[camerax] Allow instance manager to create identical objects (#7034)

* Make changes amd add test

* Update changelog

* Add comment

* Fix spelling

* Update packages/camera/camera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/InstanceManager.java

Co-authored-by: Maurice Parrish <10687576+bparrishMines@users.noreply.github.com>

---------

Co-authored-by: Maurice Parrish <10687576+bparrishMines@users.noreply.github.com>

Author: camsim99

packages/camera/camera_android_camerax/CHANGELOG.md

@@ -7,3 +7,4 @@
 * 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.
 * Bump CameraX version to 1.3.0-alpha03 and Kotlin version to 1.8.0.
+* Changes instance manager to allow the separate creation of identical objects.

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

@@ -60,7 +60,9 @@ public List<Long> filter(@NonNull Long identifier, @NonNull List<Long> cameraInf
     List<Long> filteredCameraInfosIds = new ArrayList<Long>();
 
     for (CameraInfo cameraInfo : filteredCameraInfos) {
-      cameraInfoFlutterApiImpl.create(cameraInfo, result -> {});
+      if (!instanceManager.containsInstance(cameraInfo)) {
+        cameraInfoFlutterApiImpl.create(cameraInfo, result -> {});
+      }
       Long filteredCameraInfoId = instanceManager.getIdentifierForStrongReference(cameraInfo);
       filteredCameraInfosIds.add(filteredCameraInfoId);
     }

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

@@ -122,16 +122,15 @@ public void addDartCreatedInstance(Object instance, long identifier) {
   /**
    * Adds a new instance that was instantiated from the host platform.
    *
-   * <p>If an instance has already been added, the identifier of the instance will be returned.
+   * <p>If an instance has already been added, this will replace it. {@code #containsInstance} can
+   * be used to check if the object has already been added to avoid this.
    *
    * @param instance the instance to be stored.
    * @return the unique identifier stored with instance.
    */
   public long addHostCreatedInstance(Object instance) {
     assertManagerIsNotClosed();
-    if (containsInstance(instance)) {
-      return getIdentifierForStrongReference(instance);
-    }
+
     final long identifier = nextIdentifier++;
     addInstance(instance, identifier);
     return identifier;

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

@@ -66,7 +66,9 @@ public void getInstance(GeneratedCameraXLibrary.Result<Long> result) {
 
             final ProcessCameraProviderFlutterApiImpl flutterApi =
                 new ProcessCameraProviderFlutterApiImpl(binaryMessenger, instanceManager);
-            flutterApi.create(processCameraProvider, reply -> {});
+            if (!instanceManager.containsInstance(processCameraProvider)) {
+              flutterApi.create(processCameraProvider, reply -> {});
+            }
             result.success(instanceManager.getIdentifierForStrongReference(processCameraProvider));
           } catch (Exception e) {
             result.error(e);
@@ -87,7 +89,9 @@ public List<Long> getAvailableCameraInfos(@NonNull Long identifier) {
         new CameraInfoFlutterApiImpl(binaryMessenger, instanceManager);
 
     for (CameraInfo cameraInfo : availableCameras) {
-      cameraInfoFlutterApi.create(cameraInfo, result -> {});
+      if (!instanceManager.containsInstance(cameraInfo)) {
+        cameraInfoFlutterApi.create(cameraInfo, result -> {});
+      }
       availableCamerasIds.add(instanceManager.getIdentifierForStrongReference(cameraInfo));
     }
     return availableCamerasIds;
@@ -122,7 +126,9 @@ public Long bindToLifecycle(
 
     final CameraFlutterApiImpl cameraFlutterApi =
         new CameraFlutterApiImpl(binaryMessenger, instanceManager);
-    cameraFlutterApi.create(camera, result -> {});
+    if (!instanceManager.containsInstance(camera)) {
+      cameraFlutterApi.create(camera, result -> {});
+    }
 
     return instanceManager.getIdentifierForStrongReference(camera);
   }

packages/camera/camera_android_camerax/android/src/test/java/io/flutter/plugins/camerax/InstanceManagerTest.java

@@ -5,6 +5,7 @@
 package io.flutter.plugins.camerax;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
@@ -40,6 +41,20 @@ public void addHostCreatedInstance() {
     instanceManager.close();
   }
 
+  @Test
+  public void addHostCreatedInstance_createsSameInstanceTwice() {
+    final InstanceManager instanceManager = InstanceManager.open(identifier -> {});
+
+    final Object object = new Object();
+    long firstIdentifier = instanceManager.addHostCreatedInstance(object);
+    long secondIdentifier = instanceManager.addHostCreatedInstance(object);
+
+    assertNotEquals(firstIdentifier, secondIdentifier);
+    assertTrue(instanceManager.containsInstance(object));
+
+    instanceManager.close();
+  }
+
   @Test
   public void remove() {
     final InstanceManager instanceManager = InstanceManager.open(identifier -> {});