[camerax] Adds functionality to bind UseCases to a lifecycle

CODEOWNERS

@@ -28,6 +28,7 @@ packages/**/*_web/**                                     @ditman
 
 # - Android
 packages/camera/camera_android/**                        @camsim99
+packages/camera/camera_android_camerax/**                @camsim99
 packages/espresso/**                                     @GaryQian
 packages/flutter_plugin_android_lifecycle/**             @GaryQian
 packages/google_maps_flutter/google_maps_flutter_android/**  @GaryQian

packages/camera/camera_android_camerax/CHANGELOG.md

@@ -5,3 +5,4 @@
 * Adds CameraSelector class.
 * Adds ProcessCameraProvider class.
 * Bump CameraX version to 1.3.0-alpha02.
+* Adds Camera and UseCase classes, along with methods for binding UseCases to a lifecycle with the ProcessCameraProvider.

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

@@ -6,6 +6,7 @@
 
 import android.content.Context;
 import androidx.annotation.NonNull;
+import androidx.lifecycle.LifecycleOwner;
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import io.flutter.embedding.engine.plugins.activity.ActivityAware;
 import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
@@ -15,7 +16,7 @@
 public final class CameraAndroidCameraxPlugin implements FlutterPlugin, ActivityAware {
   private InstanceManager instanceManager;
   private FlutterPluginBinding pluginBinding;
-  private ProcessCameraProviderHostApiImpl processCameraProviderHostApi;
+  public ProcessCameraProviderHostApiImpl processCameraProviderHostApi;
 
   /**
    * Initialize this within the {@code #configureFlutterEngine} of a Flutter activity or fragment.
@@ -36,10 +37,10 @@ void setUp(BinaryMessenger binaryMessenger, Context context) {
     // Set up Host APIs.
     GeneratedCameraXLibrary.CameraInfoHostApi.setup(
         binaryMessenger, new CameraInfoHostApiImpl(instanceManager));
-    GeneratedCameraXLibrary.JavaObjectHostApi.setup(
-        binaryMessenger, new JavaObjectHostApiImpl(instanceManager));
     GeneratedCameraXLibrary.CameraSelectorHostApi.setup(
         binaryMessenger, new CameraSelectorHostApiImpl(binaryMessenger, instanceManager));
+    GeneratedCameraXLibrary.JavaObjectHostApi.setup(
+        binaryMessenger, new JavaObjectHostApiImpl(instanceManager));
     processCameraProviderHostApi =
         new ProcessCameraProviderHostApiImpl(binaryMessenger, instanceManager, context);
     GeneratedCameraXLibrary.ProcessCameraProviderHostApi.setup(
@@ -49,10 +50,6 @@ void setUp(BinaryMessenger binaryMessenger, Context context) {
   @Override
   public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
     pluginBinding = flutterPluginBinding;
-    (new CameraAndroidCameraxPlugin())
-        .setUp(
-            flutterPluginBinding.getBinaryMessenger(),
-            flutterPluginBinding.getApplicationContext());
   }
 
   @Override
@@ -66,7 +63,11 @@ public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
 
   @Override
   public void onAttachedToActivity(@NonNull ActivityPluginBinding activityPluginBinding) {
-    updateContext(activityPluginBinding.getActivity());
+    CameraAndroidCameraxPlugin plugin = new CameraAndroidCameraxPlugin();
+    plugin.setUp(pluginBinding.getBinaryMessenger(), pluginBinding.getApplicationContext());
+    plugin.updateContext(pluginBinding.getApplicationContext());
+    plugin.processCameraProviderHostApi.setLifecycleOwner(
+        (LifecycleOwner) activityPluginBinding.getActivity());
   }
 
   @Override
@@ -89,7 +90,7 @@ public void onDetachedFromActivity() {
    * Updates context that is used to fetch the corresponding instance of a {@code
    * ProcessCameraProvider}.
    */
-  private void updateContext(Context context) {
+  public void updateContext(Context context) {
     if (processCameraProviderHostApi != null) {
       processCameraProviderHostApi.setContext(context);
     }

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

@@ -0,0 +1,22 @@
+// 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.core.Camera;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugins.camerax.GeneratedCameraXLibrary.CameraFlutterApi;
+
+public class CameraFlutterApiImpl extends CameraFlutterApi {
+  private final InstanceManager instanceManager;
+
+  public CameraFlutterApiImpl(BinaryMessenger binaryMessenger, InstanceManager instanceManager) {
+    super(binaryMessenger);
+    this.instanceManager = instanceManager;
+  }
+
+  void create(Camera camera, Reply<Void> reply) {
+    create(instanceManager.addHostCreatedInstance(camera), reply);
+  }
+}

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

@@ -332,6 +332,16 @@ public interface ProcessCameraProviderHostApi {
     @NonNull
     List<Long> getAvailableCameraInfos(@NonNull Long identifier);
 
+    @NonNull
+    Long bindToLifecycle(
+        @NonNull Long identifier,
+        @NonNull Long cameraSelectorIdentifier,
+        @NonNull List<Long> useCaseIds);
+
+    void unbind(@NonNull Long identifier, @NonNull List<Long> useCaseIds);
+
+    void unbindAll(@NonNull Long identifier);
+
     /** The codec used by ProcessCameraProviderHostApi. */
     static MessageCodec<Object> getCodec() {
       return ProcessCameraProviderHostApiCodec.INSTANCE;
@@ -405,6 +415,107 @@ public void error(Throwable error) {
           channel.setMessageHandler(null);
         }
       }
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<>(
+                binaryMessenger,
+                "dev.flutter.pigeon.ProcessCameraProviderHostApi.bindToLifecycle",
+                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.");
+                  }
+                  Number cameraSelectorIdentifierArg = (Number) args.get(1);
+                  if (cameraSelectorIdentifierArg == null) {
+                    throw new NullPointerException(
+                        "cameraSelectorIdentifierArg unexpectedly null.");
+                  }
+                  List<Long> useCaseIdsArg = (List<Long>) args.get(2);
+                  if (useCaseIdsArg == null) {
+                    throw new NullPointerException("useCaseIdsArg unexpectedly null.");
+                  }
+                  Long output =
+                      api.bindToLifecycle(
+                          (identifierArg == null) ? null : identifierArg.longValue(),
+                          (cameraSelectorIdentifierArg == null)
+                              ? null
+                              : cameraSelectorIdentifierArg.longValue(),
+                          useCaseIdsArg);
+                  wrapped.put("result", output);
+                } 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.unbind",
+                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> useCaseIdsArg = (List<Long>) args.get(1);
+                  if (useCaseIdsArg == null) {
+                    throw new NullPointerException("useCaseIdsArg unexpectedly null.");
+                  }
+                  api.unbind(
+                      (identifierArg == null) ? null : identifierArg.longValue(), useCaseIdsArg);
+                  wrapped.put("result", null);
+                } 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.unbindAll",
+                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.");
+                  }
+                  api.unbindAll((identifierArg == null) ? null : identifierArg.longValue());
+                  wrapped.put("result", null);
+                } catch (Error | RuntimeException exception) {
+                  wrapped.put("error", wrapError(exception));
+                }
+                reply.reply(wrapped);
+              });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
     }
   }
 
@@ -445,6 +556,40 @@ public void create(@NonNull Long identifierArg, Reply<Void> callback) {
     }
   }
 
+  private static class CameraFlutterApiCodec extends StandardMessageCodec {
+    public static final CameraFlutterApiCodec INSTANCE = new CameraFlutterApiCodec();
+
+    private CameraFlutterApiCodec() {}
+  }
+
+  /** Generated class from Pigeon that represents Flutter messages that can be called from Java. */
+  public static class CameraFlutterApi {
+    private final BinaryMessenger binaryMessenger;
+
+    public CameraFlutterApi(BinaryMessenger argBinaryMessenger) {
+      this.binaryMessenger = argBinaryMessenger;
+    }
+
+    public interface Reply<T> {
+      void reply(T reply);
+    }
+
+    static MessageCodec<Object> getCodec() {
+      return CameraFlutterApiCodec.INSTANCE;
+    }
+
+    public void create(@NonNull Long identifierArg, Reply<Void> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<>(
+              binaryMessenger, "dev.flutter.pigeon.CameraFlutterApi.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/ProcessCameraProviderHostApiImpl.java

@@ -6,9 +6,13 @@
 
 import android.content.Context;
 import androidx.annotation.NonNull;
+import androidx.camera.core.Camera;
 import androidx.camera.core.CameraInfo;
+import androidx.camera.core.CameraSelector;
+import androidx.camera.core.UseCase;
 import androidx.camera.lifecycle.ProcessCameraProvider;
 import androidx.core.content.ContextCompat;
+import androidx.lifecycle.LifecycleOwner;
 import com.google.common.util.concurrent.ListenableFuture;
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugins.camerax.GeneratedCameraXLibrary.ProcessCameraProviderHostApi;
@@ -20,6 +24,7 @@ public class ProcessCameraProviderHostApiImpl implements ProcessCameraProviderHo
   private final InstanceManager instanceManager;
 
   private Context context;
+  private LifecycleOwner lifecycleOwner;
 
   public ProcessCameraProviderHostApiImpl(
       BinaryMessenger binaryMessenger, InstanceManager instanceManager, Context context) {
@@ -28,6 +33,10 @@ public ProcessCameraProviderHostApiImpl(
     this.context = context;
   }
 
+  public void setLifecycleOwner(LifecycleOwner lifecycleOwner) {
+    this.lifecycleOwner = lifecycleOwner;
+  }
+
   /**
    * Sets the context that the {@code ProcessCameraProvider} will use to attach the lifecycle of the
    * camera to.
@@ -40,8 +49,8 @@ public void setContext(Context context) {
   }
 
   /**
-   * Returns the instance of the ProcessCameraProvider to manage the lifecycle of the camera for the
-   * current {@code Context}.
+   * Returns the instance of the {@code ProcessCameraProvider} to manage the lifecycle of the camera
+   * for the current {@code Context}.
    */
   @Override
   public void getInstance(GeneratedCameraXLibrary.Result<Long> result) {
@@ -54,11 +63,9 @@ public void getInstance(GeneratedCameraXLibrary.Result<Long> result) {
             // 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 -> {});
-            }
+            final ProcessCameraProviderFlutterApiImpl flutterApi =
+                new ProcessCameraProviderFlutterApiImpl(binaryMessenger, instanceManager);
+            flutterApi.create(processCameraProvider, reply -> {});
             result.success(instanceManager.getIdentifierForStrongReference(processCameraProvider));
           } catch (Exception e) {
             result.error(e);
@@ -67,7 +74,7 @@ public void getInstance(GeneratedCameraXLibrary.Result<Long> result) {
         ContextCompat.getMainExecutor(context));
   }
 
-  /** Returns cameras available to the ProcessCameraProvider. */
+  /** Returns cameras available to the {@code ProcessCameraProvider}. */
   @Override
   public List<Long> getAvailableCameraInfos(@NonNull Long identifier) {
     ProcessCameraProvider processCameraProvider =
@@ -84,4 +91,52 @@ public List<Long> getAvailableCameraInfos(@NonNull Long identifier) {
     }
     return availableCamerasIds;
   }
+
+  /**
+   * Binds specified {@code UseCase}s to the lifecycle of the {@code LifecycleOwner} that
+   * corresponds to this instance and returns the instance of the {@code Camera} whose lifecycle
+   * that {@code LifecycleOwner} reflects.
+   */
+  @Override
+  public Long bindToLifecycle(
+      @NonNull Long identifier,
+      @NonNull Long cameraSelectorIdentifier,
+      @NonNull List<Long> useCaseIds) {
+    ProcessCameraProvider processCameraProvider =
+        (ProcessCameraProvider) instanceManager.getInstance(identifier);
+    CameraSelector cameraSelector =
+        (CameraSelector) instanceManager.getInstance(cameraSelectorIdentifier);
+    UseCase[] useCases = new UseCase[useCaseIds.size()];
+    for (int i = 0; i < useCaseIds.size(); i++) {
+      useCases[i] = (UseCase) instanceManager.getInstance(((Number) useCaseIds.get(i)).longValue());
+    }
+
+    Camera camera =
+        processCameraProvider.bindToLifecycle(
+            (LifecycleOwner) lifecycleOwner, cameraSelector, useCases);
+
+    final CameraFlutterApiImpl camraFlutterApi =
+        new CameraFlutterApiImpl(binaryMessenger, instanceManager);
+    camraFlutterApi.create(camera, result -> {});
+
+    return instanceManager.getIdentifierForStrongReference(camera);
+  }
+
+  @Override
+  public void unbind(@NonNull Long identifier, @NonNull List<Long> useCaseIds) {
+    ProcessCameraProvider processCameraProvider =
+        (ProcessCameraProvider) instanceManager.getInstance(identifier);
+    UseCase[] useCases = new UseCase[useCaseIds.size()];
+    for (int i = 0; i < useCaseIds.size(); i++) {
+      useCases[i] = (UseCase) instanceManager.getInstance(((Number) useCaseIds.get(i)).longValue());
+    }
+    processCameraProvider.unbind(useCases);
+  }
+
+  @Override
+  public void unbindAll(@NonNull Long identifier) {
+    ProcessCameraProvider processCameraProvider =
+        (ProcessCameraProvider) instanceManager.getInstance(identifier);
+    processCameraProvider.unbindAll();
+  }
 }