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

sky/sdk/lib/framework/rendering/object.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:math' as math;
 import 'dart:sky' as sky;
 import 'dart:sky' show Point, Size, Rect, Color, Paint, Path;
 
 import '../node.dart';
 import '../scheduler.dart' as scheduler;
 
 export 'dart:sky' show Point, Size, Rect, Color, Paint, Path;
 
 class ParentData {
   void detach() {
     detachSiblings();
   }
   void detachSiblings() { } // workaround for lack of inter-class mixins in Dart
   void merge(ParentData other) {
     // override this in subclasses to merge in data from other into this
     assert(other.runtimeType == this.runtimeType);
   }
   String toString() => '<none>';
 }
 
 const kLayoutDirections = 4;
 
-class RenderObjectDisplayList extends sky.PictureRecorder {
-  RenderObjectDisplayList(double width, double height) : super(width, height);
-  void paintChild(RenderObject child, Point position) {
-    translate(position.x, position.y);
-    child.paint(this);
-    translate(-position.x, -position.y);
-  }
-}
-
 abstract class RenderObject extends AbstractNode {
 
   // LAYOUT
 
   // parentData is only for use by the RenderObject that actually lays this
   // node out, and any other nodes who happen to know exactly what
   // kind of node that is.
   dynamic parentData; // TODO(ianh): change the type of this back to ParentData once the analyzer is cleverer
   void setParentData(RenderObject child) {
     // override this to setup .parentData correctly for your class
     assert(!debugDoingLayout);
     assert(!debugDoingPaint);
     if (child.parentData is! ParentData)
       child.parentData = new ParentData();
   }
 
+  void paintChild(sky.Canvas canvas, RenderObject child, Point position) {
+    canvas.translate(position.x, position.y);
+    child.paint(canvas);
+    canvas.translate(-position.x, -position.y);
+  }
+

[Hixie, 2015/06/18 00:07:09]

I really don't like this change. It is going to encourage people to just call
child.paint(canvas) instead of paintChild(canvas).

The reason behind canvas.paintChild(child) is that it will subsequently let us
change whether or not a node painting a child introduces a new
canvas/displaylist/recorder/whatever without having to change any of the call
sites.

[iansf, 2015/06/20 00:02:38]

Let me know what you think of the new version.

   void adoptChild(RenderObject child) { // only for use by subclasses
     // call this whenever you decide a node is a child
     assert(!debugDoingLayout);
     assert(!debugDoingPaint);
     assert(child != null);
     setParentData(child);
     super.adoptChild(child);
     markNeedsLayout();
   }
   void dropChild(RenderObject child) { // only for use by subclasses
@@ skipping 131 matching lines @@
   }) { }
 
 
   // PAINTING
 
   static bool debugDoingPaint = false;
   void markNeedsPaint() {
     assert(!debugDoingPaint);
     scheduler.ensureVisualUpdate();
   }
-  void paint(RenderObjectDisplayList canvas) { }
+  void paint(sky.Canvas canvas) { }
 
 
   // EVENTS
 
   void handleEvent(sky.Event event, HitTestEntry entry) {
     // override this if you have a client, to hand it to the client
     // override this if you want to do anything with the event
   }
 
 
@@ skipping 242 matching lines @@
     int count = 1;
     ChildType child = _firstChild;
     while (child != null) {
       result += '${prefix}child ${count}: ${child.toString(prefix)}';
       count += 1;
       child = child.parentData.nextSibling;
     }
     return result;
   }
 }