[camera] Simplest camera plugin migration

packages/camera/android/src/main/java/dev/flutter/plugins/camera/CameraPlugin.java

@@ -0,0 +1,103 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dev.flutter.plugins.camera;
+
+import android.hardware.camera2.CameraAccessException;
+import android.os.Build;
+
+import androidx.annotation.NonNull;
+
+import io.flutter.embedding.engine.plugins.FlutterPlugin;
+import io.flutter.embedding.engine.plugins.activity.ActivityAware;
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
+import io.flutter.plugin.common.EventChannel;
+import io.flutter.plugin.common.MethodCall;
+import io.flutter.plugin.common.MethodChannel;
+import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
+import io.flutter.plugin.common.MethodChannel.Result;
+import io.flutter.plugin.common.PluginRegistry;
+import io.flutter.plugins.camera.Camera;
+import io.flutter.plugins.camera.CameraChannelHandler;
+import io.flutter.plugins.camera.CameraPermissions;
+import io.flutter.plugins.camera.CameraUtils;
+
+public class CameraPlugin implements FlutterPlugin, ActivityAware {
+
+  private FlutterPluginBinding pluginBinding;
+  private ActivityPluginBinding activityBinding;
+
+  private final CameraPermissions cameraPermissions = new CameraPermissions();
+  private EventChannel imageStreamChannel;
+  private Camera camera;
+
+  @Override
+  public void onAttachedToEngine(FlutterPluginBinding flutterPluginBinding) {
+    this.pluginBinding = flutterPluginBinding;
+    this.imageStreamChannel = new EventChannel(
+        this.pluginBinding.getFlutterEngine().getDartExecutor(),
+        "plugins.flutter.io/camera/imageStream"
+    );
+  }
+
+  @Override
+  public void onDetachedFromEngine(FlutterPluginBinding flutterPluginBinding) {
+    this.pluginBinding = null;
+  }
+
+  @Override
+  public void onAttachedToActivity(ActivityPluginBinding activityPluginBinding) {
+    // Setup
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
+      // When a background flutter view tries to register the plugin, the registrar has no activity.
+      // We stop the registration process as this plugin is foreground only. Also, if the sdk is
+      // less than 21 (min sdk for Camera2) we don't register the plugin.
+      return;
+    }
+
+    this.activityBinding = activityPluginBinding;
+
+    final MethodChannel channel =
+        new MethodChannel(pluginBinding.getFlutterEngine().getDartExecutor(), "plugins.flutter.io/camera");
+
+    channel.setMethodCallHandler(new CameraChannelHandler(
+        activityPluginBinding.getActivity(),
+        pluginBinding.getFlutterEngine().getRenderer(),
+        pluginBinding.getFlutterEngine().getDartExecutor(),
+        new EventChannel(pluginBinding.getFlutterEngine().getDartExecutor(), "plugins.flutter.io/camera/imageStream"),
+        new NewEmbeddingPermissions(activityPluginBinding)
+    ));
+  }
+
+  @Override
+  public void onDetachedFromActivityForConfigChanges() {
+    // Ignore
+  }
+
+  @Override
+  public void onReattachedToActivityForConfigChanges(ActivityPluginBinding activityPluginBinding) {
+    // Ignore
+  }
+
+  @Override
+  public void onDetachedFromActivity() {
+    // Teardown
+    this.activityBinding = null;
+  }
+
+  private static class NewEmbeddingPermissions implements CameraPermissions.Permissions {
+    private ActivityPluginBinding activityPluginBinding;
+
+    private NewEmbeddingPermissions(@NonNull ActivityPluginBinding activityPluginBinding) {
+      this.activityPluginBinding = activityPluginBinding;
+    }
+
+    @Override
+    public PluginRegistry.Registrar addRequestPermissionsResultListener(PluginRegistry.RequestPermissionsResultListener listener) {
+      activityPluginBinding.addRequestPermissionsResultListener(listener);
+
+      return null; // <- this is a breaking change.
+    }
+  }
+}

packages/camera/android/src/main/java/io/flutter/plugins/camera/Camera.java

@@ -29,6 +29,7 @@
 import io.flutter.plugin.common.EventChannel;
 import io.flutter.plugin.common.MethodChannel.Result;
 import io.flutter.view.FlutterView;
+import io.flutter.view.TextureRegistry;
 import io.flutter.view.TextureRegistry.SurfaceTextureEntry;
 import java.io.File;
 import java.io.FileOutputStream;
@@ -74,7 +75,7 @@ public enum ResolutionPreset {
 
   public Camera(
       final Activity activity,
-      final FlutterView flutterView,
+      final TextureRegistry textureRegistry,
       final String cameraName,
       final String resolutionPreset,
       final boolean enableAudio)
@@ -85,7 +86,7 @@ public Camera(
 
     this.cameraName = cameraName;
     this.enableAudio = enableAudio;
-    this.flutterTexture = flutterView.createSurfaceTexture();
+    this.flutterTexture = textureRegistry.createSurfaceTexture();
     this.cameraManager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
     orientationEventListener =
         new OrientationEventListener(activity.getApplicationContext()) {
@@ -233,7 +234,7 @@ private void writeToFile(ByteBuffer buffer, File file) throws IOException {
     }
   }
 
-  SurfaceTextureEntry getFlutterTexture() {
+  public SurfaceTextureEntry getFlutterTexture() {
     return flutterTexture;
   }
 

packages/camera/android/src/main/java/io/flutter/plugins/camera/CameraChannelHandler.java

@@ -0,0 +1,163 @@
+package io.flutter.plugins.camera;
+
+import android.app.Activity;
+import android.hardware.camera2.CameraAccessException;
+
+import androidx.annotation.NonNull;
+
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugin.common.EventChannel;
+import io.flutter.plugin.common.MethodCall;
+import io.flutter.plugin.common.MethodChannel;
+import io.flutter.view.TextureRegistry;
+
+public class CameraChannelHandler implements MethodChannel.MethodCallHandler {
+
+  private final CameraPermissions cameraPermissions = new CameraPermissions();
+  private final Activity activity;
+  private final TextureRegistry textureRegistry;
+  private final BinaryMessenger messenger;
+  private final EventChannel imageStreamChannel;
+  private final CameraPermissions.Permissions permissions;
+  private Camera camera;
+
+  public CameraChannelHandler(
+      @NonNull Activity activity,
+      @NonNull TextureRegistry textureRegistry,
+      @NonNull BinaryMessenger binaryMessenger,
+      @NonNull EventChannel imageStreamChannel,
+      @NonNull CameraPermissions.Permissions permissions
+  ) {
+    this.activity = activity;
+    this.textureRegistry = textureRegistry;
+    this.messenger = binaryMessenger;
+    this.imageStreamChannel = imageStreamChannel;
+    this.permissions = permissions;
+  }
+
+  @Override
+  public void onMethodCall(@NonNull MethodCall call, @NonNull final MethodChannel.Result result) {
+    switch (call.method) {
+      case "availableCameras":
+        try {
+          result.success(CameraUtils.getAvailableCameras(activity));
+        } catch (Exception e) {
+          handleException(e, result);
+        }
+        break;
+      case "initialize":
+      {
+        if (camera != null) {
+          camera.close();
+        }
+        cameraPermissions.requestPermissions(
+            activity,
+            permissions,
+            call.argument("enableAudio"),
+            (String errCode, String errDesc) -> {
+              if (errCode == null) {
+                try {
+                  instantiateCamera(call, result);
+                } catch (Exception e) {
+                  handleException(e, result);
+                }
+              } else {
+                result.error(errCode, errDesc, null);
+              }
+            });
+
+        break;
+      }
+      case "takePicture":
+      {
+        camera.takePicture(call.argument("path"), result);
+        break;
+      }
+      case "prepareForVideoRecording":
+      {
+        // This optimization is not required for Android.
+        result.success(null);
+        break;
+      }
+      case "startVideoRecording":
+      {
+        camera.startVideoRecording(call.argument("filePath"), result);
+        break;
+      }
+      case "stopVideoRecording":
+      {
+        camera.stopVideoRecording(result);
+        break;
+      }
+      case "pauseVideoRecording":
+      {
+        camera.pauseVideoRecording(result);
+        break;
+      }
+      case "resumeVideoRecording":
+      {
+        camera.resumeVideoRecording(result);
+        break;
+      }
+      case "startImageStream":
+      {
+        try {
+          camera.startPreviewWithImageStream(imageStreamChannel);
+          result.success(null);
+        } catch (Exception e) {
+          handleException(e, result);
+        }
+        break;
+      }
+      case "stopImageStream":
+      {
+        try {
+          camera.startPreview();
+          result.success(null);
+        } catch (Exception e) {
+          handleException(e, result);
+        }
+        break;
+      }
+      case "dispose":
+      {
+        if (camera != null) {
+          camera.dispose();
+        }
+        result.success(null);
+        break;
+      }
+      default:
+        result.notImplemented();
+        break;
+    }
+  }
+
+  private void instantiateCamera(MethodCall call, MethodChannel.Result result) throws CameraAccessException {
+    String cameraName = call.argument("cameraName");
+    String resolutionPreset = call.argument("resolutionPreset");
+    boolean enableAudio = call.argument("enableAudio");
+    camera = new Camera(activity, textureRegistry, cameraName, resolutionPreset, enableAudio);
+
+    EventChannel cameraEventChannel =
+        new EventChannel(
+            messenger,
+            "flutter.io/cameraPlugin/cameraEvents" + camera.getFlutterTexture().id());
+    camera.setupCameraEventChannel(cameraEventChannel);
+
+    camera.open(result);
+  }
+
+  // We move catching CameraAccessException out of onMethodCall because it causes a crash
+  // on plugin registration for sdks incompatible with Camera2 (< 21). We want this plugin to
+  // to be able to compile with <21 sdks for apps that want the camera and support earlier version.
+  @SuppressWarnings("ConstantConditions")
+  private void handleException(Exception exception, MethodChannel.Result result) {
+    if (exception instanceof CameraAccessException) {
+      result.error("CameraAccess", exception.getMessage(), null);
+    }
+
+    throw (RuntimeException) exception;
+  }
+}

packages/camera/android/src/main/java/io/flutter/plugins/camera/CameraPermissions.java

@@ -6,6 +6,8 @@
 import android.content.pm.PackageManager;
 import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
+
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
 import io.flutter.plugin.common.PluginRegistry;
 import io.flutter.plugin.common.PluginRegistry.Registrar;
 
@@ -14,13 +16,12 @@ public class CameraPermissions {
   private boolean ongoing = false;
 
   public void requestPermissions(
-      Registrar registrar, boolean enableAudio, ResultCallback callback) {
+      Activity activity, Permissions permissions, boolean enableAudio, ResultCallback callback) {
     if (ongoing) {
       callback.onResult("cameraPermission", "Camera permission request ongoing");
     }
-    Activity activity = registrar.activity();
     if (!hasCameraPermission(activity) || (enableAudio && !hasAudioPermission(activity))) {
-      registrar.addRequestPermissionsResultListener(
+      permissions.addRequestPermissionsResultListener(
           new CameraRequestPermissionsListener(
               (String errorCode, String errorDescription) -> {
                 ongoing = false;
@@ -74,7 +75,13 @@ public boolean onRequestPermissionsResult(int id, String[] permissions, int[] gr
     }
   }
 
-  interface ResultCallback {
+  public interface Permissions {
+    Registrar addRequestPermissionsResultListener(
+        PluginRegistry.RequestPermissionsResultListener listener
+    );
+  }
+
+  public interface ResultCallback {
     void onResult(String errorCode, String errorDescription);
   }
 }