Add an API to set the ColorFilter on a Paint object.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1158693005

examples/raw/painting.sky

@@ -19,13 +19,13 @@ void main() {
 
     context.save();
 
-    context.clipRect(new Rect()..setLTRB(0.0, 0.0, context.width, radius));
+    context.clipRect(new Rect.fromLTRB(0.0, 0.0, context.width, radius));
 
     context.translate(mid.x, mid.y);
     paint.setARGB(128, 255, 0, 255);
     context.rotateDegrees(45.0);
 
-    context.drawRect(new Rect()..setLTRB(-radius, -radius, radius, radius),
+    context.drawRect(new Rect.fromLTRB(-radius, -radius, radius, radius),
                      paint);
 
     // Scale x and y by 0.5.
@@ -40,18 +40,25 @@ void main() {
 
     context.restore();
 
+    context.translate(0.0, 50.0);
     var builder = new LayerDrawLooperBuilder()
         ..addLayerOnTop(
-            new DrawLooperLayerInfo()..setOffset(150.0, 0.0)..setPaintBits(-1),
+            new DrawLooperLayerInfo()
+              ..setOffset(150.0, 0.0)..setPaintBits(-1)..setColorMode(1),
             (Paint layerPaint) {
-          // TODO(mpcomplete): This won't do anything until we add support for
-          // setting the color filter.
-          layerPaint.setARGB(128, 0, 0, 255);
+          layerPaint.setARGB(128, 255, 255, 0);
+          layerPaint.setColorFilter(new ColorFilter(0x770000ff, 5));
         })
         ..addLayerOnTop(
-            new DrawLooperLayerInfo()..setOffset(75.0, 75.0)..setPaintBits(0),
+            new DrawLooperLayerInfo()..setOffset(75.0, 75.0)..setColorMode(1),
             (Paint layerPaint) {
           layerPaint.setARGB(128, 255, 0, 0);
+        })
+        ..addLayerOnTop(
+            new DrawLooperLayerInfo()..setOffset(225.0, 75.0),
+            (Paint layerPaint) {
+          // Since this layer uses a DST color mode, this has no effect.
+          layerPaint.setARGB(128, 255, 0, 0);
         });
     paint.setDrawLooper(builder.build());
     context.drawCircle(0.0, 0.0, radius, paint);

examples/raw/shadow.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';
+
+void beginFrame(double timeStamp) {
+  var size = 100.0;
+  PictureRecorder canvas = new PictureRecorder(view.width, view.height);
+  canvas.translate(size + 10.0, size + 10.0);
+
+  Paint paint = new Paint();
+  paint.setARGB(255, 0, 255, 0);
+  var builder = new LayerDrawLooperBuilder()
+    // Shadow layer.
+    ..addLayerOnTop(
+        new DrawLooperLayerInfo()..setOffset(5.0, 5.0)..setColorMode(5),
+        (Paint layerPaint) {
+      layerPaint.setARGB(128, 55, 55, 55);
+      // TODO(mpcomplete): add blur filter
+    })
+    // Main layer.
+    ..addLayerOnTop(new DrawLooperLayerInfo(), (Paint) {});
+  paint.setDrawLooper(builder.build());
+
+  canvas.drawPaint(new Paint()..setARGB(255, 255, 255, 255));
+  canvas.drawRect(new Rect.fromLTRB(-size, -size, size, size), paint);
+  view.picture = canvas.endRecording();
+}
+
+void main() {
+  view.setBeginFrameCallback(beginFrame);
+  view.scheduleFrame();
+}