Make hit testing work in layout2.dart

This CL makes simple_render_tree.dart interactive by making the hit testing
system work. I've also added a mechanism for requesting an animation frame.

R=eseidel@chromium.org, ianh@google.com

Review URL: https://codereview.chromium.org/1153543002

examples/raw/hello_world.dart

@@ -20,13 +20,13 @@ Picture draw(int a, int r, int g, int b) {
 bool handleEvent(Event event) {
   if (event.type == "pointerdown") {
     view.picture = draw(255, 0, 0, 255);
-    view.schedulePaint();
+    view.scheduleFrame();
     return true;
   }
 
   if (event.type == "pointerup") {
     view.picture = draw(255, 0, 255, 0);
-    view.schedulePaint();
+    view.scheduleFrame();
     return true;
   }
 
@@ -36,7 +36,7 @@ bool handleEvent(Event event) {
 void main() {
   print("Hello, world");
   view.picture = draw(255, 0, 255, 0);
-  view.schedulePaint();
+  view.scheduleFrame();
 
   view.setEventCallback(handleEvent);
 }

examples/raw/simple_render_tree.dart

@@ -7,8 +7,11 @@ import 'dart:sky';
 import 'package:sky/framework/layout2.dart';
 
 class RenderSolidColor extends RenderDecoratedBox {
+  final int backgroundColor;
+
   RenderSolidColor(int backgroundColor)
-      : super(new BoxDecoration(backgroundColor: backgroundColor));
+      : super(new BoxDecoration(backgroundColor: backgroundColor)),
+        backgroundColor = backgroundColor;
 
   BoxDimensions getIntrinsicDimensions(BoxConstraints constraints) {
     return new BoxDimensions.withConstraints(constraints, height: 200.0);
@@ -19,16 +22,48 @@ class RenderSolidColor extends RenderDecoratedBox {
     setHeight(constraints, 200.0);
     layoutDone();
   }
+
+  bool handlePointer(PointerEvent event, { double x: 0.0, double y: 0.0 }) {
+    if (event.type == 'pointerdown') {
+      setBoxDecoration(new BoxDecoration(backgroundColor: 0xFFFF0000));
+      return true;
+    }
+
+    if (event.type == 'pointerup') {
+      setBoxDecoration(new BoxDecoration(backgroundColor: backgroundColor));
+      return true;
+    }
+
+    return false;
+  }
+}
+
+RenderView renderView;
+
+void beginFrame(double timeStamp) {
+  RenderNode.flushLayout();
+
+  renderView.paintFrame();
+}
+
+bool handleEvent(Event event) {
+  if (event is! PointerEvent)
+    return false;
+  return renderView.handlePointer(event, x: event.x, y: event.y);
 }
 
 void main() {
+  view.setEventCallback(handleEvent);
+  view.setBeginFrameCallback(beginFrame);
+
   var root = new RenderBlock(
       decoration: new BoxDecoration(backgroundColor: 0xFF00FFFF));
 
   root.add(new RenderSolidColor(0xFF00FF00));
   root.add(new RenderSolidColor(0xFF0000FF));
 
-  RenderView renderView = new RenderView(root: root);
+  renderView = new RenderView(root: root);
   renderView.layout(newWidth: view.width, newHeight: view.height);
-  renderView.paintFrame();
+
+  view.scheduleFrame();
 }