Decouple Canvas from DisplayList and map Picture and PictureRecorder more directly to their Skia co…

sky/examples/raw/painting.dart

 // 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.
 
 import 'dart:sky' as sky;
 import 'dart:math' as math;
 import 'dart:typed_data';
 
 void beginFrame(double timeStamp) {
-  sky.PictureRecorder context = new sky.PictureRecorder(sky.view.width, 200.0);
+  sky.PictureRecorder recorder = new sky.PictureRecorder();
+  Canvas canvas = new Canvas(recorder, sky.view.width, 200.0);
 
   sky.Paint paint = new sky.Paint();
-  sky.Point mid = new sky.Point(context.width / 2.0, context.height / 2.0);
+  sky.Point mid = new sky.Point(sky.view.width / 2.0, sky.view.height / 2.0);
   double radius = math.min(mid.x, mid.y);
 
-  context.drawPaint(new sky.Paint()..color = const sky.Color(0xFFFFFFFF));
+  canvas.drawPaint(new sky.Paint()..color = const sky.Color(0xFFFFFFFF));
 
-  context.save();
+  canvas.save();
 
-  context.translate(-mid.x/2.0, context.height*2.0);
-  context.clipRect(
-      new sky.Rect.fromLTRB(0.0, -context.height, context.width, radius));
+  canvas.translate(-mid.x/2.0, sky.view.height*2.0);
+  canvas.clipRect(
+      new sky.Rect.fromLTRB(0.0, -sky.view.height, sky.view.width, radius));
 
-  context.translate(mid.x, mid.y);
+  canvas.translate(mid.x, mid.y);
   paint.color = const sky.Color.fromARGB(128, 255, 0, 255);
-  context.rotate(math.PI/4.0);
+  canvas.rotate(math.PI/4.0);
 
   sky.Gradient yellowBlue = new sky.Gradient.linear(
       [new sky.Point(-radius, -radius), new sky.Point(0.0, 0.0)],
       [const sky.Color(0xFFFFFF00), const sky.Color(0xFF0000FF)]);
-  context.drawRect(new sky.Rect.fromLTRB(-radius, -radius, radius, radius),
+  canvas.drawRect(new sky.Rect.fromLTRB(-radius, -radius, radius, radius),
                    new sky.Paint()..setShader(yellowBlue));
 
   // Scale x and y by 0.5.
   var scaleMatrix = new Float32List.fromList([
       0.5, 0.0, 0.0, 0.0,
       0.0, 0.5, 0.0, 0.0,
       0.0, 0.0, 0.0, 0.0,
       0.0, 0.0, 0.0, 1.0,
   ]);
-  context.concat(scaleMatrix);
+  canvas.concat(scaleMatrix);
   paint.color = const sky.Color.fromARGB(128, 0, 255, 0);
-  context.drawCircle(0.0, 0.0, radius, paint);
+  canvas.drawCircle(0.0, 0.0, radius, paint);
 
-  context.restore();
+  canvas.restore();
 
-  context.translate(0.0, 50.0);
+  canvas.translate(0.0, 50.0);
   var builder = new sky.LayerDrawLooperBuilder()
       ..addLayerOnTop(
           new sky.DrawLooperLayerInfo()
             ..setOffset(const sky.Point(150.0, 0.0))
             ..setColorMode(sky.TransferMode.src)
             ..setPaintBits(sky.PaintBits.all),
           (sky.Paint layerPaint) {
         layerPaint.color = const sky.Color.fromARGB(128, 255, 255, 0);
         layerPaint.setColorFilter(new sky.ColorFilter.mode(
             const sky.Color.fromARGB(128, 0, 0, 255), sky.TransferMode.srcIn));
@@ skipping 15 matching lines @@
         layerPaint.setMaskFilter(new sky.MaskFilter.blur(
             sky.BlurStyle.normal, 50.0, highQuality: true));
       })
       ..addLayerOnTop(
           new sky.DrawLooperLayerInfo()..setOffset(const sky.Point(225.0, 75.0)),
           (sky.Paint layerPaint) {
         // Since this layer uses a DST color mode, this has no effect.
         layerPaint.color = const sky.Color.fromARGB(128, 255, 0, 0);
       });
   paint.setDrawLooper(builder.build());
-  context.drawCircle(0.0, 0.0, radius, paint);
+  canvas.drawCircle(0.0, 0.0, radius, paint);
 
-  sky.view.picture = context.endRecording();
+  sky.view.picture = recorder.endRecording();
 }
 
 void main() {
   sky.view.setBeginFrameCallback(beginFrame);
   sky.view.scheduleFrame();
 }