[camera] Add support for zero-shutter-lag capture

packages/camera/camera/CHANGELOG.md

@@ -1,3 +1,9 @@
+## 0.12.1
+
+* Adds `CameraController.isZeroShutterLagSupported` and
+  `CameraController.setZeroShutterLagEnabled` for zero-shutter-lag still image
+  capture on platforms that support it.
+
 ## 0.12.0+2
 
 * Fixes a crash where a `CameraController` could update its value after being disposed, throwing "A CameraController was used after being disposed".

packages/camera/camera/example/pubspec.yaml

@@ -31,3 +31,7 @@ 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_platform_interface: {path: ../../../../packages/camera/camera_platform_interface}

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

@@ -796,6 +796,35 @@ class CameraController extends ValueNotifier<CameraValue> {
     }
   }
 
+  /// Returns whether the selected camera supports zero-shutter-lag capture.
+  ///
+  /// Zero-shutter-lag reduces the latency of [takePicture] by returning a
+  /// recently buffered frame instead of waiting for a new capture.
+  Future<bool> isZeroShutterLagSupported() async {
+    _throwIfNotInitialized('isZeroShutterLagSupported');
+    try {
+      return await CameraPlatform.instance.isZeroShutterLagSupported(_cameraId);
+    } on PlatformException catch (e) {
+      throw CameraException(e.code, e.message);
+    }
+  }
+
+  /// Enables or disables zero-shutter-lag capture for still image capture.
+  ///
+  /// [isZeroShutterLagSupported] must be called first; only call this method
+  /// when it returns `true`.
+  ///
+  /// When enabled, [takePicture] returns a recently buffered frame instead of
+  /// waiting for a new capture, reducing shutter latency.
+  Future<void> setZeroShutterLagEnabled(bool enabled) async {
+    _throwIfNotInitialized('setZeroShutterLagEnabled');
+    try {
+      await CameraPlatform.instance.setZeroShutterLagEnabled(_cameraId, enabled);
+    } on PlatformException catch (e) {
+      throw CameraException(e.code, e.message);
+    }
+  }
+
   /// Sets the flash mode for taking pictures.
   Future<void> setFlashMode(FlashMode mode) async {
     try {

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+2
+version: 0.12.1
 
 environment:
   sdk: ^3.10.0
@@ -23,7 +23,7 @@ flutter:
 dependencies:
   camera_android_camerax: ^0.7.0
   camera_avfoundation: ^0.10.0
-  camera_platform_interface: ^2.12.0
+  camera_platform_interface: ^2.14.0
   camera_web: ^0.3.3
   flutter:
     sdk: flutter
@@ -38,3 +38,7 @@ 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_platform_interface: {path: ../../../packages/camera/camera_platform_interface}

packages/camera/camera/test/camera_preview_test.dart

@@ -105,6 +105,12 @@ class FakeController extends ValueNotifier<CameraValue> implements CameraControl
   @override
   Future<void> setZoomLevel(double zoom) async {}
 
+  @override
+  Future<bool> isZeroShutterLagSupported() async => false;
+
+  @override
+  Future<void> setZeroShutterLagEnabled(bool enabled) async {}
+
   @override
   Future<void> startImageStream(onLatestImageAvailable onAvailable) async {}
 

packages/camera/camera/test/camera_test.dart

@@ -727,6 +727,110 @@ void main() {
       verify(CameraPlatform.instance.setZoomLevel(mockInitializeCamera, 42.0)).called(1);
     });
 
+    test('isZeroShutterLagSupported() returns the platform value.', () async {
+      final cameraController = CameraController(
+        const CameraDescription(
+          name: 'cam',
+          lensDirection: CameraLensDirection.back,
+          sensorOrientation: 90,
+        ),
+        ResolutionPreset.max,
+      );
+
+      await cameraController.initialize();
+      when(
+        CameraPlatform.instance.isZeroShutterLagSupported(mockInitializeCamera),
+      ).thenAnswer((_) async => true);
+
+      expect(await cameraController.isZeroShutterLagSupported(), isTrue);
+      verify(CameraPlatform.instance.isZeroShutterLagSupported(mockInitializeCamera)).called(1);
+
+      reset(CameraPlatform.instance);
+    });
+
+    test('isZeroShutterLagSupported() throws $CameraException when uninitialized.', () async {
+      final cameraController = CameraController(
+        const CameraDescription(
+          name: 'cam',
+          lensDirection: CameraLensDirection.back,
+          sensorOrientation: 90,
+        ),
+        ResolutionPreset.max,
+      );
+
+      expect(
+        () => cameraController.isZeroShutterLagSupported(),
+        throwsA(
+          isA<CameraException>()
+              .having(
+                (CameraException error) => error.code,
+                'code',
+                'Uninitialized CameraController',
+              )
+              .having(
+                (CameraException error) => error.description,
+                'description',
+                'isZeroShutterLagSupported() was called on an uninitialized CameraController.',
+              ),
+        ),
+      );
+    });
+
+    test(
+      'setZeroShutterLagEnabled() completes and calls method channel with correct value.',
+      () async {
+        final cameraController = CameraController(
+          const CameraDescription(
+            name: 'cam',
+            lensDirection: CameraLensDirection.back,
+            sensorOrientation: 90,
+          ),
+          ResolutionPreset.max,
+        );
+
+        await cameraController.initialize();
+        await cameraController.setZeroShutterLagEnabled(true);
+
+        verify(
+          CameraPlatform.instance.setZeroShutterLagEnabled(mockInitializeCamera, true),
+        ).called(1);
+      },
+    );
+
+    test(
+      'setZeroShutterLagEnabled() throws $CameraException when a platform exception occured.',
+      () async {
+        final cameraController = CameraController(
+          const CameraDescription(
+            name: 'cam',
+            lensDirection: CameraLensDirection.back,
+            sensorOrientation: 90,
+          ),
+          ResolutionPreset.max,
+        );
+
+        await cameraController.initialize();
+        when(
+          CameraPlatform.instance.setZeroShutterLagEnabled(mockInitializeCamera, true),
+        ).thenThrow(CameraException('TEST_ERROR', 'This is a test error messge'));
+
+        expect(
+          () => cameraController.setZeroShutterLagEnabled(true),
+          throwsA(
+            isA<CameraException>()
+                .having((CameraException error) => error.code, 'code', 'TEST_ERROR')
+                .having(
+                  (CameraException error) => error.description,
+                  'description',
+                  'This is a test error messge',
+                ),
+          ),
+        );
+
+        reset(CameraPlatform.instance);
+      },
+    );
+
     test('setFlashMode() calls $CameraPlatform', () async {
       final cameraController = CameraController(
         const CameraDescription(
@@ -3646,6 +3750,19 @@ class MockCameraPlatform extends Mock with MockPlatformInterfaceMixin implements
   @override
   Future<void> setVideoStabilizationMode(int cameraId, VideoStabilizationMode mode) async =>
       super.noSuchMethod(Invocation.method(#setVideoStabilizationMode, <Object?>[cameraId, mode]));
+
+  @override
+  Future<bool> isZeroShutterLagSupported(int cameraId) async =>
+      super.noSuchMethod(
+            Invocation.method(#isZeroShutterLagSupported, <Object?>[cameraId]),
+            returnValue: Future<bool>.value(false),
+          )
+          as Future<bool>;
+
+  @override
+  Future<void> setZeroShutterLagEnabled(int cameraId, bool enabled) async => super.noSuchMethod(
+    Invocation.method(#setZeroShutterLagEnabled, <Object?>[cameraId, enabled]),
+  );
 }
 
 class MockCameraDescription extends CameraDescription {

packages/camera/camera_android/example/pubspec.yaml

@@ -31,3 +31,7 @@ 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_platform_interface: {path: ../../../../packages/camera/camera_platform_interface}

packages/camera/camera_android/pubspec.yaml

@@ -37,3 +37,7 @@ 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_platform_interface: {path: ../../../packages/camera/camera_platform_interface}

packages/camera/camera_android_camerax/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.7.5
+
+* Adds support for zero-shutter-lag still image capture via
+  `isZeroShutterLagSupported` and `setZeroShutterLagEnabled`.
+
 ## 0.7.4+7
 
 * Updates pigeon dev_dependency to ^27.3.2 for analyzer 14 compatibility.

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

@@ -9,6 +9,7 @@
 import androidx.camera.core.CameraInfo;
 import androidx.camera.core.CameraSelector;
 import androidx.camera.core.ExperimentalLensFacing;
+import androidx.camera.core.ExperimentalZeroShutterLag;
 import androidx.camera.core.ExposureState;
 
 /**
@@ -61,4 +62,10 @@ public LiveDataProxyApi.LiveDataWrapper getZoomState(CameraInfo pigeonInstance)
     return new LiveDataProxyApi.LiveDataWrapper(
         pigeonInstance.getZoomState(), LiveDataSupportedType.ZOOM_STATE);
   }
+
+  @Override
+  @OptIn(markerClass = ExperimentalZeroShutterLag.class)
+  public boolean isZslSupported(CameraInfo pigeonInstance) {
+    return pigeonInstance.isZslSupported();
+  }
 }

packages/camera/camera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/CameraXLibrary.g.kt

@@ -2199,6 +2199,13 @@ abstract class PigeonApiCameraInfo(
       pigeon_instance: androidx.camera.core.CameraInfo
   ): io.flutter.plugins.camerax.LiveDataProxyApi.LiveDataWrapper
 
+  /**
+   * Returns whether the camera supports zero-shutter-lag capture.
+   *
+   * See https://developer.android.com/reference/androidx/camera/core/CameraInfo#isZslSupported().
+   */
+  abstract fun isZslSupported(pigeon_instance: androidx.camera.core.CameraInfo): Boolean
+
   companion object {
     @Suppress("LocalVariableName")
     fun setUpMessageHandlers(binaryMessenger: BinaryMessenger, api: PigeonApiCameraInfo?) {
@@ -2247,6 +2254,28 @@ abstract class PigeonApiCameraInfo(
           channel.setMessageHandler(null)
         }
       }
+      run {
+        val channel =
+            BasicMessageChannel<Any?>(
+                binaryMessenger,
+                "dev.flutter.pigeon.camera_android_camerax.CameraInfo.isZslSupported",
+                codec)
+        if (api != null) {
+          channel.setMessageHandler { message, reply ->
+            val args = message as List<Any?>
+            val pigeon_instanceArg = args[0] as androidx.camera.core.CameraInfo
+            val wrapped: List<Any?> =
+                try {
+                  listOf(api.isZslSupported(pigeon_instanceArg))
+                } catch (exception: Throwable) {
+                  CameraXLibraryPigeonUtils.wrapError(exception)
+                }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
     }
   }
 
@@ -4248,7 +4277,8 @@ abstract class PigeonApiImageCapture(
       resolutionSelector: androidx.camera.core.resolutionselector.ResolutionSelector?,
       targetRotation: Long?,
       flashMode: CameraXFlashMode?,
-      jpegQuality: Long?
+      jpegQuality: Long?,
+      zeroShutterLagEnabled: Boolean?
   ): androidx.camera.core.ImageCapture
 
   abstract fun resolutionSelector(
@@ -4290,11 +4320,16 @@ abstract class PigeonApiImageCapture(
             val targetRotationArg = args[2] as Long?
             val flashModeArg = args[3] as CameraXFlashMode?
             val jpegQualityArg = args[4] as Long?
+            val zeroShutterLagEnabledArg = args[5] as Boolean?
             val wrapped: List<Any?> =
                 try {
                   api.pigeonRegistrar.instanceManager.addDartCreatedInstance(
                       api.pigeon_defaultConstructor(
-                          resolutionSelectorArg, targetRotationArg, flashModeArg, jpegQualityArg),
+                          resolutionSelectorArg,
+                          targetRotationArg,
+                          flashModeArg,
+                          jpegQualityArg,
+                          zeroShutterLagEnabledArg),
                       pigeon_identifierArg)
                   listOf(null)
                 } catch (exception: Throwable) {

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

@@ -6,6 +6,8 @@
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.OptIn;
+import androidx.camera.core.ExperimentalZeroShutterLag;
 import androidx.camera.core.ImageCapture;
 import androidx.camera.core.ImageCaptureException;
 import androidx.camera.core.resolutionselector.ResolutionSelector;
@@ -37,15 +39,20 @@ public ProxyApiRegistrar getPigeonRegistrar() {
 
   @NonNull
   @Override
+  @OptIn(markerClass = ExperimentalZeroShutterLag.class)
   public ImageCapture pigeon_defaultConstructor(
       @Nullable ResolutionSelector resolutionSelector,
       @Nullable Long targetRotation,
       @Nullable CameraXFlashMode flashMode,
-      @Nullable Long jpegQuality) {
+      @Nullable Long jpegQuality,
+      @Nullable Boolean zeroShutterLagEnabled) {
     final ImageCapture.Builder builder = new ImageCapture.Builder();
     if (targetRotation != null) {
       builder.setTargetRotation(targetRotation.intValue());
     }
+    if (Boolean.TRUE.equals(zeroShutterLagEnabled)) {
+      builder.setCaptureMode(ImageCapture.CAPTURE_MODE_ZERO_SHUTTER_LAG);
+    }
     if (flashMode != null) {
       // This sets the requested flash mode, but may fail silently.
       switch (flashMode) {