In Sky framework AppView, cache the hit test result for pointer events and continue using that resu…

sky/sdk/lib/framework/app.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 'layout2.dart';
 import 'dart:sky' as sky;
 
 class AppView {
 
   AppView(RenderBox root) {
     sky.view.setEventCallback(_handleEvent);
     sky.view.setBeginFrameCallback(_beginFrame);
 
     _renderView = new RenderView(root: root);
     _renderView.layout(newWidth: sky.view.width, newHeight: sky.view.height);
   
+    _hitTestResultForPointer = new Map<int, HitTestResult>();

[abarth-chromium, 2015/05/27 18:13:19]

You can actually do this work on line 24 directly.

+
     sky.view.scheduleFrame();
   }
 
   RenderView _renderView;
 
+  Map<int, HitTestResult> _hitTestResultForPointer;

[abarth-chromium, 2015/05/27 18:13:19]

final Map<int, HitTestResult> _hitTestResultForPointer = new Map<int,
HitTestResult>();

This is better because the object is created lazily, which means it doesn't
impact startup time.

+
   void _beginFrame(double timeStamp) {
     RenderNode.flushLayout();
     _renderView.paintFrame();
   }
 
   void _handleEvent(sky.Event event) {
-    if (event is! sky.PointerEvent)
-      return;
-    HitTestResult result = new HitTestResult();
-    _renderView.hitTest(result, x: event.x, y: event.y);
+    if (event is sky.PointerEvent)
+      _handlePointerEvent(event);
+  }
+
+  void _handlePointerEvent(sky.PointerEvent event) {
+    HitTestResult result;
+    switch(event.type) {
+      case 'pointerdown':
+        result = new HitTestResult();
+        _renderView.hitTest(result, x: event.x, y: event.y);
+        _hitTestResultForPointer[event.pointer] = result;
+        break;
+      case 'pointerup':
+      case 'pointercancel':
+        result = _hitTestResultForPointer[event.pointer];
+        _hitTestResultForPointer.remove(event.pointer);
+        break;
+      case 'pointermove':
+        result = _hitTestResultForPointer[event.pointer];
+        break;
+    }
     result.path.reversed.forEach((RenderNode node) {

[abarth-chromium, 2015/05/27 18:13:19]

I'd add an assert(result != null)

       node.handlePointer(event);
     });
   }
 
 }