inking
+          ✨ Windows- &amp; Android-Support
        </text>
      </g>
-      <!-- Pill 2: Stylus mit Druck -->
+      <!-- Pill 2: Neue Import-Funktionen -->
-      <g transform="translate(198, 0)">
+      <g transform="translate(266, 0)">
-        <rect width="190" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="348" height="36" rx="10" fill="url(#highlightGrad)" stroke="#0ea5e9" stroke-width="1.2"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="600" fill="#7dd3fc">
-          🖊️ Druck &amp; Palm Rejection
+          📥 Import: Xournal++, Rnote, Saber &amp; PDF
        </text>
      </g>
-      <!-- Pill 3: Formerkennung -->
+      <!-- Pill 3: Schnelles wgpu-Inking -->
-      <g transform="translate(400, 0)">
+      <g transform="translate(626, 0)">
-        <rect width="182" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="156" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
          ⚡ wgpu-Inking
        </text>
      </g>
    </g>
    <!-- Feature Highlights: Row 2 (Kernfunktionen) -->
    <g transform="translate(0, 262)">
      <!-- Pill 4: Stiftdruck & Palm Rejection with Vector Stylus Icon -->
      <g transform="translate(0, 0)">
        <rect width="248" height="34" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
        <svg x="14" y="9" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="#38bdf8" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
          <path d="M17 3a2.828 2.828 0 1 1 4 4L7.5 20.5 2 22l1.5-5.5L17 3z"/>
        </svg>
        <text x="36" y="22" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
          Druck &amp; Palm Rejection
        </text>
      </g>
      <!-- Pill 5: Formenerkennung & Lineal -->
      <g transform="translate(260, 0)">
        <rect width="254" height="34" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
        <text x="14" y="22" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
          📐 Formenerkennung &amp; Lineal
        </text>
      </g>
-      <!-- Pill 4: 100% lokal -->
+      <!-- Pill 6: 100% lokal, atomar & privat -->
-      <g transform="translate(594, 0)">
+      <g transform="translate(526, 0)">
-        <rect width="176" height="36" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
+        <rect width="256" height="34" rx="10" fill="#182236" stroke="#253554" stroke-width="1"/>
-        <text x="14" y="23" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13.5" font-weight="500" fill="#93c5fd">
+        <text x="14" y="22" font-family="-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu, sans-serif" font-size="13" font-weight="500" fill="#93c5fd">
-          🔒 100% lokal &amp; atomar
+          🔒 100% lokal, atomar &amp; privat
        </text>
      </g>
    </g>
  </g>
-</svg>
+</svg>
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- Manifest of the Android app (Issue #42). scripts/package-android.sh fills in the version.
-     NativeActivity loads libink_notes.so, whose android_main runs the app. -->
+     InkActivity (packaging/android/java) extends NativeActivity, which loads libink_notes.so;
     its android_main runs the app. -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="eu.pansi.inknotes"
    android:versionCode="@VERSION_CODE@"
@@ -11,13 +12,13 @@
    <application
        android:label="ink-notes"
        android:icon="@mipmap/ic_launcher"
-        android:hasCode="false"
+        android:hasCode="true"
        android:extractNativeLibs="true"
        android:theme="@android:style/Theme.Material.Light.NoActionBar">
        <!-- configChanges: rotating the tablet or attaching a keyboard must not restart the
             activity; the app adapts to the new window size itself -->
        <activity
-            android:name="android.app.NativeActivity"
+            android:name="eu.pansi.inknotes.InkActivity"
            android:exported="true"
            android:launchMode="singleTask"
            android:configChanges="orientation|screenSize|smallestScreenSize|screenLayout|keyboard|keyboardHidden|navigation|density|uiMode|fontScale|locale|layoutDirection">
@@ -0,0 +1,25 @@
 # Build environment for the Android APK (Issue #45): fixed versions of the JDK, Android SDK,
 # NDK and Rust, so that the APK can be built the same way anywhere.
 # Used by scripts/build-apk-container.sh (podman or docker).
 FROM docker.io/library/ubuntu:24.04
 ARG RUST_VERSION=1.99.0
 RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
        ca-certificates curl unzip zip openjdk-17-jdk-headless build-essential pkg-config \
    && rm -rf /var/lib/apt/lists/*
 ENV ANDROID_HOME=/opt/android-sdk \
    RUSTUP_HOME=/opt/rustup \
    CARGO_HOME=/opt/cargo \
    PATH=/opt/cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 COPY scripts/setup-android-sdk.sh /tmp/setup-android-sdk.sh
 RUN /tmp/setup-android-sdk.sh && rm /tmp/setup-android-sdk.sh
 RUN curl -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal \
        --default-toolchain "${RUST_VERSION}" --target aarch64-linux-android \
    && chmod -R a+rwX /opt/cargo /opt/rustup
 WORKDIR /src
@@ -0,0 +1,209 @@
 package eu.pansi.inknotes;
 import android.app.NativeActivity;
 import android.content.Context;
 import android.content.Intent;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
 import android.provider.OpenableColumns;
 import android.text.InputType;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.inputmethod.BaseInputConnection;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
 import android.view.inputmethod.InputMethodManager;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.InputStream;
 import java.io.OutputStream;
 /**
 * The app's activity (Issue #42): NativeActivity runs the Rust code (android_main in
 * libink_notes.so); this class adds what NativeActivity lacks.
 *
 * - Text input: NativeActivity's view offers keyboards no input connection, so they can only
 *   send key events, and characters without a key (umlauts chosen by long press, ...) got lost.
 *   An invisible view with its own input connection passes committed text to Rust.
 * - Picking files: the system file dialog (ACTION_OPEN_DOCUMENT); the chosen file is copied to
 *   the cache folder, as Rust can only open files by path.
 *
 * Rust calls showKeyboard and pickFile through JNI and receives the native* calls
 * (src/android_bridge.rs).
 */
 public class InkActivity extends NativeActivity {
    static {
        // NativeActivity loads the library too, but without System.loadLibrary the native
        // methods below would not be found
        System.loadLibrary("ink_notes");
    }
    private static final int PICK_FILE = 1;
    static native void nativeCommitText(String text);
    static native void nativeDeleteSurroundingText(int before, int after);
    /** Path of the copied file, or null if nothing was chosen or copying failed. */
    static native void nativeFilePicked(String path);
    private TextSink textSink;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        textSink = new TextSink(this);
        addContentView(textSink, new ViewGroup.LayoutParams(1, 1));
    }
    /** Shows or hides the soft keyboard; called from Rust on any thread. */
    public void showKeyboard(final boolean show) {
        runOnUiThread(() -> {
            InputMethodManager imm =
                    (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
            if (show) {
                textSink.requestFocus();
                imm.restartInput(textSink);
                imm.showSoftInput(textSink, 0);
            } else {
                imm.hideSoftInputFromWindow(textSink.getWindowToken(), 0);
                textSink.clearFocus();
            }
        });
    }
    /** Opens the system file dialog for files of this MIME type ("image/*", "*" + "/*"). */
    public void pickFile(final String mimeType) {
        runOnUiThread(() -> {
            Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
            intent.addCategory(Intent.CATEGORY_OPENABLE);
            intent.setType(mimeType);
            try {
                startActivityForResult(intent, PICK_FILE);
            } catch (Exception e) {
                nativeFilePicked(null);
            }
        });
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode != PICK_FILE) {
            return;
        }
        final Uri uri = (resultCode == RESULT_OK && data != null) ? data.getData() : null;
        if (uri == null) {
            nativeFilePicked(null);
            return;
        }
        // Copying a large file must not block the UI thread
        new Thread(() -> {
            String path = null;
            try {
                path = copyToCache(uri);
            } catch (Exception e) {
                android.util.Log.w("ink-notes", "copying the picked file failed", e);
            }
            nativeFilePicked(path);
        }).start();
    }
    private String copyToCache(Uri uri) throws Exception {
        String name = "import";
        try (Cursor cursor = getContentResolver().query(
                uri, new String[] {OpenableColumns.DISPLAY_NAME}, null, null, null)) {
            if (cursor != null && cursor.moveToFirst() && !cursor.isNull(0)) {
                name = cursor.getString(0).replace('/', '_');
            }
        }
        File dir = new File(getCacheDir(), "picked");
        File[] old = dir.listFiles();
        if (old != null) {
            for (File f : old) {
                f.delete();
            }
        }
        dir.mkdirs();
        File target = new File(dir, name);
        try (InputStream in = getContentResolver().openInputStream(uri);
                OutputStream out = new FileOutputStream(target)) {
            byte[] buffer = new byte[64 * 1024];
            int n;
            while ((n = in.read(buffer)) > 0) {
                out.write(buffer, 0, n);
            }
        }
        return target.getAbsolutePath();
    }
    /** Invisible view that receives the keyboard's text. */
    private static class TextSink extends View {
        TextSink(Context context) {
            super(context);
            setFocusable(true);
            setFocusableInTouchMode(true);
        }
        @Override
        public boolean onCheckIsTextEditor() {
            return true;
        }
        @Override
        public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
            // Visible password: keyboards commit every character right away instead of
            // composing words with suggestions, which the app could not show
            outAttrs.inputType = InputType.TYPE_CLASS_TEXT
                    | InputType.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD
                    | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS
                    | InputType.TYPE_TEXT_FLAG_MULTI_LINE;
            outAttrs.imeOptions = EditorInfo.IME_FLAG_NO_EXTRACT_UI
                    | EditorInfo.IME_FLAG_NO_FULLSCREEN
                    | EditorInfo.IME_ACTION_NONE;
            return new TextConnection(this);
        }
    }
    /** Passes committed text and deletions to Rust; key events go the usual way. */
    private static class TextConnection extends BaseInputConnection {
        private String composing = "";
        TextConnection(View view) {
            super(view, false);
        }
        @Override
        public boolean commitText(CharSequence text, int newCursorPosition) {
            composing = "";
            if (text.length() > 0) {
                nativeCommitText(text.toString());
            }
            return true;
        }
        @Override
        public boolean setComposingText(CharSequence text, int newCursorPosition) {
            // Not shown while composing; taken over once finished
            composing = text.toString();
            return true;
        }
        @Override
        public boolean finishComposingText() {
            if (!composing.isEmpty()) {
                nativeCommitText(composing);
                composing = "";
            }
            return true;
        }
        @Override
        public boolean deleteSurroundingText(int beforeLength, int afterLength) {
            nativeDeleteSurroundingText(beforeLength, afterLength);
            return true;
        }
    }
 }
@@ -84,6 +84,16 @@
  </branding>
  <content_rating type="oars-1.1" />
  <releases>
    <release version="0.41.0" date="2026-10-28">
      <description>
        <p>Experimental: computes handwritten formulas after an equals sign and offers the result next to it (turn on in the menu under input).</p>
      </description>
    </release>
    <release version="0.40.0" date="2026-10-28">
      <description>
        <p>New Android version: a signed APK for 64-bit ARM devices with pen, touch, soft keyboard, file import and exports to Downloads.</p>
      </description>
    </release>
    <release version="0.39.3" date="2026-10-27">
      <description>
        <p>Much lower battery use: the app no longer redraws the window continuously while nothing happens.</p>
@@ -84,6 +84,16 @@
  </branding>
  <content_rating type="oars-1.1" />
  <releases>
    <release version="0.41.0" date="2026-10-28">
      <description>
        <p>Experimental: computes handwritten formulas after an equals sign and offers the result next to it (turn on in the menu under input).</p>
      </description>
    </release>
    <release version="0.40.0" date="2026-10-28">
      <description>
        <p>New Android version: a signed APK for 64-bit ARM devices with pen, touch, soft keyboard, file import and exports to Downloads.</p>
      </description>
    </release>
    <release version="0.39.3" date="2026-10-27">
      <description>
        <p>Much lower battery use: the app no longer redraws the window continuously while nothing happens.</p>
@@ -3,6 +3,8 @@
 Notebook app for pen, touch and mouse on Linux (tested on Zorin OS 18 / Ubuntu 24.04).
 ### Highlights:
 - **Computing formulas (experimental)**: Turn on in ☰ → Input ("Compute formulas after “=”"). After a handwritten `=` and a short pause, the result appears next to it together with what was read, e.g. `2⁴ = 16` or `(x + 3)² = x² + 6x + 9`; tapping it with the pen or clicking inserts it as text in the ink color and as high as the handwriting. Digits, `+ − · : /`, parentheses, exponents, fraction bars, decimal commas and `x`, `y`, `a`, `b` are read; numbers are computed exactly, expressions with variables multiplied out. Recognition runs offline without machine learning – feedback with real handwriting welcome (Issue #46)
 - **Android**: `ink-notes_<version>_arm64.apk` brings ink-notes to Android 8 and newer (64-bit ARM) – download it on the device and open it to install. The pen is told apart from fingers (pressure, pen buttons, eraser end, palm rejection), text fields open the soft keyboard, import and inserting images use the system file dialog, and exports are saved to `Download/ink-notes` (Android 10 and newer). Notebooks live in the app's own storage and are removed when uninstalling; updates are installed by opening the new APK. Nothing changes on Linux and Windows
 - **Battery drain fixed**: ink-notes redrew its window at full frame rate even when nothing happened, which kept the app and the desktop (e.g. gnome-shell) busy and drained the battery. It now only draws when something changes; idle CPU load drops to practically zero. Also applies to Windows. Internally, the Android version now follows the app lifecycle and can be packed into an APK (not part of the release yet)
 - **PDF export on current lopdf**: The PDF export uses its own small PDF writer on top of lopdf 0.46 instead of the outdated printpdf 0.7 (which pinned lopdf 0.31). Exported PDFs look the same – layers, searchable text, images, highlighters and bookmarks stay as before
 - **Windows mouse fix**: The mouse works normally again in the Windows version – Windows Ink reported it as a pen, so clicks and moves went the wrong way. Nothing changes on Linux
@@ -0,0 +1,48 @@
 #!/usr/bin/env bash
 # ==============================================================================
 # Builds the APK inside the container from packaging/android/Containerfile (Issue #45),
 # with podman (preferred) or docker. Needs nothing else on the host.
 # Result: target/ink-notes_<version>_arm64.apk
 #
 # Signing key as in scripts/package-android.sh: ANDROID_KEYSTORE (path on the host),
 # ANDROID_KEYSTORE_PASS, ANDROID_KEY_ALIAS; otherwise a debug key (kept below
 # target/android-container/home, so that test builds can update each other).
 # ==============================================================================
 set -euo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 ROOT_DIR="$(cd "${SCRIPT_DIR}/.." && pwd)"
 cd "${ROOT_DIR}"
 if command -v podman >/dev/null 2>&1; then
    ENGINE=podman
    USER_ARGS=(--userns=keep-id)
 elif command -v docker >/dev/null 2>&1; then
    ENGINE=docker
    USER_ARGS=(--user "$(id -u):$(id -g)")
 else
    echo "FEHLER: weder podman noch docker gefunden."
    exit 1
 fi
 IMAGE="ink-notes-android"
 echo "=== Baue Container-Image ${IMAGE} ==="
 "${ENGINE}" build -t "${IMAGE}" -f packaging/android/Containerfile .
 mkdir -p target/android-container/home
 ARGS=(
    --rm "${USER_ARGS[@]}"
    -v "${ROOT_DIR}:/src"
    -e HOME=/src/target/android-container/home
    -e CARGO_TARGET_DIR=/src/target/android-container
    # Downloaded crates stay between runs
    -e CARGO_HOME=/src/target/android-container/cargo
 )
 if [ -n "${ANDROID_KEYSTORE:-}" ]; then
    ARGS+=(
        -v "$(realpath "${ANDROID_KEYSTORE}"):/keystore:ro"
        -e ANDROID_KEYSTORE=/keystore
        -e ANDROID_KEYSTORE_PASS -e ANDROID_KEY_ALIAS
    )
 fi
 "${ENGINE}" run "${ARGS[@]}" "${IMAGE}" scripts/package-android.sh
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 # ==============================================================================
 # Haupt-Release-Build-Skript für ink-notes (Zorin OS 18 / Linux)
-# Erstellt .deb, .AppImage, Windows-.exe, SHA256-Prüfsummen und deren Minisign-Signatur in target/
+# Erstellt .deb, .AppImage, Windows-.exe, (mit vorhandener APK) SHA256-Prüfsummen und deren Minisign-Signatur in target/
 # ==============================================================================
 set -euo pipefail
@@ -14,6 +14,8 @@ VERSION=$(grep -m1 '^version = ' Cargo.toml | cut -d '"' -f2)
 DEB_NAME="ink-notes_${VERSION}_amd64.deb"
 APPIMAGE_NAME="ink-notes_${VERSION}_x86_64.AppImage"
 EXE_NAME="ink-notes_${VERSION}_x86_64.exe"
 # Built separately (scripts/package-android.sh, CI job android); listed in the checksums if present
 APK_NAME="ink-notes_${VERSION}_arm64.apk"
 CHECKSUM_FILE="SHA256SUMS.txt"
 echo "======================================================================"
@@ -32,7 +34,14 @@ echo "======================================================================"
 # 4. Checksums berechnen
 echo "=== Berechne SHA256-Prüfsummen in target/${CHECKSUM_FILE} ==="
 cd "${ROOT_DIR}/target"
-sha256sum "${DEB_NAME}" "${APPIMAGE_NAME}" "${EXE_NAME}" > "${CHECKSUM_FILE}"
+RELEASE_FILES=("${DEB_NAME}" "${APPIMAGE_NAME}" "${EXE_NAME}")
 if [ -f "${APK_NAME}" ]; then
    RELEASE_FILES+=("${APK_NAME}")
 elif [ "${INK_NOTES_REQUIRE_APK:-0}" = "1" ]; then
    echo "FEHLER: target/${APK_NAME} fehlt (INK_NOTES_REQUIRE_APK=1)."
    exit 1
 fi
 sha256sum "${RELEASE_FILES[@]}" > "${CHECKSUM_FILE}"
 # 5. Prüfsummen signieren (Pflicht für In-App-Updates)
 # Signiert wird mit rsign2 (minisign-kompatibles Format): Der Schlüssel wurde mit
@@ -77,7 +86,7 @@ fi
 echo "======================================================================"
 echo "Release-Artefakte für v${VERSION} erfolgreich erstellt:"
 echo "======================================================================"
-ls -lh "${DEB_NAME}" "${APPIMAGE_NAME}" "${EXE_NAME}" "${CHECKSUM_FILE}"
+ls -lh "${RELEASE_FILES[@]}" "${CHECKSUM_FILE}"
 if [ -f "${SIGNATURE_FILE}" ]; then ls -lh "${SIGNATURE_FILE}"; fi
 echo ""
 echo "Inhalt von target/${CHECKSUM_FILE}:"
@@ -1,8 +1,9 @@
 #!/usr/bin/env bash
 # ==============================================================================
 # Builds the Android app target/ink-notes_<version>_arm64.apk (Issues #42, #45)
-# without Gradle: the Rust library is built as cdylib with the NDK, aapt2 links the
+# without Gradle: the Rust library is built as cdylib with the NDK, javac and d8 compile the
-# manifest and the icon, zipalign and apksigner finish the APK.
+# activity (packaging/android/java), aapt2 links the manifest and the icon, zipalign and
 # apksigner finish the APK. Needs a JDK (javac, keytool).
 #
 # Needs the Android SDK (build-tools, platform android-34) and the NDK:
 #   ANDROID_HOME      SDK folder (default: ~/android-sdk)
@@ -35,12 +36,16 @@ BUILD_TOOLS=$(ls -d "${ANDROID_HOME}"/build-tools/*/ 2>/dev/null | sort -V | tai
 ANDROID_JAR="${ANDROID_HOME}/platforms/android-${TARGET_SDK}/android.jar"
 NDK_BIN="${ANDROID_NDK_HOME%/}/toolchains/llvm/prebuilt/linux-x86_64/bin"
-for needed in "${NDK_BIN}/${TARGET}${MIN_SDK}-clang" "${BUILD_TOOLS}aapt2" "${ANDROID_JAR}"; do
+for needed in "${NDK_BIN}/${TARGET}${MIN_SDK}-clang" "${BUILD_TOOLS}aapt2" "${BUILD_TOOLS}d8" "${ANDROID_JAR}"; do
    if [ ! -e "${needed}" ]; then
        echo "FEHLER: ${needed} nicht gefunden (Android-SDK/NDK, siehe Kopf des Skripts)."
        exit 1
    fi
 done
 if ! command -v javac >/dev/null 2>&1; then
    echo "FEHLER: javac nicht gefunden (JDK 17 oder neuer)."
    exit 1
 fi
 if command -v rustup >/dev/null 2>&1; then
    rustup target add "${TARGET}"
 fi
@@ -55,7 +60,7 @@ LIB="${CARGO_TARGET_DIR:-target}/${TARGET}/release/libink_notes.so"
 echo "=== [2/4] Ressourcen und Manifest ==="
 WORK="target/android-apk"
 rm -rf "${WORK}"
-mkdir -p "${WORK}/res/mipmap-xxxhdpi" "${WORK}/compiled" "${WORK}/apk/lib/${ABI}"
+mkdir -p "${WORK}/res/mipmap-xxxhdpi" "${WORK}/compiled" "${WORK}/apk/lib/${ABI}" "${WORK}/classes"
 cp assets/ink-notes.png "${WORK}/res/mipmap-xxxhdpi/ic_launcher.png"
 sed -e "s/@VERSION_CODE@/${VERSION_CODE}/" -e "s/@VERSION@/${VERSION}/" \
    packaging/android/AndroidManifest.xml >"${WORK}/AndroidManifest.xml"
@@ -65,9 +70,13 @@ sed -e "s/@VERSION_CODE@/${VERSION_CODE}/" -e "s/@VERSION@/${VERSION}/" \
    --min-sdk-version "${MIN_SDK}" --target-sdk-version "${TARGET_SDK}" \
    "${WORK}/compiled/res.zip"
-echo "=== [3/4] Native Bibliothek hinzufügen ==="
+echo "=== [3/4] Activity und native Bibliothek hinzufügen ==="
 javac -source 8 -target 8 -nowarn -Xlint:-options -classpath "${ANDROID_JAR}" \
    -d "${WORK}/classes" $(find packaging/android/java -name '*.java')
 "${BUILD_TOOLS}d8" --min-api "${MIN_SDK}" --lib "${ANDROID_JAR}" --output "${WORK}/apk" \
    $(find "${WORK}/classes" -name '*.class')
 cp "${LIB}" "${WORK}/apk/lib/${ABI}/"
-(cd "${WORK}/apk" && zip -q -r ../unaligned.apk lib)
+(cd "${WORK}/apk" && zip -q -r ../unaligned.apk classes.dex lib)
 "${BUILD_TOOLS}zipalign" -f -p 4 "${WORK}/unaligned.apk" "${WORK}/aligned.apk"
 echo "=== [4/4] Signieren ==="
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 # ==============================================================================
 # Veröffentlicht ein Release auf dem Gitea-Server (gitea.pansi.eu)
-# Lädt .deb, .AppImage, .exe, SHA256SUMS.txt und SHA256SUMS.txt.minisig idempotent als Release-Assets hoch.
+# Lädt .deb, .AppImage, .exe, .apk (falls gebaut), SHA256SUMS.txt und SHA256SUMS.txt.minisig idempotent als Release-Assets hoch.
 # ==============================================================================
 set -euo pipefail
@@ -33,6 +33,7 @@ RELEASE_TITLE="ink-notes ${TAG_NAME}"
 DEB_FILE="${ROOT_DIR}/target/ink-notes_${VERSION}_amd64.deb"
 APPIMAGE_FILE="${ROOT_DIR}/target/ink-notes_${VERSION}_x86_64.AppImage"
 EXE_FILE="${ROOT_DIR}/target/ink-notes_${VERSION}_x86_64.exe"
 APK_FILE="${ROOT_DIR}/target/ink-notes_${VERSION}_arm64.apk"
 CHECKSUMS_FILE="${ROOT_DIR}/target/SHA256SUMS.txt"
 SIGNATURE_FILE="${CHECKSUMS_FILE}.minisig"
 TEMPLATE_FILE="${ROOT_DIR}/packaging/release-notes.md.tmpl"
@@ -238,6 +239,9 @@ except Exception:
 upload_asset "${DEB_FILE}"
 upload_asset "${APPIMAGE_FILE}"
 upload_asset "${EXE_FILE}"
 if [ -f "${APK_FILE}" ]; then
    upload_asset "${APK_FILE}"
 fi
 upload_asset "${CHECKSUMS_FILE}"
 upload_asset "${SIGNATURE_FILE}"
@@ -0,0 +1,40 @@
 #!/usr/bin/env bash
 # ==============================================================================
 # Installs the Android SDK parts that scripts/package-android.sh needs, in fixed versions
 # (Issue #45): command-line tools, platform 34, build-tools 34.0.0 and NDK 28.2.
 # Used by the CI and packaging/android/Containerfile; works for a local SDK as well.
 #
 #   ANDROID_HOME  target folder (default: ~/android-sdk)
 #
 # Needs curl, unzip and a JDK 17 or newer (sdkmanager is a Java program).
 # ==============================================================================
 set -euo pipefail
 ANDROID_HOME="${ANDROID_HOME:-${HOME}/android-sdk}"
 CMDLINE_TOOLS_ZIP="commandlinetools-linux-11076708_latest.zip"
 CMDLINE_TOOLS_SHA256="2d2d50857e4eb553af5a6dc3ad507a17adf43d115264b1afc116f95c92e5e258"
 PACKAGES=(
    "platforms;android-34"
    "build-tools;34.0.0"
    "ndk;28.2.13676358"
 )
 SDKMANAGER="${ANDROID_HOME}/cmdline-tools/latest/bin/sdkmanager"
 if [ ! -x "${SDKMANAGER}" ]; then
    echo "=== Lade Android Command-line Tools ==="
    TMP="$(mktemp -d)"
    trap 'rm -rf "${TMP}"' EXIT
    curl -sSfL -o "${TMP}/${CMDLINE_TOOLS_ZIP}" \
        "https://dl.google.com/android/repository/${CMDLINE_TOOLS_ZIP}"
    echo "${CMDLINE_TOOLS_SHA256}  ${TMP}/${CMDLINE_TOOLS_ZIP}" | sha256sum -c -
    unzip -q "${TMP}/${CMDLINE_TOOLS_ZIP}" -d "${TMP}"
    mkdir -p "${ANDROID_HOME}/cmdline-tools"
    rm -rf "${ANDROID_HOME}/cmdline-tools/latest"
    mv "${TMP}/cmdline-tools" "${ANDROID_HOME}/cmdline-tools/latest"
 fi
 echo "=== Installiere ${PACKAGES[*]} nach ${ANDROID_HOME} ==="
 # sdkmanager ends with an error when `yes` is cut off by a closed pipe; that's fine
 (yes || true) | "${SDKMANAGER}" --sdk_root="${ANDROID_HOME}" --licenses >/dev/null
 "${SDKMANAGER}" --sdk_root="${ANDROID_HOME}" --install "${PACKAGES[@]}" >/dev/null
 echo "Android-SDK bereit: ${ANDROID_HOME}"
@@ -0,0 +1,178 @@
 //! Android: calls into the app's Java activity and what it reports back (Issue #42).
 //!
 //! `packaging/android/java/eu/pansi/inknotes/InkActivity.java` extends NativeActivity with
 //! text input through an input connection (so that keyboards can send any character) and the
 //! system file dialog. Rust calls its methods through JNI; it calls the `native*` functions
 //! below, possibly on another thread, so they only queue messages and wake the event loop.
 use std::path::PathBuf;
 use std::sync::Mutex;
 use jni::objects::{JObject, JString, JValue};
 use jni::sys::jint;
 use jni::JNIEnv;
 use crate::file_picker::PickerKind;
 use crate::ui::UiAction;
 enum Message {
    Text(String),
    Delete { before: u32, after: u32 },
    Picked(Option<PathBuf>),
 }
 static MESSAGES: Mutex<Vec<Message>> = Mutex::new(Vec::new());
 /// What the open file dialog is for
 static PICKING: Mutex<Option<PickerKind>> = Mutex::new(None);
 fn push(message: Message) {
    MESSAGES
        .lock()
        .unwrap_or_else(|e| e.into_inner())
        .push(message);
    if let Some(app) = crate::platform::android_app() {
        app.create_waker().wake();
    }
 }
 #[no_mangle]
 pub extern "system" fn Java_eu_pansi_inknotes_InkActivity_nativeCommitText(
    mut env: JNIEnv,
    _class: JObject,
    text: JString,
 ) {
    if let Ok(text) = env.get_string(&text) {
        push(Message::Text(text.into()));
    }
 }
 #[no_mangle]
 pub extern "system" fn Java_eu_pansi_inknotes_InkActivity_nativeDeleteSurroundingText(
    _env: JNIEnv,
    _class: JObject,
    before: jint,
    after: jint,
 ) {
    push(Message::Delete {
        before: before.max(0) as u32,
        after: after.max(0) as u32,
    });
 }
 #[no_mangle]
 pub extern "system" fn Java_eu_pansi_inknotes_InkActivity_nativeFilePicked(
    mut env: JNIEnv,
    _class: JObject,
    path: JString,
 ) {
    let path = if path.is_null() {
        None
    } else {
        env.get_string(&path)
            .ok()
            .map(|p| PathBuf::from(String::from(p)))
    };
    push(Message::Picked(path));
 }
 /// Is a message waiting (then the app draws a new frame to take it)?
 pub fn has_messages() -> bool {
    !MESSAGES
        .lock()
        .unwrap_or_else(|e| e.into_inner())
        .is_empty()
 }
 /// Typed text and deletions as egui input, and the action for a picked file.
 pub fn take_messages() -> (Vec<egui::Event>, Vec<UiAction>) {
    let messages = std::mem::take(&mut *MESSAGES.lock().unwrap_or_else(|e| e.into_inner()));
    let mut events = Vec::new();
    let mut actions = Vec::new();
    for message in messages {
        match message {
            Message::Text(text) => events.extend(crate::osk::committed_text_events(&text)),
            Message::Delete { before, after } => {
                events.extend(crate::osk::deletion_key_events(before, after))
            }
            Message::Picked(path) => {
                let kind = PICKING.lock().unwrap_or_else(|e| e.into_inner()).take();
                match (kind, path) {
                    (Some(PickerKind::Image), Some(path)) => {
                        actions.push(UiAction::InsertImageFile(path))
                    }
                    (Some(PickerKind::Import), Some(path)) => {
                        actions.push(UiAction::ImportFile(path))
                    }
                    _ => {}
                }
            }
        }
    }
    (events, actions)
 }
 /// Runs `f` with the JNI environment and the activity; local references it creates are
 /// freed afterwards.
 fn with_activity(
    f: impl FnOnce(&mut JNIEnv, &JObject) -> jni::errors::Result<()>,
 ) -> Result<(), String> {
    let app = crate::platform::android_app().ok_or("no activity")?;
    // Safety: pointers to the VM and the activity (a global reference) that live as long as
    // the app
    let vm = unsafe { jni::JavaVM::from_raw(app.vm_as_ptr().cast()) }.map_err(|e| e.to_string())?;
    let mut env = vm
        .attach_current_thread_permanently()
        .map_err(|e| e.to_string())?;
    let activity = unsafe { JObject::from_raw(app.activity_as_ptr().cast()) };
    let result = env.with_local_frame(16, |env| f(env, &activity));
    if env.exception_check().unwrap_or(false) {
        let _ = env.exception_describe();
        let _ = env.exception_clear();
    }
    result.map_err(|e| e.to_string())
 }
 pub fn show_keyboard(show: bool) {
    let result = with_activity(|env, activity| {
        env.call_method(
            activity,
            "showKeyboard",
            "(Z)V",
            &[JValue::Bool(show.into())],
        )
        .map(|_| ())
    });
    if let Err(err) = result {
        log::warn!("showKeyboard: {err}");
    }
 }
 /// Opens the system file dialog instead of the app's own; false if that is not possible
 /// (e.g. for choosing a folder).
 pub fn pick_file(kind: PickerKind) -> bool {
    let mime_type = match kind {
        PickerKind::Image => "image/*",
        // Xournal++, Rnote and Saber files have no MIME type of their own
        PickerKind::Import => "*/*",
        PickerKind::Folder => return false,
    };
    *PICKING.lock().unwrap_or_else(|e| e.into_inner()) = Some(kind);
    let result = with_activity(|env, activity| {
        let mime = env.new_string(mime_type)?;
        env.call_method(
            activity,
            "pickFile",
            "(Ljava/lang/String;)V",
            &[JValue::Object(&mime)],
        )
        .map(|_| ())
    });
    match result {
        Ok(()) => true,
        Err(err) => {
            log::warn!("pickFile: {err}");
            *PICKING.lock().unwrap_or_else(|e| e.into_inner()) = None;
            false
        }
    }
 }
@@ -51,6 +51,13 @@ pub fn sanitize_filename_component(title: &str) -> String {
 /// `~/.config/user-dirs.dirs` (z. B. „Dokumente“), sonst `~/Documents`. Im Flatpak ist nur
 /// dieser Ordner beschreibbar, der Fallback allein träfe bei deutschen Systemen daneben.
 pub fn default_documents_dir() -> PathBuf {
    // Android: written into the app's own folder first, then copied to Downloads
    // (`platform::publish_export`)
    #[cfg(target_os = "android")]
    if let Some(dir) = crate::platform::android_app().and_then(|app| app.external_data_path()) {
        return dir.join("Documents");
    }
    if let Ok(dir) = std::env::var("XDG_DOCUMENTS_DIR") {
        if !dir.trim().is_empty() {
            return PathBuf::from(dir);
@@ -107,6 +107,7 @@ pub const EN: &[(&str, &str)] = &[
    ("Fehler beim Öffnen: {err}", "Error while opening: {err}"),
    ("Fehler: {err}", "Error: {err}"),
    ("Fehlermeldung: {message}", "Error message: {message}"),
    ("Formeln nach „=“ ausrechnen", "Compute formulas after “=”"),
    ("Formen (Shape)", "Shapes"),
    ("Formen: Striche werden zu Linien, Rechtecken, Kreisen … (S/F)", "Shapes: strokes become lines, rectangles, circles … (S/F)"),
    ("Fünfeck (Pentagon)", "Pentagon"),
@@ -186,6 +187,7 @@ pub const EN: &[(&str, &str)] = &[
    ("Mindestdruck", "Minimum pressure"),
    ("Mit dem Finger zeichnen", "Draw with finger"),
    ("Mittel", "Medium"),
    ("Nach einem handgeschriebenen „=“ erscheint das Ergebnis daneben, z. B. 2⁴ = 16. Antippen mit dem Stift oder Klicken fügt es als Text ein.\nGelesen werden Ziffern, + − · : /, Klammern, Hochzahlen, Brüche und x, y, a, b.", "After a handwritten “=” the result appears next to it, e.g. 2⁴ = 16. Tapping it with the pen or clicking inserts it as text.\nDigits, + − · : /, parentheses, exponents, fractions and x, y, a, b are read."),
    ("Name …", "Name …"),
    ("Neon-Gelb", "Neon yellow"),
    ("Netzwerk-Transportfehler: {t}", "Network transport error: {t}"),
@@ -1,5 +1,7 @@
 //! ink-notes: Latenzoptimierte Inking-App für Linux.
 #[cfg(target_os = "android")]
 pub mod android_bridge;
 pub mod app;
 pub mod assets;
 pub mod autosave;
@@ -16,12 +18,16 @@ pub mod i18n;
 pub mod image_layer;
 pub mod import;
 pub mod library;
 pub mod math;
 pub mod math_assist;
 pub mod math_ink;
 pub mod osk;
 pub mod page_export;
 pub mod paths;
 pub mod pdf_doc;
 pub mod pdf_merge;
 pub mod pdf_writer;
 pub mod pen;
 pub mod platform;
 pub mod rnote;
 pub mod ruler;
@@ -51,6 +57,7 @@ fn android_main(app: winit::platform::android::activity::AndroidApp) {
    );
    // Panics would otherwise only go to stderr, which Android discards
    std::panic::set_hook(Box::new(|info| log::error!("{info}")));
    platform::set_android_app(app.clone());
    if let Some(dir) = app.internal_data_path() {
        paths::set_app_dir(dir);
    }
@@ -0,0 +1,757 @@
 //! Exact evaluation of handwritten math (Issue #46, stage 1).
 //!
 //! Takes the text of a recognised expression such as `2^4`, `2,5 · 3` or `(x + 3)²`
 //! (optionally ending with `=`) and returns its result as text: `16`, `7,5` and
 //! `x² + 6x + 9`. Numbers are exact fractions, so `1 : 3 · 3` gives `1`, and expressions
 //! with variables are expanded into polynomials.
 //!
 //! The input is lenient towards how math is written by hand: decimal comma or point,
 //! `·`, `×`, `*` and `:`, `÷`, `/`, superscript exponents, Unicode minus signs and implicit
 //! multiplication (`2x`, `3(x + 1)`, `(a + b)(a − b)`).
 use std::cmp::Ordering;
 use std::collections::BTreeMap;
 use std::fmt::Write as _;
 /// Largest exponent for a polynomial that is not a plain number
 const MAX_POLYNOMIAL_EXPONENT: u32 = 32;
 /// Largest exponent for a plain number
 const MAX_NUMBER_EXPONENT: u32 = 1000;
 /// Results with more terms are not shown (they would not fit next to the `=` anyway)
 const MAX_TERMS: usize = 64;
 /// Terminating decimals with more digits after the separator are shown as fractions
 const MAX_DECIMALS: u32 = 12;
 /// Computes the result of `expression`, written for display after its `=` sign.
 ///
 /// `decimal_comma` selects the decimal separator of the result. Returns `None` if the
 /// expression cannot be read or computed (e.g. division by zero, a variable in a
 /// denominator or overflow), and also if there is nothing to compute, i.e. the result would
 /// just repeat the input (`5`, `x`, `2x`).
 pub fn solve(expression: &str, decimal_comma: bool) -> Option<String> {
    let tokens = tokenize(expression)?;
    let ast = Parser::new(&tokens).parse()?;
    if matches!(ast, Expr::Number(_) | Expr::Variable(_)) {
        return None;
    }
    let result = ast.eval()?;
    if result.terms.len() > MAX_TERMS {
        return None;
    }
    let text = result.format(decimal_comma);
    let compact = |s: &str| -> String {
        s.chars()
            .filter(|c| !c.is_whitespace())
            .map(|c| if c == '−' { '-' } else { c })
            .collect()
    };
    if compact(&text) == compact(expression.trim().trim_end_matches('=')) {
        return None;
    }
    Some(text)
 }
 /// `expression` written neatly for showing it, e.g. `2⁴` for `2^(4)`, `(x + 1)/2` for
 /// `((x+1)/(2))` or `2,5 · 3` for `2,5*3`. `None` if it cannot be read.
 pub fn display(expression: &str, decimal_comma: bool) -> Option<String> {
    let tokens = tokenize(expression)?;
    let ast = Parser::new(&tokens).parse()?;
    Some(ast.display(decimal_comma))
 }
 // --- Rational numbers ---------------------------------------------------------------------
 /// Exact fraction `num / den` with `den > 0`, always reduced
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 struct Rational {
    num: i128,
    den: i128,
 }
 fn gcd(mut a: i128, mut b: i128) -> i128 {
    a = a.abs();
    b = b.abs();
    while b != 0 {
        (a, b) = (b, a % b);
    }
    a
 }
 impl Rational {
    const ZERO: Rational = Rational { num: 0, den: 1 };
    const ONE: Rational = Rational { num: 1, den: 1 };
    fn new(num: i128, den: i128) -> Option<Rational> {
        // i128::MIN has no positive counterpart, which `gcd` and `neg` need
        if den == 0 || num == i128::MIN || den == i128::MIN {
            return None;
        }
        let g = gcd(num, den).max(1);
        let (mut num, mut den) = (num / g, den / g);
        if den < 0 {
            num = num.checked_neg()?;
            den = den.checked_neg()?;
        }
        Some(Rational { num, den })
    }
    fn integer(n: i128) -> Rational {
        Rational { num: n, den: 1 }
    }
    fn is_zero(self) -> bool {
        self.num == 0
    }
    fn add(self, other: Rational) -> Option<Rational> {
        let g = gcd(self.den, other.den);
        let den = (self.den / g).checked_mul(other.den)?;
        let num = self
            .num
            .checked_mul(other.den / g)?
            .checked_add(other.num.checked_mul(self.den / g)?)?;
        Rational::new(num, den)
    }
    fn neg(self) -> Option<Rational> {
        Some(Rational {
            num: self.num.checked_neg()?,
            den: self.den,
        })
    }
    fn mul(self, other: Rational) -> Option<Rational> {
        // Cross-reducing first keeps the intermediate products small
        let g1 = gcd(self.num, other.den).max(1);
        let g2 = gcd(other.num, self.den).max(1);
        let num = (self.num / g1).checked_mul(other.num / g2)?;
        let den = (self.den / g2).checked_mul(other.den / g1)?;
        Rational::new(num, den)
    }
    fn recip(self) -> Option<Rational> {
        Rational::new(self.den, self.num)
    }
    fn pow(self, exponent: i128) -> Option<Rational> {
        if exponent.unsigned_abs() > MAX_NUMBER_EXPONENT as u128 {
            return None;
        }
        let base = if exponent < 0 { self.recip()? } else { self };
        let mut result = Rational::ONE;
        for _ in 0..exponent.unsigned_abs() {
            result = result.mul(base)?;
        }
        Some(result)
    }
    fn as_integer(self) -> Option<i128> {
        (self.den == 1).then_some(self.num)
    }
    /// The number without its sign: as a terminating decimal if it has one with at most
    /// [`MAX_DECIMALS`] digits, otherwise as a fraction `p/q`.
    fn format_abs(self, decimal_comma: bool) -> String {
        let num = self.num.unsigned_abs();
        let den = self.den.unsigned_abs();
        let whole = num / den;
        let mut rest = num % den;
        if rest == 0 {
            return whole.to_string();
        }
        let mut reduced = den;
        let mut decimals = 0;
        for factor in [2, 5] {
            while reduced.is_multiple_of(factor) {
                reduced /= factor;
            }
        }
        if reduced == 1 {
            let mut digits = String::new();
            while rest != 0 && decimals <= MAX_DECIMALS {
                let Some(shifted) = rest.checked_mul(10) else {
                    break;
                };
                rest = shifted;
                digits.push(char::from(b'0' + (rest / den) as u8));
                rest %= den;
                decimals += 1;
            }
            if rest == 0 {
                let separator = if decimal_comma { ',' } else { '.' };
                return format!("{whole}{separator}{digits}");
            }
        }
        format!("{num}/{den}")
    }
 }
 // --- Polynomials --------------------------------------------------------------------------
 /// Product of variables with their exponents, e.g. `a²b` = `{a: 2, b: 1}`
 type Monomial = BTreeMap<char, u32>;
 /// Sum of monomials with exact coefficients; a plain number is the empty monomial
 #[derive(Debug, Clone, PartialEq, Eq)]
 struct Polynomial {
    terms: BTreeMap<Monomial, Rational>,
 }
 impl Polynomial {
    fn constant(value: Rational) -> Polynomial {
        let mut terms = BTreeMap::new();
        if !value.is_zero() {
            terms.insert(Monomial::new(), value);
        }
        Polynomial { terms }
    }
    fn variable(name: char) -> Polynomial {
        let mut terms = BTreeMap::new();
        terms.insert(Monomial::from([(name, 1)]), Rational::ONE);
        Polynomial { terms }
    }
    /// The value if this is a plain number
    fn as_constant(&self) -> Option<Rational> {
        match self.terms.len() {
            0 => Some(Rational::ZERO),
            1 => self.terms.get(&Monomial::new()).copied(),
            _ => None,
        }
    }
    fn add_term(&mut self, monomial: Monomial, coefficient: Rational) -> Option<()> {
        let sum = match self.terms.get(&monomial) {
            Some(existing) => existing.add(coefficient)?,
            None => coefficient,
        };
        if sum.is_zero() {
            self.terms.remove(&monomial);
        } else {
            self.terms.insert(monomial, sum);
        }
        Some(())
    }
    fn add(mut self, other: &Polynomial) -> Option<Polynomial> {
        for (monomial, coefficient) in &other.terms {
            self.add_term(monomial.clone(), *coefficient)?;
        }
        Some(self)
    }
    fn neg(&self) -> Option<Polynomial> {
        let mut terms = BTreeMap::new();
        for (monomial, coefficient) in &self.terms {
            terms.insert(monomial.clone(), coefficient.neg()?);
        }
        Some(Polynomial { terms })
    }
    fn mul(&self, other: &Polynomial) -> Option<Polynomial> {
        let mut product = Polynomial::constant(Rational::ZERO);
        for (m1, c1) in &self.terms {
            for (m2, c2) in &other.terms {
                let mut monomial = m1.clone();
                for (&name, &exponent) in m2 {
                    let e = monomial.entry(name).or_insert(0);
                    *e = e.checked_add(exponent)?;
                }
                product.add_term(monomial, c1.mul(*c2)?)?;
            }
            if product.terms.len() > MAX_TERMS * 4 {
                return None;
            }
        }
        Some(product)
    }
    fn div(&self, divisor: &Polynomial) -> Option<Polynomial> {
        let factor = divisor.as_constant()?.recip()?;
        self.mul(&Polynomial::constant(factor))
    }
    fn pow(&self, exponent: &Polynomial) -> Option<Polynomial> {
        let exponent = exponent.as_constant()?.as_integer()?;
        if let Some(base) = self.as_constant() {
            return Some(Polynomial::constant(base.pow(exponent)?));
        }
        if !(0..=MAX_POLYNOMIAL_EXPONENT as i128).contains(&exponent) {
            return None;
        }
        let mut result = Polynomial::constant(Rational::ONE);
        for _ in 0..exponent {
            result = result.mul(self)?;
        }
        Some(result)
    }
    /// E.g. `x² + 6x + 9`, `a² − b²`, `7,5`: highest degree first, then in alphabetical
    /// order of the variables (`a² + 2ab + b²`).
    fn format(&self, decimal_comma: bool) -> String {
        if self.terms.is_empty() {
            return "0".to_owned();
        }
        let degree = |m: &Monomial| m.values().sum::<u32>();
        let mut terms: Vec<_> = self.terms.iter().collect();
        terms.sort_by(|(a, _), (b, _)| degree(b).cmp(&degree(a)).then_with(|| graded_order(a, b)));
        let mut out = String::new();
        for (index, (monomial, coefficient)) in terms.into_iter().enumerate() {
            let negative = coefficient.num < 0;
            match (index, negative) {
                (0, true) => out.push('−'),
                (0, false) => {}
                (_, true) => out.push_str(" − "),
                (_, false) => out.push_str(" + "),
            }
            let magnitude = coefficient.format_abs(decimal_comma);
            if monomial.is_empty() {
                out.push_str(&magnitude);
                continue;
            }
            if magnitude.contains('/') {
                let _ = write!(out, "({magnitude})");
            } else if magnitude != "1" {
                out.push_str(&magnitude);
            }
            for (&name, &exponent) in monomial {
                out.push(name);
                if exponent > 1 {
                    out.push_str(&superscript(exponent));
                }
            }
        }
        out
    }
 }
 /// Order within the same degree: the monomial with the higher power of the alphabetically
 /// first variable comes first (`a²`, `ab`, `b²`).
 fn graded_order(a: &Monomial, b: &Monomial) -> Ordering {
    let names: std::collections::BTreeSet<char> = a.keys().chain(b.keys()).copied().collect();
    for name in names {
        let ea = a.get(&name).copied().unwrap_or(0);
        let eb = b.get(&name).copied().unwrap_or(0);
        match eb.cmp(&ea) {
            Ordering::Equal => continue,
            other => return other,
        }
    }
    Ordering::Equal
 }
 const SUPERSCRIPT_DIGITS: [char; 10] = ['⁰', '¹', '²', '³', '⁴', '⁵', '⁶', '⁷', '⁸', '⁹'];
 fn superscript(n: u32) -> String {
    n.to_string()
        .chars()
        .map(|d| SUPERSCRIPT_DIGITS[d.to_digit(10).unwrap_or(0) as usize])
        .collect()
 }
 // --- Reading the expression ---------------------------------------------------------------
 #[derive(Debug, Clone, PartialEq)]
 enum Token {
    Number(Rational),
    Variable(char),
    Plus,
    Minus,
    Times,
    /// `/` for a fraction, `:` for a division sign (`:` and `÷`)
    Divide(char),
    Power,
    Open,
    Close,
 }
 fn tokenize(input: &str) -> Option<Vec<Token>> {
    let input = input.trim().trim_end_matches('=').trim_end();
    let chars: Vec<char> = input.chars().collect();
    let mut tokens = Vec::new();
    let mut i = 0;
    while i < chars.len() {
        let c = chars[i];
        if c.is_ascii_digit() {
            let (value, next) = read_number(&chars, i)?;
            tokens.push(Token::Number(value));
            i = next;
            continue;
        }
        if superscript_value(c).is_some() || c == '⁻' {
            // A run of superscript characters is the exponent: x²³ = x^23, 2⁻¹ = 2^(-1)
            let negative = c == '⁻';
            let start = if negative { i + 1 } else { i };
            let mut end = start;
            let mut value: i128 = 0;
            while let Some(digit) = chars.get(end).and_then(|&d| superscript_value(d)) {
                value = value.checked_mul(10)?.checked_add(digit)?;
                end += 1;
            }
            if end == start {
                return None;
            }
            tokens.push(Token::Power);
            if negative {
                tokens.push(Token::Minus);
            }
            tokens.push(Token::Number(Rational::integer(value)));
            i = end;
            continue;
        }
        let token = match c {
            _ if c.is_whitespace() => None,
            '+' => Some(Token::Plus),
            '-' | '−' | '–' => Some(Token::Minus),
            '*' | '·' | '⋅' | '∙' | '×' => Some(Token::Times),
            '/' => Some(Token::Divide('/')),
            ':' | '÷' => Some(Token::Divide(':')),
            '^' => Some(Token::Power),
            '(' | '[' | '{' => Some(Token::Open),
            ')' | ']' | '}' => Some(Token::Close),
            _ if c.is_ascii_alphabetic() => Some(Token::Variable(c)),
            _ => return None,
        };
        tokens.extend(token);
        i += 1;
    }
    Some(tokens)
 }
 fn superscript_value(c: char) -> Option<i128> {
    SUPERSCRIPT_DIGITS
        .iter()
        .position(|&d| d == c)
        .map(|p| p as i128)
 }
 /// Reads `12`, `2,5` or `0.125` from `start`; returns the value and the index after it
 fn read_number(chars: &[char], start: usize) -> Option<(Rational, usize)> {
    let mut i = start;
    let mut num: i128 = 0;
    let mut den: i128 = 1;
    let mut in_fraction = false;
    while i < chars.len() {
        let c = chars[i];
        if let Some(digit) = c.to_digit(10) {
            num = num.checked_mul(10)?.checked_add(digit as i128)?;
            if in_fraction {
                den = den.checked_mul(10)?;
            }
        } else if (c == ',' || c == '.')
            && !in_fraction
            && chars.get(i + 1).is_some_and(|d| d.is_ascii_digit())
        {
            in_fraction = true;
        } else {
            break;
        }
        i += 1;
    }
    Some((Rational::new(num, den)?, i))
 }
 #[derive(Debug, Clone, PartialEq)]
 enum Expr {
    Number(Rational),
    Variable(char),
    Neg(Box<Expr>),
    Add(Box<Expr>, Box<Expr>),
    Sub(Box<Expr>, Box<Expr>),
    Mul(Box<Expr>, Box<Expr>),
    /// With the sign it was written with, for [`display`]
    Div(Box<Expr>, Box<Expr>, char),
    Pow(Box<Expr>, Box<Expr>),
 }
 impl Expr {
    fn eval(&self) -> Option<Polynomial> {
        Some(match self {
            Expr::Number(value) => Polynomial::constant(*value),
            Expr::Variable(name) => Polynomial::variable(*name),
            Expr::Neg(e) => e.eval()?.neg()?,
            Expr::Add(a, b) => a.eval()?.add(&b.eval()?)?,
            Expr::Sub(a, b) => a.eval()?.add(&b.eval()?.neg()?)?,
            Expr::Mul(a, b) => a.eval()?.mul(&b.eval()?)?,
            Expr::Div(a, b, _) => a.eval()?.div(&b.eval()?)?,
            Expr::Pow(a, b) => a.eval()?.pow(&b.eval()?)?,
        })
    }
 }
 impl Expr {
    /// Binding strength for deciding on parentheses: sums < products < signs < powers < atoms
    fn precedence(&self) -> u8 {
        match self {
            Expr::Add(..) | Expr::Sub(..) => 1,
            Expr::Mul(..) | Expr::Div(..) => 2,
            Expr::Neg(_) => 3,
            Expr::Pow(..) => 4,
            Expr::Number(_) | Expr::Variable(_) => 5,
        }
    }
    /// The text of this expression, in parentheses if it binds weaker than `min`
    fn display_at(&self, min: u8, decimal_comma: bool) -> String {
        let text = self.display(decimal_comma);
        if self.precedence() < min {
            format!("({text})")
        } else {
            text
        }
    }
    fn display(&self, decimal_comma: bool) -> String {
        let dc = decimal_comma;
        match self {
            Expr::Number(value) => value.format_abs(dc),
            Expr::Variable(name) => name.to_string(),
            Expr::Neg(e) => format!("−{}", e.display_at(3, dc)),
            Expr::Add(a, b) => format!("{} + {}", a.display_at(1, dc), b.display_at(1, dc)),
            Expr::Sub(a, b) => format!("{} − {}", a.display_at(1, dc), b.display_at(2, dc)),
            Expr::Mul(a, b) => {
                let left = a.display_at(2, dc);
                let right = b.display_at(3, dc);
                // 2x, 3(x + 1), x², but 2 · 3 and x · 2
                let implicit = !matches!(**a, Expr::Neg(_))
                    && (matches!(**b, Expr::Variable(_))
                        || matches!(&**b, Expr::Pow(base, _) if matches!(**base, Expr::Variable(_)))
                        || right.starts_with('('));
                if implicit {
                    format!("{left}{right}")
                } else {
                    format!("{left} · {right}")
                }
            }
            Expr::Div(a, b, sign) => match sign {
                '/' => format!("{}/{}", a.display_at(4, dc), b.display_at(4, dc)),
                _ => format!("{} : {}", a.display_at(2, dc), b.display_at(3, dc)),
            },
            Expr::Pow(base, exponent) => {
                let base = base.display_at(5, dc);
                let integer = |e: &Expr| match e {
                    Expr::Number(v) => v.as_integer().map(|n| superscript(n as u32)),
                    _ => None,
                };
                let small = match &**exponent {
                    Expr::Neg(e) => integer(e).map(|s| format!("⁻{s}")),
                    e => integer(e),
                };
                match small {
                    Some(small) => format!("{base}{small}"),
                    None => format!("{base}^({})", exponent.display(dc)),
                }
            }
        }
    }
 }
 /// Recursive descent with the usual precedence: `+ −` < `· :` and implicit
 /// multiplication < unary minus < `^` (right-associative, so `−2² = −4` and `2^3^2 = 2^9`).
 struct Parser<'a> {
    tokens: &'a [Token],
    pos: usize,
 }
 impl<'a> Parser<'a> {
    fn new(tokens: &'a [Token]) -> Self {
        Parser { tokens, pos: 0 }
    }
    fn parse(mut self) -> Option<Expr> {
        let expr = self.sum()?;
        (self.pos == self.tokens.len()).then_some(expr)
    }
    fn peek(&self) -> Option<&Token> {
        self.tokens.get(self.pos)
    }
    fn eat(&mut self, token: &Token) -> bool {
        let found = self.peek() == Some(token);
        if found {
            self.pos += 1;
        }
        found
    }
    fn sum(&mut self) -> Option<Expr> {
        let mut left = self.product()?;
        loop {
            if self.eat(&Token::Plus) {
                left = Expr::Add(Box::new(left), Box::new(self.product()?));
            } else if self.eat(&Token::Minus) {
                left = Expr::Sub(Box::new(left), Box::new(self.product()?));
            } else {
                return Some(left);
            }
        }
    }
    fn product(&mut self) -> Option<Expr> {
        let mut left = self.unary()?;
        loop {
            if self.eat(&Token::Times) {
                left = Expr::Mul(Box::new(left), Box::new(self.unary()?));
            } else if let Some(&Token::Divide(sign)) = self.peek() {
                self.pos += 1;
                left = Expr::Div(Box::new(left), Box::new(self.unary()?), sign);
            } else if matches!(self.peek(), Some(Token::Variable(_) | Token::Open)) {
                // Implicit multiplication: 2x, 3(x + 1), (a + b)(a − b). Two numbers in a
                // row are not multiplied, they are more likely a misread.
                left = Expr::Mul(Box::new(left), Box::new(self.power()?));
            } else {
                return Some(left);
            }
        }
    }
    fn unary(&mut self) -> Option<Expr> {
        if self.eat(&Token::Minus) {
            return Some(Expr::Neg(Box::new(self.unary()?)));
        }
        if self.eat(&Token::Plus) {
            return self.unary();
        }
        self.power()
    }
    fn power(&mut self) -> Option<Expr> {
        let base = self.atom()?;
        if self.eat(&Token::Power) {
            return Some(Expr::Pow(Box::new(base), Box::new(self.unary()?)));
        }
        Some(base)
    }
    fn atom(&mut self) -> Option<Expr> {
        let token = self.peek()?.clone();
        self.pos += 1;
        match token {
            Token::Number(value) => Some(Expr::Number(value)),
            Token::Variable(name) => Some(Expr::Variable(name)),
            Token::Open => {
                let inner = self.sum()?;
                self.eat(&Token::Close).then_some(inner)
            }
            _ => None,
        }
    }
 }
 #[cfg(test)]
 mod tests {
    use super::*;
    fn de(expression: &str) -> Option<String> {
        solve(expression, true)
    }
    #[test]
    fn arithmetic() {
        assert_eq!(de("2^4 ="), Some("16".into()));
        assert_eq!(de("2⁴="), Some("16".into()));
        assert_eq!(de("1 + 2 · 3"), Some("7".into()));
        assert_eq!(de("(1 + 2) × 3"), Some("9".into()));
        assert_eq!(de("7 − 10"), Some("−3".into()));
        assert_eq!(de("−2^2"), Some("−4".into()));
        assert_eq!(de("(−2)²"), Some("4".into()));
        assert_eq!(de("2^3^2"), Some("512".into()));
        assert_eq!(de("10 : 4"), Some("2,5".into()));
        assert_eq!(de("10 ÷ 4"), Some("2,5".into()));
        assert_eq!(de("3 * [2 + 1]"), Some("9".into()));
    }
    #[test]
    fn decimals_and_fractions() {
        assert_eq!(de("2,5 · 3"), Some("7,5".into()));
        assert_eq!(solve("2.5 * 3", false), Some("7.5".into()));
        assert_eq!(de("0,1 + 0,2"), Some("0,3".into()));
        assert_eq!(de("1 : 3"), Some("1/3".into()));
        assert_eq!(de("1 : 3 · 3"), Some("1".into()));
        assert_eq!(de("2^-2"), Some("0,25".into()));
        assert_eq!(de("2⁻¹"), Some("0,5".into()));
        assert_eq!(de("1 : 8"), Some("0,125".into()));
    }
    #[test]
    fn polynomials() {
        assert_eq!(de("(x + 3)^2 ="), Some("x² + 6x + 9".into()));
        assert_eq!(de("(x+3)²"), Some("x² + 6x + 9".into()));
        assert_eq!(de("(a + b)²"), Some("a² + 2ab + b²".into()));
        assert_eq!(de("(a + b)(a − b)"), Some("a² − b²".into()));
        assert_eq!(de("(a − b)²"), Some("a² − 2ab + b²".into()));
        assert_eq!(de("2x + 3x"), Some("5x".into()));
        assert_eq!(de("x · x"), Some("x²".into()));
        assert_eq!(de("3(x + 1)"), Some("3x + 3".into()));
        assert_eq!(de("(x + 1)^3"), Some("x³ + 3x² + 3x + 1".into()));
        assert_eq!(de("(2x − 1)²"), Some("4x² − 4x + 1".into()));
        assert_eq!(de("x − x"), Some("0".into()));
        assert_eq!(de("(x + 1) : 2"), Some("0,5x + 0,5".into()));
        assert_eq!(de("x : 3"), Some("(1/3)x".into()));
        assert_eq!(de("−(x + 1)"), Some("−x − 1".into()));
        assert_eq!(
            de("(x+1)^10").map(|s| s.starts_with("x¹⁰ + 10x⁹")),
            Some(true)
        );
    }
    #[test]
    fn nothing_to_compute() {
        assert_eq!(de("5"), None);
        assert_eq!(de("x ="), None);
        assert_eq!(de("2x"), None);
        assert_eq!(de("x² + 1"), None);
        assert_eq!(de("2,5"), None);
    }
    #[test]
    fn unreadable_or_not_computable() {
        assert_eq!(de(""), None);
        assert_eq!(de("="), None);
        assert_eq!(de("1 +"), None);
        assert_eq!(de("(1 + 2"), None);
        assert_eq!(de("1 + 2)"), None);
        assert_eq!(de("2 3"), None);
        assert_eq!(de("1 : 0"), None);
        assert_eq!(de("0^-1"), None);
        assert_eq!(de("1 : x"), None);
        assert_eq!(de("x^y"), None);
        assert_eq!(de("x^0,5"), None);
        assert_eq!(de("2 ? 3"), None);
        assert_eq!(de("1,2,3"), None);
    }
    #[test]
    fn displays_expressions() {
        let show = |e: &str| display(e, true).unwrap();
        assert_eq!(show("2^(4)"), "2⁴");
        assert_eq!(show("(x+3)^(2)"), "(x + 3)²");
        assert_eq!(show("2,5·3"), "2,5 · 3");
        assert_eq!(show("9:3"), "9 : 3");
        assert_eq!(show("((x+1)/(2))"), "(x + 1)/2");
        assert_eq!(show("((1)/(2))+((1)/(2·3))"), "1/2 + 1/(2 · 3)");
        assert_eq!(show("2^(-1)"), "2⁻¹");
        assert_eq!(show("2^(x+1)"), "2^(x + 1)");
        assert_eq!(show("3(x+1)"), "3(x + 1)");
        assert_eq!(show("2x^(2)"), "2x²");
        assert_eq!(show("x·2"), "x · 2");
        assert_eq!(show("(a+b)(a-b)"), "(a + b)(a − b)");
        assert_eq!(show("7-(5-2)"), "7 − (5 − 2)");
        assert_eq!(show("-2^(2)"), "−2²");
        assert_eq!(show("(-2)^(2)"), "(−2)²");
        assert_eq!(show("0.5"), "0,5");
        assert!(display("1 +", true).is_none());
    }
    #[test]
    fn overflow_and_limits() {
        assert_eq!(de("10^100"), None);
        assert_eq!(de("2^100000"), None);
        assert_eq!(de("(x + 1)^33"), None);
        assert_eq!(de("(a+b+c+d+e)^8"), None);
        assert_eq!(de("99999999999999999999999999999999999999999999 + 1"), None);
        assert_eq!(de("2^64"), Some("18446744073709551616".into()));
    }
 }
@@ -0,0 +1,465 @@
 //! Computes handwritten math after an `=` (Issue #46, stage 3).
 //!
 //! When the last two strokes on a page form an `=` and the pen then rests for
 //! [`TRIGGER_DELAY`], the strokes left of it are recognized ([`crate::math_ink`]) and computed
 //! ([`crate::math::solve`]). The result is offered next to the `=` as a suggestion that also
 //! shows what was read (`2⁴ = 16`), so that a misread symbol is noticed. Tapping it with the
 //! pen or clicking it inserts the result as a text box; fingers and palms are ignored. Any new
 //! stroke drops the suggestion. Off by default (☰ → Input).
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 use glam::Vec2;
 use crate::document::{Page, Stroke, StrokeTool};
 use crate::math_ink::Recognizer;
 /// Pause after the `=` before its expression is computed; a new stroke cancels it
 pub const TRIGGER_DELAY: Duration = Duration::from_millis(500);
 /// Estimated symbol height relative to the width of the `=`
 const SYMBOL_PER_EQUALS: f32 = 1.3;
 /// Strokes left of the `=` belong to the expression up to a gap of this many symbol heights
 const MAX_GAP: f32 = 2.0;
 /// At most this many strokes are read as the expression
 const MAX_STROKES: usize = 80;
 /// Cap height of the text font relative to its size (Ubuntu: 0.69 em)
 const CAP_HEIGHT_PER_EM: f32 = 0.7;
 /// A result offered next to an `=`
 #[derive(Debug, Clone, PartialEq)]
 pub struct Suggestion {
    pub page_id: u64,
    /// The two strokes of the `=`
    pub equals: [u64; 2],
    /// What was read, written neatly (`2⁴`)
    pub expression: String,
    /// The result (`16`)
    pub result: String,
    /// Where the result goes: left end of the text on the vertical middle of the `=`
    pub anchor: Vec2,
    /// Height of the handwritten digits in page units
    pub symbol_height: f32,
    /// Ink color of the `=`
    pub color: [f32; 4],
 }
 impl Suggestion {
    /// Top left corner and size (em) of a text box that puts the result next to the `=`, as
    /// high as the handwriting
    pub fn text_placement(&self, ascent_per_em: f32) -> (Vec2, f32) {
        let size = self.symbol_height / CAP_HEIGHT_PER_EM;
        // Baseline at the bottom of digits centered on the `=`
        let baseline = self.anchor.y + self.symbol_height / 2.0;
        (
            Vec2::new(self.anchor.x, baseline - ascent_per_em * size),
            size,
        )
    }
 }
 #[derive(Debug, Clone)]
 struct Pending {
    page_id: u64,
    equals: [u64; 2],
    due: Instant,
 }
 /// State of the math assistant: waiting after an `=`, and the suggestion shown
 #[derive(Default, Clone)]
 pub struct MathAssist {
    pub enabled: bool,
    /// Built on first use
    recognizer: Option<Arc<Recognizer>>,
    pending: Option<Pending>,
    suggestion: Option<Suggestion>,
    /// Where the UI drew the suggestion (egui points), for [`Self::take_hit`]
    pub chip_rect: Option<egui::Rect>,
 }
 impl std::fmt::Debug for MathAssist {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("MathAssist")
            .field("enabled", &self.enabled)
            .field("pending", &self.pending)
            .field("suggestion", &self.suggestion)
            .finish_non_exhaustive()
    }
 }
 impl MathAssist {
    /// After a stroke was added to `page`: drops the suggestion and waits if the stroke
    /// completed an `=`
    pub fn stroke_committed(&mut self, page: &Page, now: Instant) {
        self.suggestion = None;
        self.chip_rect = None;
        self.pending = None;
        if !self.enabled {
            return;
        }
        if let Some((a, b)) = equals_at_end(&page.strokes) {
            self.pending = Some(Pending {
                page_id: page.id,
                equals: [page.strokes[a].id, page.strokes[b].id],
                due: now + TRIGGER_DELAY,
            });
        }
    }
    /// When [`Self::update`] has something to do
    pub fn deadline(&self) -> Option<Instant> {
        self.pending.as_ref().map(|p| p.due)
    }
    /// Computes the expression once the pause after the `=` is over (not while a stroke is
    /// being drawn). True if a suggestion appeared.
    pub fn update(
        &mut self,
        page: &Page,
        now: Instant,
        drawing: bool,
        decimal_comma: bool,
    ) -> bool {
        let Some(pending) = self.pending.as_ref() else {
            return false;
        };
        if drawing || now < pending.due {
            return false;
        }
        let pending = self.pending.take().expect("checked above");
        if pending.page_id != page.id || !self.enabled {
            return false;
        }
        let recognizer = self
            .recognizer
            .get_or_insert_with(|| Arc::new(Recognizer::new()));
        self.suggestion = suggest(recognizer, page, pending.equals, decimal_comma);
        self.suggestion.is_some()
    }
    /// The suggestion if it belongs to `page` and its `=` is still there
    pub fn suggestion_for(&self, page: &Page) -> Option<&Suggestion> {
        self.suggestion.as_ref().filter(|s| {
            s.page_id == page.id
                && s.equals
                    .iter()
                    .all(|id| page.strokes.iter().any(|stroke| stroke.id == *id))
        })
    }
    /// The suggestion if `pos` (egui points) is on it; it is then taken away
    pub fn take_hit(&mut self, pos: egui::Pos2) -> Option<Suggestion> {
        if !self.chip_rect.is_some_and(|r| r.contains(pos)) {
            return None;
        }
        self.chip_rect = None;
        self.suggestion.take()
    }
    pub fn set_enabled(&mut self, enabled: bool) {
        self.enabled = enabled;
        if !enabled {
            self.pending = None;
            self.suggestion = None;
            self.chip_rect = None;
        }
    }
 }
 /// Handwriting that can be read: pen strokes (also snapped lines), no highlighter, text or
 /// images
 fn is_ink(stroke: &Stroke) -> bool {
    !stroke.is_object() && stroke.tool != StrokeTool::Highlighter && !stroke.points.is_empty()
 }
 fn positions(stroke: &Stroke) -> Vec<Vec2> {
    stroke.points.iter().map(|s| s.position).collect()
 }
 /// A straight, roughly horizontal stroke: one bar of an `=`
 fn is_bar(stroke: &Stroke) -> bool {
    let size = stroke.aabb.max - stroke.aabb.min;
    let length: f32 = positions(stroke)
        .windows(2)
        .map(|w| w[0].distance(w[1]))
        .sum();
    size.x > 0.0 && size.x >= 2.5 * size.y && length <= 1.3 * size.x
 }
 /// Indices of the last two ink strokes if they form an `=`: two bars of similar length, one
 /// above the other
 fn equals_at_end(strokes: &[Stroke]) -> Option<(usize, usize)> {
    let mut ink = strokes.iter().enumerate().rev().filter(|(_, s)| is_ink(s));
    let (b, second) = ink.next()?;
    let (a, first) = ink.next()?;
    if !is_bar(first) || !is_bar(second) {
        return None;
    }
    let (w1, w2) = (
        first.aabb.max.x - first.aabb.min.x,
        second.aabb.max.x - second.aabb.min.x,
    );
    let (short, long) = (w1.min(w2), w1.max(w2));
    let overlap = first.aabb.max.x.min(second.aabb.max.x) - first.aabb.min.x.max(second.aabb.min.x);
    let dy = ((first.aabb.min.y + first.aabb.max.y) - (second.aabb.min.y + second.aabb.max.y))
        .abs()
        / 2.0;
    (overlap >= 0.5 * short && long <= 2.0 * short && dy >= 0.1 * long && dy <= long)
        .then_some((a, b))
 }
 /// Indices of the strokes left of the `=` that make up its expression, in the order they were
 /// written: ink in a band around the `=`, going left until a wide gap
 fn expression_strokes(strokes: &[Stroke], equals: (usize, usize)) -> Vec<usize> {
    let (e1, e2) = (&strokes[equals.0], &strokes[equals.1]);
    let min = e1.aabb.min.min(e2.aabb.min);
    let max = e1.aabb.max.max(e2.aabb.max);
    let height = (max.x - min.x) * SYMBOL_PER_EQUALS;
    let middle = (min.y + max.y) / 2.0;
    let mut candidates: Vec<usize> = (0..strokes.len())
        .filter(|&i| i != equals.0 && i != equals.1 && is_ink(&strokes[i]))
        .filter(|&i| {
            let s = &strokes[i].aabb;
            let center = (s.min.y + s.max.y) / 2.0;
            (center - middle).abs() <= 2.0 * height
                && s.max.y - s.min.y <= 3.0 * height
                && s.max.x <= min.x + 0.2 * height
        })
        .collect();
    candidates.sort_by(|&a, &b| strokes[b].aabb.max.x.total_cmp(&strokes[a].aabb.max.x));
    let mut left = min.x;
    let mut chosen = Vec::new();
    for i in candidates {
        let s = &strokes[i].aabb;
        if s.max.x < left - MAX_GAP * height || chosen.len() >= MAX_STROKES {
            break;
        }
        left = left.min(s.min.x);
        chosen.push(i);
    }
    chosen.sort_unstable();
    chosen
 }
 /// Reads and computes the expression in front of the `=` made of the strokes `equals`
 fn suggest(
    recognizer: &Recognizer,
    page: &Page,
    equals: [u64; 2],
    decimal_comma: bool,
 ) -> Option<Suggestion> {
    let strokes = &page.strokes;
    let index = |id: u64| strokes.iter().position(|s| s.id == id);
    let pair = (index(equals[0])?, index(equals[1])?);
    let mut chosen = expression_strokes(strokes, pair);
    if chosen.is_empty() {
        return None;
    }
    chosen.extend([pair.0, pair.1]);
    let points: Vec<Vec<Vec2>> = chosen.iter().map(|&i| positions(&strokes[i])).collect();
    let recognition = recognizer.recognize(&points)?;
    // The `=` must be read as the last symbol, from exactly its two strokes
    let last = recognition.symbols.last()?;
    let equals_strokes = [points.len() - 2, points.len() - 1];
    let mut last_strokes = last.strokes.clone();
    last_strokes.sort_unstable();
    if last.ch != '=' || last_strokes != equals_strokes {
        return None;
    }
    // In a chain like `x = 2 + 3 =` only the part after the previous `=` is computed
    let text = recognition.text.strip_suffix('=')?;
    let expression = text.rsplit('=').next()?;
    // A dot or comma that was written decides the separator of the result
    let decimal_comma = if expression.contains(',') {
        true
    } else if expression.contains('.') {
        false
    } else {
        decimal_comma
    };
    let result = crate::math::solve(expression, decimal_comma)?;
    let shown = crate::math::display(expression, decimal_comma)?;
    let (e1, e2) = (&strokes[pair.0], &strokes[pair.1]);
    let right = e1.aabb.max.x.max(e2.aabb.max.x);
    let middle = (e1.aabb.min.y.min(e2.aabb.min.y) + e1.aabb.max.y.max(e2.aabb.max.y)) / 2.0;
    let mut heights: Vec<f32> = recognition
        .symbols
        .iter()
        .filter(|s| s.ch.is_ascii_digit() || s.ch.is_ascii_alphabetic())
        .map(|s| s.max.y - s.min.y)
        .collect();
    heights.sort_by(f32::total_cmp);
    let width = right - e1.aabb.min.x.min(e2.aabb.min.x);
    let symbol_height = heights
        .last()
        .copied()
        .unwrap_or(width * SYMBOL_PER_EQUALS)
        .max(1.0);
    Some(Suggestion {
        page_id: page.id,
        equals,
        expression: shown,
        result,
        anchor: Vec2::new(right + 0.4 * symbol_height, middle),
        symbol_height,
        color: e2.color,
    })
 }
 #[cfg(test)]
 mod tests {
    use super::*;
    use crate::document::StylusSample;
    use crate::math_ink::tests::{write_line, Jitter};
    const BLACK: [f32; 4] = [0.0, 0.0, 0.0, 1.0];
    fn stroke(id: u64, points: &[Vec2]) -> Stroke {
        let samples = points
            .iter()
            .enumerate()
            .map(|(i, &position)| StylusSample {
                position,
                pressure: 0.5,
                timestamp: i as f64 * 0.01,
            })
            .collect();
        Stroke::new(id, samples, Vec::new(), BLACK)
    }
    /// A page with `text` written at `origin`, scaled by `scale`
    fn page_with(lines: &[(&str, Vec2)], scale: f32) -> Page {
        let mut page = Page::new(7, crate::document::PageBackground::Blank);
        let mut id = 1;
        for (seed, (text, origin)) in lines.iter().enumerate() {
            for points in write_line(text, &mut Jitter(seed as u64 + 3)) {
                let points: Vec<Vec2> = points.iter().map(|p| *origin + *p * scale).collect();
                page.add_stroke(stroke(id, &points));
                id += 1;
            }
        }
        page
    }
    fn run(page: &Page) -> Option<Suggestion> {
        let mut assist = MathAssist {
            enabled: true,
            ..Default::default()
        };
        let start = Instant::now();
        assist.stroke_committed(page, start);
        assert!(!assist.update(page, start, false, true), "too early");
        assist.update(page, start + TRIGGER_DELAY, false, true);
        assist.suggestion_for(page).cloned()
    }
    #[test]
    fn suggests_result_after_equals() {
        let page = page_with(&[("(x+3)^2=", Vec2::new(100.0, 200.0))], 3.0);
        let suggestion = run(&page).unwrap();
        assert_eq!(suggestion.expression, "(x + 3)²");
        assert_eq!(suggestion.result, "x² + 6x + 9");
        let equals_right = page
            .strokes
            .iter()
            .rev()
            .take(2)
            .map(|s| s.aabb.max.x)
            .fold(f32::MIN, f32::max);
        assert!(suggestion.anchor.x > equals_right);
        // The handwriting is 14 units high, scaled by 3
        assert!(
            (suggestion.symbol_height - 42.0).abs() < 6.0,
            "{suggestion:?}"
        );
    }
    #[test]
    fn ignores_writing_far_to_the_left_and_on_other_lines() {
        let page = page_with(
            &[
                ("7", Vec2::new(0.0, 200.0)),
                ("5·5", Vec2::new(0.0, 300.0)),
                ("2^4=", Vec2::new(150.0, 200.0)),
            ],
            2.0,
        );
        let suggestion = run(&page).unwrap();
        assert_eq!(suggestion.expression, "2⁴");
        assert_eq!(suggestion.result, "16");
    }
    #[test]
    fn computes_the_last_part_of_a_chain() {
        let page = page_with(&[("x=2·3=", Vec2::new(0.0, 0.0))], 2.0);
        assert_eq!(run(&page).unwrap().result, "6");
    }
    #[test]
    fn nothing_without_equals_or_when_disabled() {
        let page = page_with(&[("2+3", Vec2::ZERO)], 2.0);
        assert!(run(&page).is_none());
        let page = page_with(&[("2+3=", Vec2::ZERO)], 2.0);
        let mut assist = MathAssist::default();
        assist.stroke_committed(&page, Instant::now());
        assert!(assist.deadline().is_none());
    }
    #[test]
    fn new_stroke_or_removed_equals_drops_the_suggestion() {
        let mut page = page_with(&[("1+1=", Vec2::ZERO)], 2.0);
        let mut assist = MathAssist {
            enabled: true,
            ..Default::default()
        };
        let start = Instant::now();
        assist.stroke_committed(&page, start);
        // A stroke still being drawn when the time is up: nothing yet
        assert!(!assist.update(&page, start + TRIGGER_DELAY, true, true));
        assert!(assist.update(&page, start + TRIGGER_DELAY, false, true));
        assert_eq!(assist.suggestion_for(&page).unwrap().result, "2");
        let last = page.strokes.last().unwrap().id;
        page.remove_strokes_by_ids(&[last]);
        assert!(assist.suggestion_for(&page).is_none());
        assist.stroke_committed(&page, start);
        assert!(assist.suggestion.is_none());
    }
    #[test]
    fn hit_takes_the_suggestion() {
        let page = page_with(&[("1+1=", Vec2::ZERO)], 2.0);
        let mut assist = MathAssist {
            enabled: true,
            ..Default::default()
        };
        let start = Instant::now();
        assist.stroke_committed(&page, start);
        assist.update(&page, start + TRIGGER_DELAY, false, true);
        assist.chip_rect = Some(egui::Rect::from_min_size(
            egui::pos2(10.0, 10.0),
            egui::vec2(50.0, 20.0),
        ));
        assert!(assist.take_hit(egui::pos2(5.0, 5.0)).is_none());
        assert_eq!(assist.take_hit(egui::pos2(20.0, 20.0)).unwrap().result, "2");
        assert!(assist.take_hit(egui::pos2(20.0, 20.0)).is_none());
    }
    #[test]
    fn result_text_sits_on_the_baseline() {
        let suggestion = Suggestion {
            page_id: 1,
            equals: [1, 2],
            expression: "1 + 1".into(),
            result: "2".into(),
            anchor: Vec2::new(100.0, 50.0),
            symbol_height: 14.0,
            color: BLACK,
        };
        let (top_left, size) = suggestion.text_placement(0.9);
        assert!((size - 20.0).abs() < 0.01);
        // Baseline (top + ascent) at the bottom of digits centered on the `=`
        assert!((top_left.y + 0.9 * size - 57.0).abs() < 0.01);
        assert_eq!(top_left.x, 100.0);
    }
 }
@@ -17,11 +17,39 @@ mod wayland;
 #[cfg(target_os = "linux")]
 pub use wayland::KeyboardRequester;
-/// Elsewhere the system shows the on-screen keyboard by itself; nothing to request.
+/// Android: the soft keyboard is shown only when asked to (Issue #42). Its text comes through
-#[cfg(not(target_os = "linux"))]
+/// the activity's input connection (`android_bridge`); keys like Enter or Backspace may also
 /// arrive as key events through winit.
 #[cfg(target_os = "android")]
 pub struct KeyboardRequester;
-#[cfg(not(target_os = "linux"))]
+#[cfg(target_os = "android")]
 impl KeyboardRequester {
    /// # Safety
    /// Nothing to uphold; `unsafe` like the Wayland version.
    pub unsafe fn for_window(_window: &winit::window::Window) -> Option<Self> {
        Some(Self)
    }
    pub fn request(&mut self) {
        crate::android_bridge::show_keyboard(true);
    }
    pub fn release(&mut self) {
        crate::android_bridge::show_keyboard(false);
    }
    /// Typed text and deletions; taking them is left to the app's frame (see `app.rs`)
    pub fn take_deletions(&mut self) -> Vec<egui::Event> {
        Vec::new()
    }
 }
 /// Elsewhere the system shows the on-screen keyboard by itself; nothing to request.
 #[cfg(not(any(target_os = "linux", target_os = "android")))]
 pub struct KeyboardRequester;
 #[cfg(not(any(target_os = "linux", target_os = "android")))]
 impl KeyboardRequester {
    /// # Safety
    /// Nothing to uphold; `unsafe` like the Wayland version.
@@ -31,6 +59,8 @@ impl KeyboardRequester {
    pub fn request(&mut self) {}
    pub fn release(&mut self) {}
    pub fn take_deletions(&mut self) -> Vec<egui::Event> {
        Vec::new()
    }
@@ -75,6 +105,30 @@ pub fn deletion_key_events(back: u32, forward: u32) -> Vec<egui::Event> {
        .collect()
 }
 /// egui input for committed text: line breaks become the Enter key, as egui's text fields
 /// take them only that way.
 pub fn committed_text_events(text: &str) -> Vec<egui::Event> {
    let mut events = Vec::new();
    for (i, line) in text.split('\n').enumerate() {
        if i > 0 {
            for pressed in [true, false] {
                events.push(egui::Event::Key {
                    key: egui::Key::Enter,
                    physical_key: None,
                    pressed,
                    repeat: false,
                    modifiers: egui::Modifiers::NONE,
                });
            }
        }
        let line = line.trim_end_matches('\r');
        if !line.is_empty() {
            events.push(egui::Event::Text(line.to_string()));
        }
    }
    events
 }
 /// Entscheidet, ob die Bildschirmtastatur angefordert wird: sobald ein Textfeld den Fokus
 /// bekommt und erneut bei jedem Antippen des fokussierten Felds (falls die Tastatur inzwischen
 /// zugeklappt wurde).
@@ -165,6 +219,20 @@ mod tests {
        assert!(deletion_key_events(0, 0).is_empty());
    }
    #[test]
    fn committed_line_breaks_become_enter() {
        let events = committed_text_events("ab\nc\n");
        let kinds: Vec<String> = events
            .iter()
            .map(|e| match e {
                egui::Event::Text(t) => t.clone(),
                egui::Event::Key { pressed: true, .. } => "⏎".into(),
                _ => "-".into(),
            })
            .collect();
        assert_eq!(kinds, ["ab", "⏎", "-", "c", "⏎", "-"]);
    }
    #[test]
    fn no_request_without_focused_text_field() {
        assert!(!should_request(false, false, true));
@@ -92,6 +92,10 @@ impl KeyboardRequester {
        }
    }
    /// The text field lost focus. Nothing to do: the compositor hides the keyboard once
    /// winit disables text input.
    pub fn release(&mut self) {}
    /// Tastendrücke für das seit dem letzten Aufruf gewünschte Löschen (vor `begin_frame`
    /// aufrufen und an die egui-Eingabe anhängen)
    pub fn take_deletions(&mut self) -> Vec<egui::Event> {
@@ -0,0 +1,382 @@
 //! Pen input independent of the platform (Issue #44).
 //!
 //! On the desktop the pen comes from octotablet (Wayland/X11 tablet protocols, Windows Ink),
 //! on Android as touch samples with the tool type stylus or eraser, which the patched winit
 //! hands over separately (`winit::platform::android::take_pen_samples`). Both are turned into
 //! the same [`PenInput`] events, which the app handles in one place.
 use std::time::{Duration, Instant};
 /// What happened to the pen.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum PenEvent {
    /// Pen comes into range (hovers above the screen)
    In,
    /// Pen left the range
    Out,
    /// Tip touches the screen (at the position of the last `Pose`)
    Down,
    /// Tip lifted
    Up,
    /// Position in logical pixels; pressure 0..=1 if known
    Pose {
        position: [f32; 2],
        pressure: Option<f32>,
    },
    /// Pen button pressed or released; `key` identifies the button across sessions
    Button { key: u64, pressed: bool },
 }
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct PenInput {
    /// Identifies the pen (several pens can be in use on the desktop)
    pub tool: u64,
    /// Eraser end of the pen
    pub is_eraser: bool,
    pub event: PenEvent,
 }
 fn hash_of(value: impl std::hash::Hash) -> u64 {
    use std::hash::Hasher;
    // DefaultHasher::new() uses fixed keys: same input, same value in every session
    let mut hasher = std::collections::hash_map::DefaultHasher::new();
    value.hash(&mut hasher);
    hasher.finish()
 }
 /// Turns octotablet's events into [`PenInput`]s, with each `Down` after the `Pose` of the
 /// same frame (see [`crate::platform::down_after_pose`]).
 #[cfg(not(target_os = "android"))]
 pub fn from_octotablet<'a>(
    events: impl IntoIterator<Item = octotablet::events::Event<'a>>,
 ) -> Vec<PenInput> {
    use octotablet::events::{Event, ToolEvent};
    let inputs = events.into_iter().filter_map(|event| {
        let Event::Tool { tool, event } = event else {
            return None;
        };
        let event = match event {
            ToolEvent::In { .. } => PenEvent::In,
            ToolEvent::Out | ToolEvent::Removed => PenEvent::Out,
            ToolEvent::Down => PenEvent::Down,
            ToolEvent::Up => PenEvent::Up,
            ToolEvent::Pose(pose) => PenEvent::Pose {
                position: pose.position,
                pressure: pose.pressure.get(),
            },
            ToolEvent::Button { button_id, pressed } => PenEvent::Button {
                key: hash_of(button_id),
                pressed,
            },
            _ => return None,
        };
        Some(PenInput {
            tool: hash_of(tool.id()),
            is_eraser: tool.tool_type == Some(octotablet::tool::Type::Eraser),
            event,
        })
    });
    crate::platform::down_after_pose(
        inputs,
        |i| i.event == PenEvent::Down,
        |i| matches!(i.event, PenEvent::Pose { .. }),
    )
 }
 /// What an Android pen sample reports (mirrors `winit::platform::android::PenAction`).
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum SampleAction {
    HoverEnter,
    HoverMove,
    HoverExit,
    Down,
    Move,
    Up,
    Cancel,
 }
 /// One Android pen sample (mirrors `winit::platform::android::PenSample`).
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Sample {
    pub action: SampleAction,
    /// Physical pixels
    pub x: f32,
    pub y: f32,
    pub pressure: f32,
    pub eraser: bool,
    /// `MotionEvent.getButtonState()`
    pub buttons: u32,
 }
 #[cfg(target_os = "android")]
 impl From<winit::platform::android::PenSample> for Sample {
    fn from(s: winit::platform::android::PenSample) -> Self {
        use winit::platform::android::PenAction as A;
        Self {
            action: match s.action {
                A::HoverEnter => SampleAction::HoverEnter,
                A::HoverMove => SampleAction::HoverMove,
                A::HoverExit => SampleAction::HoverExit,
                A::Down => SampleAction::Down,
                A::Move => SampleAction::Move,
                A::Up => SampleAction::Up,
                A::Cancel => SampleAction::Cancel,
            },
            x: s.x,
            y: s.y,
            pressure: s.pressure,
            eraser: s.eraser,
            buttons: s.buttons,
        }
    }
 }
 /// The two pen buttons of Android's `MotionEvent` (`BUTTON_STYLUS_PRIMARY`/`SECONDARY`).
 const ANDROID_BUTTONS: [(u32, &str); 2] = [
    (0x20, "android-stylus-primary"),
    (0x40, "android-stylus-secondary"),
 ];
 /// How long the pen may be out of sight before it counts as gone. Android reports
 /// `HoverExit` right before the tip touches down, and pens without hover report nothing
 /// after lifting.
 const ANDROID_OUT_DELAY: Duration = Duration::from_millis(150);
 /// Turns Android pen samples into [`PenInput`]s.
 #[derive(Debug, Default)]
 pub struct AndroidPen {
    in_range: bool,
    down: bool,
    eraser: bool,
    buttons: u32,
    /// Since when the pen is neither hovering nor touching
    gone_since: Option<Instant>,
 }
 impl AndroidPen {
    /// The single pen Android reports
    const TOOL: u64 = 1;
    fn push(&self, out: &mut Vec<PenInput>, event: PenEvent) {
        out.push(PenInput {
            tool: Self::TOOL,
            is_eraser: self.eraser,
            event,
        });
    }
    /// Events for `samples` (in this order); `scale` converts physical to logical pixels.
    pub fn convert(&mut self, samples: &[Sample], scale: f32, now: Instant) -> Vec<PenInput> {
        let mut out = Vec::new();
        for sample in samples {
            self.eraser = sample.eraser;
            for (mask, name) in ANDROID_BUTTONS {
                let pressed = sample.buttons & mask != 0;
                if pressed != (self.buttons & mask != 0) {
                    self.push(
                        &mut out,
                        PenEvent::Button {
                            key: hash_of(name),
                            pressed,
                        },
                    );
                }
            }
            self.buttons = sample.buttons;
            let position = [sample.x / scale, sample.y / scale];
            let touching = Some(sample.pressure.clamp(0.0, 1.0));
            match sample.action {
                SampleAction::HoverEnter | SampleAction::HoverMove => {
                    self.gone_since = None;
                    self.enter(&mut out);
                    let pose = PenEvent::Pose {
                        position,
                        pressure: None,
                    };
                    self.push(&mut out, pose);
                }
                SampleAction::HoverExit => {
                    if !self.down {
                        self.gone_since.get_or_insert(now);
                    }
                }
                SampleAction::Down => {
                    self.gone_since = None;
                    self.enter(&mut out);
                    let pose = PenEvent::Pose {
                        position,
                        pressure: touching,
                    };
                    self.push(&mut out, pose);
                    if !self.down {
                        self.down = true;
                        self.push(&mut out, PenEvent::Down);
                    }
                }
                SampleAction::Move => {
                    self.gone_since = None;
                    self.enter(&mut out);
                    let pressure = if self.down { touching } else { None };
                    self.push(&mut out, PenEvent::Pose { position, pressure });
                }
                SampleAction::Up | SampleAction::Cancel => {
                    if self.down {
                        if sample.action == SampleAction::Up {
                            let pose = PenEvent::Pose {
                                position,
                                pressure: touching,
                            };
                            self.push(&mut out, pose);
                        }
                        self.down = false;
                        self.push(&mut out, PenEvent::Up);
                    }
                    self.gone_since = Some(now);
                }
            }
        }
        out.extend(self.poll(now));
        out
    }
    fn enter(&mut self, out: &mut Vec<PenInput>) {
        if !self.in_range {
            self.in_range = true;
            self.push(out, PenEvent::In);
        }
    }
    /// `Out` once the pen has been gone for a moment; call regularly while it is in range.
    pub fn poll(&mut self, now: Instant) -> Vec<PenInput> {
        let mut out = Vec::new();
        let gone = self
            .gone_since
            .is_some_and(|since| now.duration_since(since) >= ANDROID_OUT_DELAY);
        if gone && self.in_range && !self.down {
            self.in_range = false;
            self.gone_since = None;
            if self.buttons != 0 {
                for (mask, name) in ANDROID_BUTTONS {
                    if self.buttons & mask != 0 {
                        self.push(
                            &mut out,
                            PenEvent::Button {
                                key: hash_of(name),
                                pressed: false,
                            },
                        );
                    }
                }
                self.buttons = 0;
            }
            self.push(&mut out, PenEvent::Out);
        }
        out
    }
 }
 #[cfg(test)]
 mod tests {
    use super::*;
    fn sample(action: SampleAction, x: f32, pressure: f32, buttons: u32) -> Sample {
        Sample {
            action,
            x,
            y: 10.0,
            pressure,
            eraser: false,
            buttons,
        }
    }
    fn kinds(inputs: &[PenInput]) -> Vec<&'static str> {
        inputs
            .iter()
            .map(|i| match i.event {
                PenEvent::In => "in",
                PenEvent::Out => "out",
                PenEvent::Down => "down",
                PenEvent::Up => "up",
                PenEvent::Pose { pressure: None, .. } => "hover",
                PenEvent::Pose { .. } => "pose",
                PenEvent::Button { pressed: true, .. } => "button-down",
                PenEvent::Button { .. } => "button-up",
            })
            .collect()
    }
    #[test]
    fn test_android_stroke_with_hover() {
        use SampleAction::*;
        let mut pen = AndroidPen::default();
        let t = Instant::now();
        let ms = |n| t + Duration::from_millis(n);
        let out = pen.convert(&[sample(HoverEnter, 20.0, 0.0, 0)], 2.0, t);
        assert_eq!(kinds(&out), ["in", "hover"]);
        assert_eq!(
            out[1].event,
            PenEvent::Pose {
                position: [10.0, 5.0],
                pressure: None
            }
        );
        // Android ends the hover right before the tip touches: no Out in between
        let out = pen.convert(&[sample(HoverExit, 20.0, 0.0, 0)], 2.0, ms(5));
        assert!(out.is_empty());
        let out = pen.convert(
            &[sample(Down, 20.0, 0.4, 0), sample(Move, 30.0, 0.5, 0)],
            2.0,
            ms(10),
        );
        assert_eq!(kinds(&out), ["pose", "down", "pose"]);
        assert!(pen.poll(ms(500)).is_empty(), "still touching");
        let out = pen.convert(&[sample(Up, 30.0, 0.0, 0)], 2.0, ms(600));
        assert_eq!(kinds(&out), ["pose", "up"]);
        let out = pen.convert(&[sample(HoverEnter, 30.0, 0.0, 0)], 2.0, ms(610));
        assert_eq!(kinds(&out), ["hover"]);
        pen.convert(&[sample(HoverExit, 30.0, 0.0, 0)], 2.0, ms(700));
        assert!(pen.poll(ms(750)).is_empty());
        assert_eq!(kinds(&pen.poll(ms(900))), ["out"]);
    }
    #[test]
    fn test_android_pen_without_hover_leaves_after_lifting() {
        use SampleAction::*;
        let mut pen = AndroidPen::default();
        let t = Instant::now();
        let out = pen.convert(&[sample(Down, 0.0, 0.7, 0)], 1.0, t);
        assert_eq!(kinds(&out), ["in", "pose", "down"]);
        pen.convert(&[sample(Up, 0.0, 0.0, 0)], 1.0, t);
        assert_eq!(kinds(&pen.poll(t + Duration::from_millis(200))), ["out"]);
    }
    #[test]
    fn test_android_buttons_and_cancel() {
        use SampleAction::*;
        let mut pen = AndroidPen::default();
        let t = Instant::now();
        let out = pen.convert(
            &[
                sample(HoverMove, 0.0, 0.0, 0x20),
                sample(Down, 0.0, 0.5, 0x20),
                sample(Cancel, 0.0, 0.0, 0x20),
            ],
            1.0,
            t,
        );
        assert_eq!(
            kinds(&out),
            ["button-down", "in", "hover", "pose", "down", "up"]
        );
        // Pen gone with the button still held: released before Out
        let out = pen.poll(t + Duration::from_millis(200));
        assert_eq!(kinds(&out), ["button-up", "out"]);
    }
 }
@@ -127,6 +127,147 @@ where
    event_loop.run(handler)
 }
 /// The Android activity, for calls winit doesn't offer (soft keyboard, Issue #42).
 #[cfg(target_os = "android")]
 static ANDROID_APP: std::sync::OnceLock<winit::platform::android::activity::AndroidApp> =
    std::sync::OnceLock::new();
 /// Remembers the activity; called once by `android_main`.
 #[cfg(target_os = "android")]
 pub fn set_android_app(app: winit::platform::android::activity::AndroidApp) {
    let _ = ANDROID_APP.set(app);
 }
 #[cfg(target_os = "android")]
 pub fn android_app() -> Option<winit::platform::android::activity::AndroidApp> {
    ANDROID_APP.get().cloned()
 }
 /// Makes an exported file available to the user. Desktop: it already is (the path is
 /// returned). Android: copied to `Download/ink-notes` through the MediaStore (Android 10 and
 /// newer), as other apps can't see the app's own folder; older versions keep it there.
 pub fn publish_export(path: std::path::PathBuf) -> Result<std::path::PathBuf, String> {
    #[cfg(target_os = "android")]
    match android_files::publish_to_downloads(&path) {
        Ok(location) => {
            let _ = std::fs::remove_file(&path);
            return Ok(location);
        }
        Err(err) => log::warn!("export not copied to Downloads: {err}"),
    }
    Ok(path)
 }
 #[cfg(target_os = "android")]
 mod android_files {
    use jni::objects::{JObject, JValue};
    use jni::JNIEnv;
    use std::path::{Path, PathBuf};
    /// Folder below the shared storage the exports go to
    const RELATIVE_PATH: &str = "Download/ink-notes";
    fn mime_type(path: &Path) -> &'static str {
        match path.extension().and_then(|e| e.to_str()) {
            Some("pdf") => "application/pdf",
            Some("png") => "image/png",
            Some("svg") => "image/svg+xml",
            _ => "application/octet-stream",
        }
    }
    pub fn publish_to_downloads(path: &Path) -> Result<PathBuf, String> {
        let app = super::android_app().ok_or("no activity")?;
        let name = path
            .file_name()
            .and_then(|n| n.to_str())
            .ok_or("invalid file name")?
            .to_string();
        let bytes = std::fs::read(path).map_err(|e| e.to_string())?;
        // Safety: pointers to the VM and the activity (a global reference) that live as long
        // as the app
        let vm =
            unsafe { jni::JavaVM::from_raw(app.vm_as_ptr().cast()) }.map_err(|e| e.to_string())?;
        let mut env = vm.attach_current_thread().map_err(|e| e.to_string())?;
        let activity = unsafe { JObject::from_raw(app.activity_as_ptr().cast()) };
        let result = insert(&mut env, &activity, &name, mime_type(path), &bytes);
        if env.exception_check().unwrap_or(false) {
            let _ = env.exception_describe();
            let _ = env.exception_clear();
        }
        result.map_err(|e| e.to_string())?;
        Ok(Path::new(RELATIVE_PATH).join(name))
    }
    fn insert(
        env: &mut JNIEnv,
        activity: &JObject,
        name: &str,
        mime: &str,
        bytes: &[u8],
    ) -> jni::errors::Result<()> {
        let sdk = env
            .get_static_field("android/os/Build$VERSION", "SDK_INT", "I")?
            .i()?;
        if sdk < 29 {
            return Err(jni::errors::Error::JniCall(jni::errors::JniError::Unknown));
        }
        let values = env.new_object("android/content/ContentValues", "()V", &[])?;
        for (key, value) in [
            ("_display_name", name),
            ("mime_type", mime),
            ("relative_path", RELATIVE_PATH),
        ] {
            let key = env.new_string(key)?;
            let value = env.new_string(value)?;
            env.call_method(
                &values,
                "put",
                "(Ljava/lang/String;Ljava/lang/String;)V",
                &[JValue::Object(&key), JValue::Object(&value)],
            )?;
        }
        let resolver = env
            .call_method(
                activity,
                "getContentResolver",
                "()Landroid/content/ContentResolver;",
                &[],
            )?
            .l()?;
        let collection = env
            .get_static_field(
                "android/provider/MediaStore$Downloads",
                "EXTERNAL_CONTENT_URI",
                "Landroid/net/Uri;",
            )?
            .l()?;
        let uri = env
            .call_method(
                &resolver,
                "insert",
                "(Landroid/net/Uri;Landroid/content/ContentValues;)Landroid/net/Uri;",
                &[JValue::Object(&collection), JValue::Object(&values)],
            )?
            .l()?;
        if uri.is_null() {
            return Err(jni::errors::Error::NullPtr("MediaStore insert"));
        }
        let stream = env
            .call_method(
                &resolver,
                "openOutputStream",
                "(Landroid/net/Uri;)Ljava/io/OutputStream;",
                &[JValue::Object(&uri)],
            )?
            .l()?;
        let array = env.byte_array_from_slice(bytes)?;
        env.call_method(&stream, "write", "([B)V", &[JValue::Object(&array)])?;
        env.call_method(&stream, "close", "()V", &[])?;
        Ok(())
    }
 }
 /// Gives the window the app id (Wayland: app_id, X11: WM_CLASS), so that dock and task bar
 /// show the app icon for it.
 pub fn with_app_id(
@@ -232,6 +232,8 @@ pub struct UiSettings {
    /// Folder of the notebooks, e.g. inside a Nextcloud folder; default location if unset
    /// (Issue #49)
    pub storage_dir: Option<PathBuf>,
    /// Compute handwritten math after `=` (Issue #46)
    pub math_assist: bool,
 }
 impl Default for UiSettings {
@@ -253,6 +255,7 @@ impl Default for UiSettings {
            language: None,
            eraser_radius_mm: 3.0,
            storage_dir: None,
            math_assist: false,
        }
    }
 }
@@ -350,6 +353,7 @@ mod tests {
            language: Some(Language::English),
            eraser_radius_mm: 6.0,
            storage_dir: Some(PathBuf::from("/home/pia/Nextcloud/ink-notes")),
            math_assist: true,
        };
        settings.save_to(&path).unwrap();
        assert_eq!(UiSettings::load_from(&path), settings);
@@ -317,6 +317,8 @@ pub enum UiAction {
    UnlockCorruptedPage(u64),
    /// Werkzeugleiste an die andere Fensterseite verlegen (wird gespeichert)
    SetSidebarSide(SidebarSide),
    /// Compute handwritten math after `=` on or off (Issue #46)
    SetMathAssist(bool),
    /// Sprache der Oberfläche; `None` = Sprache des Systems
    SetLanguage(Option<crate::i18n::Language>),
    /// Papierfarbe der Anzeige und Aufhellen dunkler Tinte (wird gespeichert)
@@ -413,6 +415,8 @@ pub struct UiState {
    pub update_modal_rect: Option<egui::Rect>,
    /// Steuert, ob Touch-Eingaben mit einem Finger zeichnen oder das Dokument verschieben (Default: false = reine Gesten-Navigation & Zoom)
    pub touch_draw_enabled: bool,
    /// Computes handwritten math after an `=` (Issue #46)
    pub math: crate::math_assist::MathAssist,
    /// Zuletzt gelöschtes Notizbuch für Rückgängig während der Sitzung (Papierkorb-Pfad, Titel)
    pub last_deleted_notebook: Option<(std::path::PathBuf, String)>,
    /// Stifte der Werkzeugleiste (Farbe und Stärke) und der gewählte davon; `pen_color` und
@@ -546,6 +550,7 @@ impl Default for UiState {
            show_updater_config: false,
            update_modal_rect: None,
            touch_draw_enabled: false,
            math: crate::math_assist::MathAssist::default(),
            last_deleted_notebook: None,
            pen_presets: DEFAULT_PEN_PRESETS,
            active_pen: 0,
@@ -690,6 +695,11 @@ impl UiState {
    fn open_file_picker(&mut self, kind: PickerKind) {
        let dir = self.last_picker_dir.clone();
        self.close_overlays();
        // Android: the app can't look into other apps' folders; the system dialog can
        #[cfg(target_os = "android")]
        if crate::android_bridge::pick_file(kind) {
            return;
        }
        self.file_picker = Some(FilePicker::open(kind, dir.as_deref()));
    }
@@ -1647,6 +1657,57 @@ fn text_style_buttons(ui: &mut egui::Ui, btn: f32, state: &mut UiState) {
 /// Bearbeitung eines Textfelds: egui-Textfeld an der Stelle und in der Größe des Felds auf
 /// dem Blatt (ungedreht), mit derselben Schrift. Esc beendet die Bearbeitung.
 /// The result offered next to a handwritten `=` (Issue #46): what was read and the result,
 /// e.g. `2⁴ = 16`. Not interactive for egui, so that fingers and palms pass through to the
 /// page; the pen and the mouse take it via [`crate::math_assist::MathAssist::take_hit`].
 fn math_suggestion(ctx: &egui::Context, state: &mut UiState, notebook: &Notebook) {
    state.math.chip_rect = None;
    if state.view_mode {
        return;
    }
    let (Some(view), Some(suggestion)) = (
        state.page_view,
        state.math.suggestion_for(notebook.current_page()).cloned(),
    ) else {
        return;
    };
    let size = (suggestion.symbol_height * view.scale * 0.8).clamp(14.0, 48.0);
    let response = egui::Area::new(egui::Id::new("math_suggestion"))
        .fixed_pos(view.to_screen(suggestion.anchor))
        .pivot(egui::Align2::LEFT_CENTER)
        .order(egui::Order::Foreground)
        .interactable(false)
        .show(ctx, |ui| {
            egui::Frame::none()
                .fill(egui::Color32::from_rgba_unmultiplied(30, 34, 44, 235))
                .stroke(egui::Stroke::new(
                    1.5_f32,
                    egui::Color32::from_rgb(70, 130, 230),
                ))
                .rounding(size * 0.4)
                .inner_margin(egui::vec2(size * 0.45, size * 0.2))
                .show(ui, |ui| {
                    ui.horizontal(|ui| {
                        ui.spacing_mut().item_spacing.x = size * 0.25;
                        ui.label(
                            egui::RichText::new(format!("{} =", suggestion.expression))
                                .size(size * 0.7)
                                .color(egui::Color32::from_gray(170)),
                        );
                        ui.label(
                            egui::RichText::new(&suggestion.result)
                                .size(size)
                                .strong()
                                .color(egui::Color32::WHITE),
                        );
                    });
                });
        })
        .response;
    // A little larger than drawn, as the pen does not hit exactly
    state.math.chip_rect = Some(response.rect.expand(6.0));
 }
 fn text_edit_overlay(ctx: &egui::Context, state: &mut UiState) {
    let adapt = state.adapt_ink_colors && state.paper_theme.is_dark();
    let (Some(view), Some(edit)) = (state.page_view, state.text_edit.as_mut()) else {
@@ -3145,6 +3206,7 @@ pub fn render_ui(
    space_preview(ctx, state, notebook);
    ruler_overlay(ctx, state);
    text_edit_overlay(ctx, state);
    math_suggestion(ctx, state, notebook);
    context_menu(ctx, state, &mut actions);
    let mut pen_btn_rect = None;
@@ -4378,6 +4440,15 @@ pub fn render_ui(
                            .on_hover_text(
                                t!("Aus: ein Finger verschiebt, zwei Finger zoomen (empfohlen mit Stift).\nAn: ein Finger zeichnet."),
                            );
                            let mut math = state.math.enabled;
                            if ui
                                .checkbox(&mut math, t!("Formeln nach „=“ ausrechnen"))
                                .on_hover_text(t!("Nach einem handgeschriebenen „=“ erscheint das Ergebnis daneben, z. B. 2⁴ = 16. Antippen mit dem Stift oder Klicken fügt es als Text ein.\nGelesen werden Ziffern, + − · : /, Klammern, Hochzahlen, Brüche und x, y, a, b."))
                                .changed()
                            {
                                state.math.set_enabled(math);
                                actions.push(UiAction::SetMathAssist(math));
                            }
                            if let Some(curve) = pressure_curve_editor(ui, state) {
                                actions.push(UiAction::SavePressureCurve(curve));
                            }
@@ -77,6 +77,41 @@ impl<T> EventLoopBuilderExtAndroid for EventLoopBuilder<T> {
 /// depending on the `android_activity` crate, and instead consume the API that
 /// is re-exported by Winit.
 ///
 /// ink-notes patch: what a pen sample reports (Issue #44).
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum PenAction {
    /// Pen comes near the screen, moves above it or leaves it
    HoverEnter,
    HoverMove,
    HoverExit,
    /// Pen touches the screen, moves on it, is lifted or the gesture is cancelled
    Down,
    Move,
    Up,
    Cancel,
 }
 /// ink-notes patch: one sample of a pen (tool type stylus or eraser). Such pointers are not
 /// reported as `WindowEvent::Touch`; the app collects them with [`take_pen_samples`].
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct PenSample {
    pub action: PenAction,
    /// Position in physical pixels
    pub x: f32,
    pub y: f32,
    /// Usually 0..=1
    pub pressure: f32,
    /// Eraser end of the pen (tool type eraser)
    pub eraser: bool,
    /// `MotionEvent.getButtonState()`; the pen buttons are 0x20 (primary) and 0x40 (secondary)
    pub buttons: u32,
 }
 /// ink-notes patch: the pen samples received since the last call, oldest first.
 pub fn take_pen_samples() -> Vec<PenSample> {
    crate::platform_impl::take_pen_samples()
 }
 /// For compatibility applications should then import the `AndroidApp` type for
 /// their `android_main(app: AndroidApp)` function like:
 /// ```rust
@@ -11,7 +11,7 @@ use std::{
    time::{Duration, Instant},
 };
-use android_activity::input::{InputEvent, KeyAction, Keycode, MotionAction};
+use android_activity::input::{InputEvent, KeyAction, Keycode, MotionAction, ToolType};
 use android_activity::{
    AndroidApp, AndroidAppWaker, ConfigurationRef, InputStatus, MainEvent, Rect,
 };
@@ -382,6 +382,7 @@ impl<T: 'static> EventLoop<T> {
            InputEvent::MotionEvent(motion_event) => {
                let window_id = window::WindowId(WindowId);
                let device_id = event::DeviceId(DeviceId(motion_event.device_id()));
                record_pen_samples(motion_event);
                let phase = match motion_event.action() {
                    MotionAction::Down | MotionAction::PointerDown => {
@@ -408,6 +409,10 @@ impl<T: 'static> EventLoop<T> {
                        };
                    for pointer in pointers {
                        // ink-notes patch: pens are reported through `take_pen_samples`
                        if is_pen(&pointer) {
                            continue;
                        }
                        let location = PhysicalPosition {
                            x: pointer.x() as _,
                            y: pointer.y() as _,
@@ -450,6 +455,15 @@ impl<T: 'static> EventLoop<T> {
                            &mut self.combining_accent,
                        );
                        // ink-notes patch: the character typed, so that text fields receive it
                        let text = match (state, &key_char) {
                            (
                                event::ElementState::Pressed,
                                Some(android_activity::input::KeyMapChar::Unicode(c)),
                            ) if !c.is_control() => Some(smol_str::SmolStr::from_iter([*c])),
                            _ => None,
                        };
                        let event = event::Event::WindowEvent {
                            window_id: window::WindowId(WindowId),
                            event: event::WindowEvent::KeyboardInput {
@@ -460,7 +474,7 @@ impl<T: 'static> EventLoop<T> {
                                    logical_key: keycodes::to_logical(key_char, keycode),
                                    location: keycodes::to_location(keycode),
                                    repeat: key.repeat_count() > 0,
-                                    text: None,
+                                    text,
                                    platform_specific: KeyEventExtra {},
                                },
                                is_synthetic: false,
@@ -1124,3 +1138,55 @@ impl VideoMode {
        self.monitor.clone()
    }
 }
 /// ink-notes patch: pen samples waiting for `take_pen_samples` (Issue #44)
 static PEN_SAMPLES: Mutex<Vec<crate::platform::android::PenSample>> = Mutex::new(Vec::new());
 fn is_pen(pointer: &android_activity::input::Pointer<'_>) -> bool {
    matches!(pointer.tool_type(), ToolType::Stylus | ToolType::Eraser)
 }
 fn record_pen_samples(motion_event: &android_activity::input::MotionEvent<'_>) {
    use crate::platform::android::{PenAction, PenSample};
    let action = match motion_event.action() {
        MotionAction::Down | MotionAction::PointerDown => PenAction::Down,
        MotionAction::Up | MotionAction::PointerUp => PenAction::Up,
        MotionAction::Move => PenAction::Move,
        MotionAction::Cancel => PenAction::Cancel,
        MotionAction::HoverEnter => PenAction::HoverEnter,
        MotionAction::HoverMove => PenAction::HoverMove,
        MotionAction::HoverExit => PenAction::HoverExit,
        _ => return,
    };
    let buttons = motion_event.button_state().0;
    let mut record = |pointer: android_activity::input::Pointer<'_>| {
        if !is_pen(&pointer) {
            return;
        }
        let sample = PenSample {
            action,
            x: pointer.x(),
            y: pointer.y(),
            pressure: pointer.pressure(),
            eraser: pointer.tool_type() == ToolType::Eraser,
            buttons,
        };
        let mut samples = PEN_SAMPLES.lock().unwrap_or_else(|e| e.into_inner());
        // Nobody collects them (app without pen support): don't grow without bound
        if samples.len() >= 4096 {
            samples.remove(0);
        }
        samples.push(sample);
    };
    match action {
        PenAction::Down | PenAction::Up => {
            record(motion_event.pointer_at_index(motion_event.pointer_index()))
        }
        _ => motion_event.pointers().for_each(record),
    }
 }
 pub fn take_pen_samples() -> Vec<crate::platform::android::PenSample> {
    std::mem::take(&mut *PEN_SAMPLES.lock().unwrap_or_else(|e| e.into_inner()))
 }
Author	SHA1	Message	Date
haraldandClaude Opus 5.5	2a9a67d399	chore(release): bump version to 0.41.0 Build & Publish Release / Android APK (push) Successful in 6m23s Details Build & Publish Release / Build Packages & Publish to Gitea (push) In progress Details Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-28 14:48:54 +01:00
haraldandClaude Opus 5.5	307c803246	feat(math): offer the result next to a handwritten = (Issue #46 , stage 3) New module math_assist.rs: when the last two strokes form an = and the pen rests for 500 ms, the strokes left of it (in a band around the =, up to a wide gap) are recognized and computed. The suggestion appears next to the = and shows what was read, e.g. "2⁴ = 16"; tapping it with the pen or clicking inserts the result as a text box in the ink color and as high as the handwriting, as one undo step. The chip is not interactive for egui, so fingers and palms pass through. Any new stroke drops it. In a chain like x = 2 · 3 = the part after the previous = is computed. Off by default: ☰ → Input → "Compute formulas after =", saved in ui.json. math::display writes the recognized expression neatly. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-28 14:45:00 +01:00
haraldandClaude Opus 5.5	d16cd2db72	feat(math): recognize handwritten expressions (Issue #46 , stage 2) New module math_ink.rs turns the strokes of an expression into text for math::solve. Consecutive overlapping strokes are grouped into symbols, each symbol is classified with the $P point-cloud recognizer (plus the turning angle and a small stroke-count penalty) against built-in templates for digits, + ( ) / x y a b, and the structure comes from the positions: stacked lines are =, stacked dots :, lines with symbols above and below are fraction bars, low dots between digits decimal commas and raised symbols exponents. Own templates can be added for stage 4. Tested with synthetic handwriting (slanted, rotated, warped); not used by the UI yet. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-28 14:27:25 +01:00
haraldandClaude Opus 5.5	cd490dd9a7	feat(math): exact evaluation of handwritten expressions (Issue #46 , stage 1) New module math.rs: solve() reads a recognised expression such as 2^4, 2,5 · 3 or (x + 3)² and returns its result as text (16, 7,5, x² + 6x + 9). Own parser with exact fractions and polynomial expansion instead of evalexpr, as implicit multiplication and expanding need it anyway. Not used by the UI yet. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-28 12:34:32 +01:00
haraldandClaude Opus 5.5	8af10fe542	chore(release): bump version to 0.40.0 Build & Publish Release / Android APK (push) Successful in 6m46s Details Build & Publish Release / Build Packages & Publish to Gitea (push) Successful in 12m5s Details Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-28 08:32:30 +01:00
haraldandClaude Opus 5.5	6694d79f16	ci(android): ship the APK with every release (Issue #45 ) The release job now waits for the android job, takes its APK, lists it in SHA256SUMS.txt and uploads it as a release asset. The android job is no longer optional. README describes installing the APK. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-28 08:32:30 +01:00
haraldandClaude Opus 5.5	ad1dab9161	chore: ignore Android keystores Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-28 08:27:52 +01:00
harald	8c436fb28c	docs: update banners with Windows, Android and new import features	2026-10-27 21:45:29 +01:00
haraldandClaude Opus 5.5	7584827c04	ci(android): containerized APK build and CI job (Issue #45 ) - scripts/setup-android-sdk.sh installs fixed versions of the Android command-line tools (checksum verified), platform 34, build-tools 34.0.0 and NDK 28.2 - packaging/android/Containerfile + scripts/build-apk-container.sh build the APK in a container (podman or docker) with JDK 17 and Rust 1.99 - New CI job "Android APK (experimental)": builds the APK and keeps it as a workflow artifact, signed with the key from the secrets ANDROID_KEYSTORE_B64/ANDROID_KEYSTORE_PASS/ANDROID_KEY_ALIAS if set. Not part of the release yet; its failure doesn't block the release. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-27 21:39:35 +01:00
haraldandClaude Opus 5.5	0be321837c	feat(android): Java activity for keyboard text and the system file dialog (Issue #42 ) InkActivity extends NativeActivity: - An invisible view with its own input connection receives the soft keyboard's text (commitText, deleteSurroundingText), so characters without a key event (umlauts by long press, ...) arrive as well. The field is a visible-password field, so keyboards commit each character instead of composing words. - Import and "insert image" open the system file dialog (ACTION_OPEN_DOCUMENT); the chosen file is copied to the cache folder and handed to Rust by path. src/android_bridge.rs calls the activity through JNI and receives its native calls; package-android.sh compiles the class with javac and d8. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-27 21:23:52 +01:00
haraldandClaude Opus 5.5	a8aef30db7	feat(android): pen input, soft keyboard and exports to Downloads (Issues #42 , #44 ) - Pen vs. finger (#44): the patched winit hands Android pointers with tool type stylus/eraser to the app separately (take_pen_samples, with hover and button state) instead of as touch events. src/pen.rs turns them, like octotablet's events on the desktop, into one PenInput stream, so pen buttons, the eraser end and palm rejection work the same everywhere. Hover exit right before touch-down does not count as leaving; a pen without hover leaves 150 ms after lifting. - Soft keyboard: shown via AndroidApp::show_soft_input when a text field gets focus, hidden when it loses it. The patched winit now fills KeyEvent::text, so typed characters reach egui. - Exports (PDF, PNG, SVG) are written to the app folder and copied to Download/ink-notes through the MediaStore (Android 10+, via JNI). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-27 20:54:48 +01:00