Split CameraEvents into separate streams

packages/camera/camera_platform_interface/lib/camera_platform_interface.dart

@@ -2,5 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+export 'src/events/camera_event.dart';
 export 'src/platform_interface/camera_platform.dart';
 export 'src/types/types.dart';

packages/camera/camera_platform_interface/lib/src/events/camera_event.dart

@@ -0,0 +1,62 @@
+import 'dart:ui';
+
+/// Generic Event coming from the native side of Camera.
+///
+/// All [CameraEvent]s contain the `cameraId` that originated the event. This
+/// should never be `null`.
+///
+/// This class is used as a base class for all the events that might be
+/// triggered from a Camera, but it is never used directly as an event type.
+///
+/// Do NOT instantiate new events like `CameraEvent(cameraId)` directly,
+/// use a specific class instead:
+///
+/// Do `class NewEvent extend CameraEvent` when creating your own events.
+/// See below for examples: `CameraClosingEvent`, `CameraErrorEvent`...
+/// These events are more semantic and more pleasant to use than raw generics.
+/// They can be (and in fact, are) filtered by the `instanceof`-operator.
+abstract class CameraEvent {
+  /// The ID of the Camera this event is associated to.
+  final int cameraId;
+
+  /// Build a Camera Event, that relates a `cameraId`.
+  ///
+  /// The `cameraId` is the ID of the camera that triggered the event.
+  CameraEvent(this.cameraId);
+}
+
+/// An event fired when the resolution preset of the camera has changed.
+class ResolutionChangedEvent extends CameraEvent {
+  /// The capture size in pixels.
+  final Size captureSize;
+
+  /// The size of the preview in pixels.
+  final Size previewSize;
+
+  /// Build a ResolutionChanged event triggered from the camera represented by
+  /// `cameraId`.
+  ///
+  /// The `captureSize` represents the size of the resulting image in pixels.
+  /// The `previewSize` represents the size of the generated preview in pixels.
+  ResolutionChangedEvent(int cameraId, this.captureSize, this.previewSize)
+      : super(cameraId);
+}
+
+/// An event fired when the camera is going to close.
+class CameraClosingEvent extends CameraEvent {
+  /// Build a CameraClosing event triggered from the camera represented by
+  /// `cameraId`.
+  CameraClosingEvent(int cameraId) : super(cameraId);
+}
+
+/// An event fired when an error occured while operating the camera.
+class CameraErrorEvent extends CameraEvent {
+  /// Description of the error.
+  final String description;
+
+  /// Build a CameraError event triggered from the camera represented by
+  /// `cameraId`.
+  ///
+  /// The `description` represents the error occured on the camera.
+  CameraErrorEvent(int cameraId, this.description) : super(cameraId);
+}

packages/camera/camera_platform_interface/lib/src/platform_interface/camera_platform.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+import 'package:flutter/widgets.dart';
 import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 import 'package:camera_platform_interface/src/method_channel/method_channel_camera.dart';
 
@@ -41,7 +42,7 @@ abstract class CameraPlatform extends PlatformInterface {
     throw UnimplementedError('availableCameras() is not implemented.');
   }
 
-  /// Initializes the camera on the device and returns its textureId.
+  /// Initializes the camera on the device and returns its cameraId.
   Future<int> initializeCamera(
     CameraDescription cameraDescription, {
     ResolutionPreset resolutionPreset,
@@ -50,13 +51,23 @@ abstract class CameraPlatform extends PlatformInterface {
     throw UnimplementedError('initializeCamera() is not implemented.');
   }
 
-  /// Returns a Stream of [CameraEvent]s.
-  Stream<CameraEvent> cameraEventsFor(int textureId) {
-    throw UnimplementedError('videoEventsFor() has not been implemented.');
+  /// The camera's resolution has changed
+  Stream<ResolutionChangedEvent> onResolutionChanged(int cameraId) {
+    throw UnimplementedError('onResolutionChanged() is not implemented.');
+  }
+
+  /// The camera started to close.
+  Stream<CameraClosingEvent> onCameraClosing(int cameraId) {
+    throw UnimplementedError('onCameraClosing() is not implemented.');
+  }
+
+  /// The camera experienced an error.
+  Stream<CameraErrorEvent> onCameraError(int cameraId) {
+    throw UnimplementedError('onCameraError() is not implemented.');
   }
 
   /// Captures an image and saves it to [path].
-  Future<void> takePicture(int textureId, String path) {
+  Future<void> takePicture(int cameraId, String path) {
     throw UnimplementedError('takePicture() is not implemented.');
   }
 
@@ -73,43 +84,32 @@ abstract class CameraPlatform extends PlatformInterface {
   /// The file is written on the flight as the video is being recorded.
   /// If a file already exists at the provided path an error will be thrown.
   /// The file can be read as soon as [stopVideoRecording] returns.
-  Future<void> startVideoRecording(int textureId, String path) {
+  Future<void> startVideoRecording(int cameraId, String path) {
     throw UnimplementedError('startVideoRecording() is not implemented.');
   }
 
   /// Stop the video recording.
-  Future<void> stopVideoRecording(int textureId) {
+  Future<void> stopVideoRecording(int cameraId) {
     throw UnimplementedError('stopVideoRecording() is not implemented.');
   }
 
   /// Pause video recording.
-  Future<void> pauseVideoRecording(int textureId) {
+  Future<void> pauseVideoRecording(int cameraId) {
     throw UnimplementedError('pauseVideoRecording() is not implemented.');
   }
 
   /// Resume video recording after pausing.
-  Future<void> resumeVideoRecording(int textureId) {
+  Future<void> resumeVideoRecording(int cameraId) {
     throw UnimplementedError('resumeVideoRecording() is not implemented.');
   }
 
-  /// Start streaming images from platform camera.
-  ///
-  /// When running continuously with [CameraPreview] widget, this function runs
-  /// best with [ResolutionPreset.low]. Running on [ResolutionPreset.high] can
-  /// have significant frame rate drops for [CameraPreview] on lower end
-  /// devices.
-  // TODO(bmparr): Add settings for resolution and fps.
-  Future<void> startImageStream(ImageAvailableHandler onAvailable) {
-    throw UnimplementedError('startImageStream() is not implemented.');
-  }
-
-  /// Stop streaming images from platform camera.
-  Future<void> stopImageStream() {
-    throw UnimplementedError('stopImageStream() is not implemented.');
+  /// Returns a widget showing a live camera preview.
+  Widget buildView(int cameraId) {
+    throw UnimplementedError('buildView() has not been implemented.');
   }
 
   /// Releases the resources of this camera.
-  Future<void> dispose(int textureId) {
+  Future<void> dispose(int cameraId) {
     throw UnimplementedError('dispose() is not implemented.');
   }
 }

packages/camera/camera_platform_interface/lib/src/types/types.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-export 'callbacks.dart';
 export 'camera_description.dart';
-export 'camera_event.dart';
 export 'camera_image.dart';
 export 'resolution_preset.dart';