onyxsdk_pen

This plugin integrates the Onyx Pen SDK into Flutter to improve e-ink performance in drawing apps.

Most of the SDK functionality is omitted due to it being restricted to Onyx devices. We instead only provide the OnyxSdkPenArea widget. The children of this widget (typically including a CustomPaint and GestureDetector) will automatically gain fluid pen strokes.

You are responsible for taking user input and drawing it. The OnyxSdkPenArea widget will just make things faster on Onyx devices.

When used on devices that aren't Onyx Android devices, the OnyxSdkPenArea widget will just return its child.

SDK status

If you use this SDK, you may have difficulty publishing your app to Google Play.

The SDK currently doesn't support 16KB page sizes, but support is required by Google Play as of November 1st 2025.

The only solution is waiting for an SDK update from Onyx that supports 16KB page sizes. Please see onyx-intl#132 for more information.

Getting Started

Android

See this commit for an example of the following setup...

android/app/build.gradle

android {
    defaultConfig {
        // Onyx SDK requires 23 or higher
        minSdkVersion 23
    }

    packagingOptions {
        pickFirst 'lib/*/libc++_shared.so'
        pickFirst 'androidsupportmultidexversion.txt'
    }
}

android/app/src/main/AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.adilhanney.saber">

    <!-- Add this `tools:replace` attribute to the `application` tag -->
    <application
        tools:replace="android:label">

    </application>
</manifest>

In my case, I got a compiler error saying that I needed tools:replace="android:allowBackup" so I merged the two with tools:replace="android:label,android:allowBackup".

android/build.gradle

allprojects {
    repositories {
        google()
        mavenCentral()

        // Add these two lines
        maven {
            url "https://jitpack.io"
        }
        maven {
            url "http://repo.boox.com/repository/maven-public/"
            allowInsecureProtocol true
        }
    }
}

pubspec.yaml

dependencies:
  onyxsdk_pen: ^1.0.3

lib/main.dart

// Wrap your drawable widget with the OnyxSdkPenArea widget, e.g.
OnyxSdkPenArea(
  // Optional parameters:
  strokeStyle: OnyxStrokeStyle.fountainPen,
  strokeColor: Colors.black,
  strokeWidth: 3.0,

  child: GestureDetector(
    onPanUpdate: (details) {},
    child: CustomPaint(
      painter: MyPainter(points),
    ),
  ),
),

You can optionally run the init method in the main function of your app to initialize the Onyx SDK. This is not required, but it will improve initial performance on non-Onyx Android devices.

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await OnyxSdkPenArea.init();
  runApp(MyApp());
}

Help wanted

I no longer have an Onyx device, so I can't really develop this plugin any further. If you are able to, we're looking for help with this feature: https://github.com/saber-notes/saber/issues/848

Libraries

onyxsdk_pen