Sample Implementations

Three open-source applications demonstrate real-world Onyx SDK inking integration at varying levels of complexity. Each is a useful reference for specific aspects of the API.

Project

Language

SDK version

Best reference for

OnyxAndroidDemo

Java

pen 1.2.1

Official minimal examples of every SDK feature

PngNote

Kotlin + Compose

pen 1.2.1

SurfaceView canvas, eraser throttling, Compose + SDK integration

notable

Kotlin

pen 1.5.2

Full production app, latest SDK, NeoTools pen styles

OnyxAndroidDemo

https://github.com/onyx-intl/OnyxAndroidDemo

The official sample repository from Onyx International. Demonstrates every major SDK feature in isolated, minimal Java activities.

Maintainer

Onyx International (official)

Language

Java

SDK versions

onyxsdk-pen:1.2.1, onyxsdk-device:1.1.11

Stars / forks

211 / 45

Status

Infrequently updated; SDK versions are old but patterns are stable

Key demo activities

Activity

What it shows

ScribbleTouchHelperDemoActivity

TouchHelper on a SurfaceView. Minimal end-to-end setup: create → setLimitRect → openRawDrawing → callbacks. The canonical “hello world” for the pen SDK.

ScribbleWebViewDemoActivity

Overlaying ink capture on a WebView — useful for PDF annotation or web-content inking.

ScribbleMoveEraserDemoActivity

Eraser tool implementation using the eraser callbacks in RawInputCallback.

ScribbleMultipleScribbleViewActivity

Multiple independent drawing regions in a single Activity, showing setMultiRegionMode() or separate TouchHelper instances per view.

Notes for SDK 1.4+ users

The demo uses SDK 1.2.1, which differs from the current recommended version in two important ways:

  • TouchPoint is at com.onyx.android.sdk.pen.data.TouchPoint (moved to com.onyx.android.sdk.data.note.TouchPoint in 1.4.x).

  • ReflectUtil crashes fatally if VMRuntime.setHiddenApiExemptions is absent from the ROM. The hidden-API bypass (see Hidden-API bypass) is not shown in the demo — add it before adopting these patterns on Android 13+.

PngNote

https://github.com/karino2/PngNote

A minimal Kotlin note-taking app that stores pages as plain PNG files. The drawing engine in CanvasBoox.kt is one of the clearest available examples of TouchHelper used with a SurfaceView and a real bitmap canvas.

Maintainer

karino2 (independent)

Language

Kotlin, Jetpack Compose UI

SDK versions

onyxsdk-pen:1.2.1 (referenced; may be vendored)

Stars / forks

70 / 11

Supported devices

BOOX Note3, Note2, Note Air, Nova2. Not compatible with Poke series.

Status

Last release September 2021 (v0.4). Stable but unmaintained.

License

MIT

What to study in this repo

ui/CanvasBoox.kt — the entire inking implementation in one file:

  • Lazy ``TouchHelper`` init — private val touchHelper by lazy { TouchHelper.create(this, inputCallback) }

  • Stroke style setup — setStrokeWidth, setStrokeColor, setStrokeStyle(TouchHelper.STROKE_STYLE_PENCIL) called before openRawDrawing().

  • Eraser with throttle — onRawErasingTouchPointMoveReceived accumulates points and refreshes every 300 ms or 100 points, avoiding excessive EPD updates during erasing.

  • Jump-point filter — skips points where abs(prev.y - point.y) >= 30 to suppress digitizer noise during fast strokes.

  • ``EpdController.enablePost(view, 1)`` called during eraser init to enable partial-update post-processing.

  • SurfaceView lifecycle — surfaceDestroyed calls closeRawDrawing(); onRestart reattaches the surface callback and resumes drawing.

  • Quadratic curve rendering — touch points drawn as quadTo paths on a bitmap, giving smooth curves between sampled points.

notable

https://github.com/Ethran/notable

A maintained, production-quality note-taking app for Onyx BOOX devices. Active fork of the archived olup/notable. Uses the latest SDK version of the three samples listed here and demonstrates NeoTools pen styles.

Maintainer

Ethran (community-maintained fork)

Language

Kotlin

SDK versions

onyxsdk-pen:1.5.2, onyxsdk-base:1.8.4, onyxsdk-device:1.3.3

Stars / forks

194 / 31

Requires

Android 10+ (API 29)

Community

Discord: discord.gg/rvNHgaDmN2

Status

Actively maintained (1 000+ commits)

License

Open source (see repo)

What to study in this repo

  • Latest SDK version — uses pen 1.5.2 / base 1.8.4 / device 1.3.3, the most recent versions available at time of writing. Useful to see what changed from 1.4.x.

  • NeoTools pen styles — integrates NeoBallpointPen, NeoFountainPen, etc. Note that NeoCharcoalPenV2, NeoMarkerPen, and NeoBrushPen are disabled by default due to instability on some devices.

  • PDF annotation — full PDF reading with ink overlay, making it the closest open-source analogue to this project’s own use case.

  • Performance patterns — fast page turns with bitmap caching, infinite vertical scroll, gesture controls. The codebase shows how to manage TouchHelper lifecycle across page/scroll events.

  • Database stroke encoding — strokes persisted to SQLite (Documents/notabledb); the schema is documented in docs/database-structure.md in the repo.

Stability note on NeoTools

The following pen types are present in the SDK but disabled in notable due to crash risk on certain devices. Treat them as experimental:

  • NeoCharcoalPenV2

  • NeoMarkerPen

  • NeoBrushPen