[camera] Add setImageQuality for JPEG compression control

Adds `setImageQuality(int quality)` (1-100 scale) across the camera
plugin ecosystem to allow developers to control JPEG compression
quality for still image capture. Users who do not call setImageQuality
retain the platform's native default behavior.

Implementation details per platform:
- Platform interface: abstract method + method channel implementation
- App-facing: CameraController.setImageQuality with range validation
- Android (Camera2): JpegQualityFeature using CaptureRequest.JPEG_QUALITY
- Android (CameraX): Recreates ImageCapture with Builder.setJpegQuality,
  preserving locked capture orientation
- iOS (AVFoundation): EXIF-preserving JPEG recompression via
  CGImageSource/CGImageDestination (ImageIO), gated on JPEG format only

Author: Bolling88

packages/camera/camera/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.12.1
+
+* Adds `setImageQuality` for controlling JPEG compression quality.
+
 ## 0.12.0
 
 * Adds support for video stabilization.

packages/camera/camera/example/pubspec.yaml

@@ -31,3 +31,9 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+# FOR TESTING AND INITIAL REVIEW ONLY. DO NOT MERGE.
+# See https://github.com/flutter/flutter/blob/master/docs/ecosystem/contributing/README.md#changing-federated-plugins
+dependency_overrides:
+  camera_android_camerax: {path: ../../../../packages/camera/camera_android_camerax}
+  camera_avfoundation: {path: ../../../../packages/camera/camera_avfoundation}
+  camera_platform_interface: {path: ../../../../packages/camera/camera_platform_interface}

packages/camera/camera/lib/src/camera_controller.dart

@@ -998,6 +998,24 @@ class CameraController extends ValueNotifier<CameraValue> {
     }
   }
 
+  /// Sets the JPEG compression quality for still image capture.
+  ///
+  /// The [quality] must be between 1 (lowest) and 100 (highest).
+  Future<void> setImageQuality(int quality) async {
+    if (quality < 1 || quality > 100) {
+      throw ArgumentError.value(
+        quality,
+        'quality',
+        'Must be between 1 and 100.',
+      );
+    }
+    try {
+      await CameraPlatform.instance.setImageQuality(_cameraId, quality);
+    } on PlatformException catch (e) {
+      throw CameraException(e.code, e.message);
+    }
+  }
+
   /// Check whether the camera platform supports image streaming.
   bool supportsImageStreaming() =>
       CameraPlatform.instance.supportsImageStreaming();

packages/camera/camera/pubspec.yaml

@@ -4,7 +4,7 @@ description: A Flutter plugin for controlling the camera. Supports previewing
   Dart.
 repository: https://github.com/flutter/packages/tree/main/packages/camera/camera
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.12.0
+version: 0.12.1
 
 environment:
   sdk: ^3.9.0
@@ -21,9 +21,9 @@ flutter:
         default_package: camera_web
 
 dependencies:
-  camera_android_camerax: ^0.7.0
-  camera_avfoundation: ^0.10.0
-  camera_platform_interface: ^2.12.0
+  camera_android_camerax: ^0.7.1
+  camera_avfoundation: ^0.10.1
+  camera_platform_interface: ^2.13.0
   camera_web: ^0.3.3
   flutter:
     sdk: flutter
@@ -38,3 +38,9 @@ dev_dependencies:
 
 topics:
   - camera
+# FOR TESTING AND INITIAL REVIEW ONLY. DO NOT MERGE.
+# See https://github.com/flutter/flutter/blob/master/docs/ecosystem/contributing/README.md#changing-federated-plugins
+dependency_overrides:
+  camera_android_camerax: {path: ../../../packages/camera/camera_android_camerax}
+  camera_avfoundation: {path: ../../../packages/camera/camera_avfoundation}
+  camera_platform_interface: {path: ../../../packages/camera/camera_platform_interface}

packages/camera/camera/test/camera_preview_test.dart

@@ -149,6 +149,9 @@ class FakeController extends ValueNotifier<CameraValue>
   Future<Iterable<VideoStabilizationMode>>
   getSupportedVideoStabilizationModes() async => <VideoStabilizationMode>[];
 
+  @override
+  Future<void> setImageQuality(int quality) async {}
+
   @override
   bool supportsImageStreaming() => true;
 }

packages/camera/camera/test/camera_test.dart

@@ -885,6 +885,86 @@ void main() {
       },
     );
 
+    test('setImageQuality() calls $CameraPlatform', () async {
+      final cameraController = CameraController(
+        const CameraDescription(
+          name: 'cam',
+          lensDirection: CameraLensDirection.back,
+          sensorOrientation: 90,
+        ),
+        ResolutionPreset.max,
+      );
+      await cameraController.initialize();
+
+      await cameraController.setImageQuality(50);
+
+      verify(
+        CameraPlatform.instance.setImageQuality(
+          cameraController.cameraId,
+          50,
+        ),
+      ).called(1);
+    });
+
+    test(
+      'setImageQuality() throws $CameraException on $PlatformException',
+      () async {
+        final cameraController = CameraController(
+          const CameraDescription(
+            name: 'cam',
+            lensDirection: CameraLensDirection.back,
+            sensorOrientation: 90,
+          ),
+          ResolutionPreset.max,
+        );
+        await cameraController.initialize();
+
+        when(
+          CameraPlatform.instance.setImageQuality(
+            cameraController.cameraId,
+            50,
+          ),
+        ).thenThrow(
+          PlatformException(
+            code: 'TEST_ERROR',
+            message: 'This is a test error message',
+          ),
+        );
+
+        expect(
+          cameraController.setImageQuality(50),
+          throwsA(
+            isA<CameraException>().having(
+              (CameraException error) => error.description,
+              'TEST_ERROR',
+              'This is a test error message',
+            ),
+          ),
+        );
+      },
+    );
+
+    test('setImageQuality() throws ArgumentError for invalid values', () async {
+      final cameraController = CameraController(
+        const CameraDescription(
+          name: 'cam',
+          lensDirection: CameraLensDirection.back,
+          sensorOrientation: 90,
+        ),
+        ResolutionPreset.max,
+      );
+      await cameraController.initialize();
+
+      expect(
+        () => cameraController.setImageQuality(0),
+        throwsA(isA<ArgumentError>()),
+      );
+      expect(
+        () => cameraController.setImageQuality(101),
+        throwsA(isA<ArgumentError>()),
+      );
+    });
+
     test('setExposureMode() calls $CameraPlatform', () async {
       final cameraController = CameraController(
         const CameraDescription(
@@ -4152,6 +4232,12 @@ class MockCameraPlatform extends Mock
   ) async => super.noSuchMethod(
     Invocation.method(#setVideoStabilizationMode, <Object?>[cameraId, mode]),
   );
+
+  @override
+  Future<void> setImageQuality(int? cameraId, int? quality) async =>
+      super.noSuchMethod(
+        Invocation.method(#setImageQuality, <Object?>[cameraId, quality]),
+      );
 }
 
 class MockCameraDescription extends CameraDescription {

packages/camera/camera_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.10.11
+
+* Adds `setImageQuality` for controlling JPEG compression quality.
+
 ## 0.10.10+15
 
 * Updates example to demonstrate correct exception handling for async return statements, ensuring exceptions thrown during return within try blocks are properly caught as per [dart-lang/sdk#44395](https://github.com/dart-lang/sdk/issues/44395).

packages/camera/camera_android/android/build.gradle

@@ -68,7 +68,7 @@ buildFeatures {
 dependencies {
     implementation("androidx.annotation:annotation:1.9.1")
     testImplementation("junit:junit:4.13.2")
-    testImplementation("org.mockito:mockito-core:5.21.0")
+    testImplementation("org.mockito:mockito-core:5.22.0")
     testImplementation("androidx.test:core:1.7.0")
     testImplementation("org.robolectric:robolectric:4.16")
 }

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

@@ -53,6 +53,7 @@
 import io.flutter.plugins.camera.features.flash.FlashMode;
 import io.flutter.plugins.camera.features.focuspoint.FocusPointFeature;
 import io.flutter.plugins.camera.features.fpsrange.FpsRangeFeature;
+import io.flutter.plugins.camera.features.jpegquality.JpegQualityFeature;
 import io.flutter.plugins.camera.features.resolution.ResolutionFeature;
 import io.flutter.plugins.camera.features.resolution.ResolutionPreset;
 import io.flutter.plugins.camera.features.sensororientation.DeviceOrientationManager;
@@ -1407,6 +1408,20 @@ public void setDescriptionWhileRecording(CameraProperties properties) {
     }
   }
 
+  /**
+   * Sets the JPEG compression quality for still image capture.
+   *
+   * @param quality JPEG quality value between 1 and 100.
+   */
+  public void setImageQuality(@NonNull Long quality) {
+    JpegQualityFeature jpegQualityFeature = cameraFeatures.getJpegQuality();
+    if (jpegQualityFeature == null) {
+      jpegQualityFeature = cameraFeatureFactory.createJpegQualityFeature(cameraProperties);
+      cameraFeatures.setJpegQuality(jpegQualityFeature);
+    }
+    jpegQualityFeature.setValue(quality.intValue());
+  }
+
   public void dispose() {
     Log.i(TAG, "dispose");
 

packages/camera/camera_android/android/src/main/java/io/flutter/plugins/camera/CameraApiImpl.java

@@ -341,6 +341,11 @@ public void setDescriptionWhileRecording(@NonNull String cameraName) {
     }
   }
 
+  @Override
+  public void setImageQuality(@NonNull Long quality) {
+    camera.setImageQuality(quality);
+  }
+
   @Override
   public void dispose() {
     if (camera != null) {