[camera] Re-land Add ProcessCameraProvider class to CameraX Plugin

packages/camera/camera_android_camerax/CHANGELOG.md

@@ -3,3 +3,4 @@
 * Creates camera_android_camerax plugin for development.
 * Adds CameraInfo class and removes unnecessary code from plugin.
 * Adds CameraSelector class.
+* Adds ProcessCameraProvider class.

packages/camera/camera_android_camerax/android/build.gradle

@@ -36,16 +36,6 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-dependencies {
-    // CameraX core library using the camera2 implementation must use same version number.
-    def camerax_version = "1.2.0-beta01"
-    implementation "androidx.camera:camera-core:${camerax_version}"
-    implementation "androidx.camera:camera-camera2:${camerax_version}"
-    implementation "androidx.camera:camera-lifecycle:${camerax_version}"
-    testImplementation 'junit:junit:4.13.2'
-    testImplementation 'org.mockito:mockito-inline:4.7.0'
-    testImplementation 'androidx.test:core:1.4.0'
-}
     testOptions {
         unitTests.includeAndroidResources = true
         unitTests.returnDefaultValues = true
@@ -58,3 +48,16 @@ dependencies {
         }
     }
 }
+
+dependencies {
+    // CameraX core library using the camera2 implementation must use same version number.
+    def camerax_version = "1.2.0-beta02"
+    implementation "androidx.camera:camera-core:${camerax_version}"
+    implementation "androidx.camera:camera-camera2:${camerax_version}"
+    implementation "androidx.camera:camera-lifecycle:${camerax_version}"
+    implementation 'com.google.guava:guava:31.1-android'
+    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.mockito:mockito-inline:4.7.0'
+    testImplementation 'androidx.test:core:1.4.0'
+    testImplementation 'org.robolectric:robolectric:4.8'
+}

packages/camera/camera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/CameraAndroidCameraxPlugin.java

@@ -15,6 +15,7 @@
 public final class CameraAndroidCameraxPlugin implements FlutterPlugin, ActivityAware {
   private InstanceManager instanceManager;
   private FlutterPluginBinding pluginBinding;
+  private ProcessCameraProviderHostApiImpl processCameraProviderHostApi;
 
   /**
    * Initialize this within the {@code #configureFlutterEngine} of a Flutter activity or fragment.
@@ -39,6 +40,10 @@ void setUp(BinaryMessenger binaryMessenger, Context context) {
         binaryMessenger, new JavaObjectHostApiImpl(instanceManager));
     GeneratedCameraXLibrary.CameraSelectorHostApi.setup(
         binaryMessenger, new CameraSelectorHostApiImpl(binaryMessenger, instanceManager));
+    processCameraProviderHostApi =
+        new ProcessCameraProviderHostApiImpl(binaryMessenger, instanceManager, context);
+    GeneratedCameraXLibrary.ProcessCameraProviderHostApi.setup(
+        binaryMessenger, processCameraProviderHostApi);
   }
 
   @Override
@@ -60,15 +65,33 @@ public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
   // Activity Lifecycle methods:
 
   @Override
-  public void onAttachedToActivity(@NonNull ActivityPluginBinding activityPluginBinding) {}
+  public void onAttachedToActivity(@NonNull ActivityPluginBinding activityPluginBinding) {
+    updateContext(activityPluginBinding.getActivity());
+  }
 
   @Override
-  public void onDetachedFromActivityForConfigChanges() {}
+  public void onDetachedFromActivityForConfigChanges() {
+    updateContext(pluginBinding.getApplicationContext());
+  }
 
   @Override
   public void onReattachedToActivityForConfigChanges(
-      @NonNull ActivityPluginBinding activityPluginBinding) {}
+      @NonNull ActivityPluginBinding activityPluginBinding) {
+    updateContext(activityPluginBinding.getActivity());
+  }
 
   @Override
-  public void onDetachedFromActivity() {}
+  public void onDetachedFromActivity() {
+    updateContext(pluginBinding.getApplicationContext());
+  }
+
+  /**
+   * Updates context that is used to fetch the corresponding instance of a {@code
+   * ProcessCameraProvider}.
+   */
+  private void updateContext(Context context) {
+    if (processCameraProviderHostApi != null) {
+      processCameraProviderHostApi.setContext(context);
+    }
+  }
 }

packages/camera/camera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/CameraInfoFlutterApiImpl.java

@@ -18,7 +18,6 @@ public CameraInfoFlutterApiImpl(
   }
 
   void create(CameraInfo cameraInfo, Reply<Void> reply) {
-    instanceManager.addHostCreatedInstance(cameraInfo);
-    create(instanceManager.getIdentifierForStrongReference(cameraInfo), reply);
+    create(instanceManager.addHostCreatedInstance(cameraInfo), reply);
   }
 }

packages/camera/camera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/GeneratedCameraXLibrary.java

@@ -22,6 +22,13 @@
 /** Generated class from Pigeon. */
 @SuppressWarnings({"unused", "unchecked", "CodeBlock2Expr", "RedundantSuppression"})
 public class GeneratedCameraXLibrary {
+
+  public interface Result<T> {
+    void success(T result);
+
+    void error(Throwable error);
+  }
+
   private static class JavaObjectHostApiCodec extends StandardMessageCodec {
     public static final JavaObjectHostApiCodec INSTANCE = new JavaObjectHostApiCodec();
 
@@ -311,6 +318,133 @@ public void create(
     }
   }
 
+  private static class ProcessCameraProviderHostApiCodec extends StandardMessageCodec {
+    public static final ProcessCameraProviderHostApiCodec INSTANCE =
+        new ProcessCameraProviderHostApiCodec();
+
+    private ProcessCameraProviderHostApiCodec() {}
+  }
+
+  /** Generated interface from Pigeon that represents a handler of messages from Flutter. */
+  public interface ProcessCameraProviderHostApi {
+    void getInstance(Result<Long> result);
+
+    @NonNull
+    List<Long> getAvailableCameraInfos(@NonNull Long identifier);
+
+    /** The codec used by ProcessCameraProviderHostApi. */
+    static MessageCodec<Object> getCodec() {
+      return ProcessCameraProviderHostApiCodec.INSTANCE;
+    }
+
+    /**
+     * Sets up an instance of `ProcessCameraProviderHostApi` to handle messages through the
+     * `binaryMessenger`.
+     */
+    static void setup(BinaryMessenger binaryMessenger, ProcessCameraProviderHostApi api) {
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<>(
+                binaryMessenger,
+                "dev.flutter.pigeon.ProcessCameraProviderHostApi.getInstance",
+                getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+              (message, reply) -> {
+                Map<String, Object> wrapped = new HashMap<>();
+                try {
+                  Result<Long> resultCallback =
+                      new Result<Long>() {
+                        public void success(Long result) {
+                          wrapped.put("result", result);
+                          reply.reply(wrapped);
+                        }
+
+                        public void error(Throwable error) {
+                          wrapped.put("error", wrapError(error));
+                          reply.reply(wrapped);
+                        }
+                      };
+
+                  api.getInstance(resultCallback);
+                } catch (Error | RuntimeException exception) {
+                  wrapped.put("error", wrapError(exception));
+                  reply.reply(wrapped);
+                }
+              });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<>(
+                binaryMessenger,
+                "dev.flutter.pigeon.ProcessCameraProviderHostApi.getAvailableCameraInfos",
+                getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+              (message, reply) -> {
+                Map<String, Object> wrapped = new HashMap<>();
+                try {
+                  ArrayList<Object> args = (ArrayList<Object>) message;
+                  Number identifierArg = (Number) args.get(0);
+                  if (identifierArg == null) {
+                    throw new NullPointerException("identifierArg unexpectedly null.");
+                  }
+                  List<Long> output =
+                      api.getAvailableCameraInfos(
+                          (identifierArg == null) ? null : identifierArg.longValue());
+                  wrapped.put("result", output);
+                } catch (Error | RuntimeException exception) {
+                  wrapped.put("error", wrapError(exception));
+                }
+                reply.reply(wrapped);
+              });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
+    }
+  }
+
+  private static class ProcessCameraProviderFlutterApiCodec extends StandardMessageCodec {
+    public static final ProcessCameraProviderFlutterApiCodec INSTANCE =
+        new ProcessCameraProviderFlutterApiCodec();
+
+    private ProcessCameraProviderFlutterApiCodec() {}
+  }
+
+  /** Generated class from Pigeon that represents Flutter messages that can be called from Java. */
+  public static class ProcessCameraProviderFlutterApi {
+    private final BinaryMessenger binaryMessenger;
+
+    public ProcessCameraProviderFlutterApi(BinaryMessenger argBinaryMessenger) {
+      this.binaryMessenger = argBinaryMessenger;
+    }
+
+    public interface Reply<T> {
+      void reply(T reply);
+    }
+
+    static MessageCodec<Object> getCodec() {
+      return ProcessCameraProviderFlutterApiCodec.INSTANCE;
+    }
+
+    public void create(@NonNull Long identifierArg, Reply<Void> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<>(
+              binaryMessenger,
+              "dev.flutter.pigeon.ProcessCameraProviderFlutterApi.create",
+              getCodec());
+      channel.send(
+          new ArrayList<Object>(Arrays.asList(identifierArg)),
+          channelReply -> {
+            callback.reply(null);
+          });
+    }
+  }
+
   private static Map<String, Object> wrapError(Throwable exception) {
     Map<String, Object> errorMap = new HashMap<>();
     errorMap.put("message", exception.toString());

packages/camera/camera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/ProcessCameraProviderFlutterApiImpl.java

@@ -0,0 +1,23 @@
+// Copyright 2013 The Flutter 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 io.flutter.plugins.camerax;
+
+import androidx.camera.lifecycle.ProcessCameraProvider;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugins.camerax.GeneratedCameraXLibrary.ProcessCameraProviderFlutterApi;
+
+public class ProcessCameraProviderFlutterApiImpl extends ProcessCameraProviderFlutterApi {
+  public ProcessCameraProviderFlutterApiImpl(
+      BinaryMessenger binaryMessenger, InstanceManager instanceManager) {
+    super(binaryMessenger);
+    this.instanceManager = instanceManager;
+  }
+
+  private final InstanceManager instanceManager;
+
+  void create(ProcessCameraProvider processCameraProvider, Reply<Void> reply) {
+    create(instanceManager.addHostCreatedInstance(processCameraProvider), reply);
+  }
+}

packages/camera/camera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/ProcessCameraProviderHostApiImpl.java

@@ -0,0 +1,87 @@
+// Copyright 2013 The Flutter 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 io.flutter.plugins.camerax;
+
+import android.content.Context;
+import androidx.annotation.NonNull;
+import androidx.camera.core.CameraInfo;
+import androidx.camera.lifecycle.ProcessCameraProvider;
+import androidx.core.content.ContextCompat;
+import com.google.common.util.concurrent.ListenableFuture;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugins.camerax.GeneratedCameraXLibrary.ProcessCameraProviderHostApi;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ProcessCameraProviderHostApiImpl implements ProcessCameraProviderHostApi {
+  private final BinaryMessenger binaryMessenger;
+  private final InstanceManager instanceManager;
+
+  private Context context;
+
+  public ProcessCameraProviderHostApiImpl(
+      BinaryMessenger binaryMessenger, InstanceManager instanceManager, Context context) {
+    this.binaryMessenger = binaryMessenger;
+    this.instanceManager = instanceManager;
+    this.context = context;
+  }
+
+  /**
+   * Sets the context that the {@code ProcessCameraProvider} will use to attach the lifecycle of the
+   * camera to.
+   *
+   * <p>If using the camera plugin in an add-to-app context, ensure that a new instance of the
+   * {@code ProcessCameraProvider} is fetched via {@code #getInstance} anytime the context changes.
+   */
+  public void setContext(Context context) {
+    this.context = context;
+  }
+
+  /**
+   * Returns the instance of the ProcessCameraProvider to manage the lifecycle of the camera for the
+   * current {@code Context}.
+   */
+  @Override
+  public void getInstance(GeneratedCameraXLibrary.Result<Long> result) {
+    ListenableFuture<ProcessCameraProvider> processCameraProviderFuture =
+        ProcessCameraProvider.getInstance(context);
+
+    processCameraProviderFuture.addListener(
+        () -> {
+          try {
+            // Camera provider is now guaranteed to be available.
+            ProcessCameraProvider processCameraProvider = processCameraProviderFuture.get();
+
+            if (!instanceManager.containsInstance(processCameraProvider)) {
+              final ProcessCameraProviderFlutterApiImpl flutterApi =
+                  new ProcessCameraProviderFlutterApiImpl(binaryMessenger, instanceManager);
+              flutterApi.create(processCameraProvider, reply -> {});
+            }
+            result.success(instanceManager.getIdentifierForStrongReference(processCameraProvider));
+          } catch (Exception e) {
+            result.error(e);
+          }
+        },
+        ContextCompat.getMainExecutor(context));
+  }
+
+  /** Returns cameras available to the ProcessCameraProvider. */
+  @Override
+  public List<Long> getAvailableCameraInfos(@NonNull Long identifier) {
+    ProcessCameraProvider processCameraProvider =
+        (ProcessCameraProvider) instanceManager.getInstance(identifier);
+
+    List<CameraInfo> availableCameras = processCameraProvider.getAvailableCameraInfos();
+    List<Long> availableCamerasIds = new ArrayList<Long>();
+    final CameraInfoFlutterApiImpl cameraInfoFlutterApi =
+        new CameraInfoFlutterApiImpl(binaryMessenger, instanceManager);
+
+    for (CameraInfo cameraInfo : availableCameras) {
+      cameraInfoFlutterApi.create(cameraInfo, result -> {});
+      availableCamerasIds.add(instanceManager.getIdentifierForStrongReference(cameraInfo));
+    }
+    return availableCamerasIds;
+  }
+}