react-native-vision-camera/docs/docs/guides/FRAME_PROCESSOR_CREATE_PLUGIN_ANDROID.mdx

---
id: frame-processors-plugins-android
title: Creating Frame Processor Plugins
sidebar_label: Creating Frame Processor Plugins (Android)
---

import Tabs from '@theme/Tabs'
import TabItem from '@theme/TabItem'

## Creating a Frame Processor Plugin for Android

The Frame Processor Plugin API is built to be as extensible as possible, which allows you to create custom Frame Processor Plugins.
In this guide we will create a custom Face Detector Plugin which can be used from JS.

Android Frame Processor Plugins can be written in either **Java**, **Kotlin** or **C++ (JNI)**.

### Mostly automatic setup

1. Run [Vision Camera Plugin Builder CLI](https://github.com/mateusz1913/vision-camera-plugin-builder)

```sh
npx vision-camera-plugin-builder android
```

:::info
The CLI will ask you for the path to project's Android Manifest file, name of the plugin (e.g. `FaceDetectorFrameProcessorPlugin`), name of the exposed method (e.g. `detectFaces`) and language you want to use for plugin development (Java or Kotlin).
For reference see the [CLI's docs](https://github.com/mateusz1913/vision-camera-plugin-builder#%EF%B8%8F-options).
:::

2. Register the package in MainApplication.java

```java
        @Override
        protected List<ReactPackage> getPackages() {
          @SuppressWarnings("UnnecessaryLocalVariable")
          List<ReactPackage> packages = new PackageList(this).getPackages();
          // ...
          // highlight-next-line
          packages.add(new FaceDetectorFrameProcessorPluginPackage()); // <- add
          return packages;
        }
```

### Manual setup

<Tabs
  defaultValue="java"
  values={[
    {label: 'Java', value: 'java'},
    {label: 'Kotlin', value: 'kotlin'}
  ]}>
<TabItem value="java">

1. Open your Project in Android Studio
2. Create a Java source file, for the Face Detector Plugin this will be called `FaceDetectorFrameProcessorPlugin.java`.
3. Add the following code:

```java
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import com.mrousavy.camera.frameprocessor.Frame;
import com.mrousavy.camera.frameprocessor.FrameProcessorPlugin;

public class FaceDetectorFrameProcessorPlugin extends FrameProcessorPlugin {
  FaceDetectorFrameProcessorPlugin(@Nullable Map<String, Object> options) {}

  @Nullable
  @Override
  public Object callback(@NonNull Frame frame, @Nullable Map<String, Object> arguments) {
// highlight-next-line
    // code goes here
    return null;
  }
}
```

4. **Implement your Frame Processing.** See the [Example Plugin (Java)](https://github.com/mrousavy/react-native-vision-camera/blob/main/package/example/android/app/src/main/java/com/mrousavy/camera/example/ExampleFrameProcessorPlugin.java) for reference.
5. Create a new Java file which registers the Frame Processor Plugin in a React Package, for the Face Detector plugin this file will be called `FaceDetectorFrameProcessorPluginPackage.java`:

```java
import androidx.annotation.NonNull;
import com.facebook.react.ReactPackage;
import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.uimanager.ViewManager;
import com.mrousavy.camera.frameprocessor.FrameProcessorPlugin;
import com.mrousavy.camera.frameprocessor.FrameProcessorPluginRegistry;

public class FaceDetectorFrameProcessorPluginPackage implements ReactPackage {
  // highlight-start
  FaceDetectorFrameProcessorPluginPackage() {
    FrameProcessorPluginRegistry.addFrameProcessorPlugin("detectFaces", options -> new FaceDetectorFrameProcessorPlugin(options));
  }
  // highlight-end

  @NonNull
  @Override
  public List<NativeModule> createNativeModules(@NonNull ReactApplicationContext reactContext) {
    return Collections.emptyList();
  }

  @NonNull
  @Override
  public List<ViewManager> createViewManagers(@NonNull ReactApplicationContext reactContext) {
    return Collections.emptyList();
  }
}
```

:::note
The Frame Processor Plugin will be exposed to JS through the `VisionCameraProxy` object. In this case, it would be `VisionCameraProxy.getFrameProcessorPlugin("detectFaces")`.
:::

6. Register the package in MainApplication.java

```java
        @Override
        protected List<ReactPackage> getPackages() {
          @SuppressWarnings("UnnecessaryLocalVariable")
          List<ReactPackage> packages = new PackageList(this).getPackages();
          // ...
          // highlight-next-line
          packages.add(new FaceDetectorFrameProcessorPluginPackage()); // <- add
          return packages;
        }
```

</TabItem>
<TabItem value="kotlin">

1. Open your Project in Android Studio
2. Create a Kotlin source file, for the Face Detector Plugin this will be called `FaceDetectorFrameProcessorPlugin.kt`.
3. Add the following code:

```kotlin
import com.mrousavy.camera.frameprocessor.Frame
import com.mrousavy.camera.frameprocessor.FrameProcessorPlugin

class FaceDetectorFrameProcessorPlugin(options: Map<String, Any>?): FrameProcessorPlugin(options) {

  override fun callback(frame: Frame, arguments: Map<String, Any>?): Any? {
// highlight-next-line
    // code goes here
    return null
  }
}
```

4. **Implement your Frame Processing.** See the [Example Plugin (Java)](https://github.com/mrousavy/react-native-vision-camera/blob/main/package/example/android/app/src/main/java/com/mrousavy/camera/example/ExampleFrameProcessorPlugin.java) for reference.
5. Create a new Kotlin file which registers the Frame Processor Plugin in a React Package, for the Face Detector plugin this file will be called `FaceDetectorFrameProcessorPluginPackage.kt`:

```kotlin
import com.facebook.react.ReactPackage
import com.facebook.react.bridge.NativeModule
import com.facebook.react.bridge.ReactApplicationContext
import com.facebook.react.uimanager.ViewManager
import com.mrousavy.camera.frameprocessor.FrameProcessorPlugin

class FaceDetectorFrameProcessorPluginPackage : ReactPackage {
  // highlight-start
  init {
    FrameProcessorPluginRegistry.addFrameProcessorPlugin("detectFaces") { options ->
      FaceDetectorFrameProcessorPlugin(options)
    }
  }
  // highlight-end

  override fun createNativeModules(reactContext: ReactApplicationContext): List<NativeModule> {
    return emptyList()
  }

  override fun createViewManagers(reactContext: ReactApplicationContext): List<ViewManager<*, *>> {
    return emptyList()
  }
}
```

:::note
The Frame Processor Plugin will be exposed to JS through the `VisionCameraProxy` object. In this case, it would be `VisionCameraProxy.getFrameProcessorPlugin("detectFaces")`.
:::

6. Register the package in MainApplication.java

```java
        @Override
        protected List<ReactPackage> getPackages() {
          @SuppressWarnings("UnnecessaryLocalVariable")
          List<ReactPackage> packages = new PackageList(this).getPackages();
          // ...
          // highlight-next-line
          packages.add(new FaceDetectorFrameProcessorPluginPackage()); // <- add
          return packages;
        }
```

</TabItem>
</Tabs>

<br />

#### 🚀 Next section: [Finish creating your Frame Processor Plugin](frame-processors-plugins-final) (or [add iOS support to your Frame Processor Plugin](frame-processors-plugins-ios))