-Add a mojo service to get video frames from the camera through an android service

examples/dart/camera_video/lib/main.dart

Index: examples/dart/camera_video/lib/main.dart
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+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This example makes use of mojo:camera which is available only when
+// running on Android. It repeatedly captures camera video frame images
+// and displays it in a mojo view.
+//
+// Example usage:
+//   pub get
+//   pub run sky_tools build
+//   pub run sky_tools run_mojo --mojo-path=../../.. --android
+
+import 'dart:sky';
+import 'dart:typed_data';
+
+import 'package:mojo_services/mojo/camera.mojom.dart';
+import 'package:sky/services.dart';
+
+Image image = null;
+final CameraVideoServiceProxy cameraRoll = new CameraVideoServiceProxy.unbound();
+
+Picture paint(Rect paintBounds) {
+  PictureRecorder recorder = new PictureRecorder();
+  if (image != null) {
+    Canvas canvas = new Canvas(recorder, paintBounds);
+    canvas.translate(paintBounds.width / 2.0, paintBounds.height / 2.0);
+    canvas.scale(0.3, 0.3);
+    Paint paint = new Paint()..color = const Color.fromARGB(255, 0, 255, 0);
+    canvas.drawImage(image, new Point(-image.width / 2.0, -image.height / 2.0), paint);
+  }
+  return recorder.endRecording();
+}
+
+Scene composite(Picture picture, Rect paintBounds) {
+  final double devicePixelRatio = view.devicePixelRatio;
+  Rect sceneBounds = new Rect.fromLTWH(
+      0.0, 0.0, view.width * devicePixelRatio, view.height * devicePixelRatio);
+  Float32List deviceTransform = new Float32List(16)
+    ..[0] = devicePixelRatio
+    ..[5] = devicePixelRatio
+    ..[10] = 1.0
+    ..[15] = 1.0;
+  SceneBuilder sceneBuilder = new SceneBuilder(sceneBounds)
+    ..pushTransform(deviceTransform)
+    ..addPicture(Offset.zero, picture, paintBounds)
+    ..pop();
+  return sceneBuilder.build();
+}
+
+void beginFrame(double timeStamp) {
+  Rect paintBounds = new Rect.fromLTWH(0.0, 0.0, view.width, view.height);
+  Picture picture = paint(paintBounds);
+  Scene scene = composite(picture, paintBounds);
+  view.scene = scene;
+}
+
+void drawNextPhoto() {
+  var future = cameraRoll.ptr.getVideoFrames();
+  future.then((response) {
+    if (response.content == null) {
+      drawNextPhoto();
+      return;
+    }
+    new ImageDecoder(response.content.handle.h, (frame) {
+      if (frame != null) {
+        image = frame;
+        view.scheduleFrame();
+        drawNextPhoto();
+      }
+    });
+  });
+}
+
+void main() {
+  view.setFrameCallback(beginFrame);
+  embedder.connectToService("mojo:camera", cameraRoll);
+  drawNextPhoto();
+}