Make Drawer in components2 work

sky/sdk/lib/framework/rendering/box.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:typed_data';
 import 'node.dart';
 import 'package:vector_math/vector_math.dart';
 
@@ skipping 32 matching lines @@
     this.maxWidth: double.INFINITY,
     this.minHeight: 0.0,
     this.maxHeight: double.INFINITY});
 
   BoxConstraints.tight(sky.Size size)
     : minWidth = size.width,
       maxWidth = size.width,
       minHeight = size.height,
       maxHeight = size.height;
 
+  BoxConstraints.loose(sky.Size size)
+    : minWidth = 0.0,
+      maxWidth = size.width,
+      minHeight = 0.0,
+      maxHeight = size.height;
+
   BoxConstraints deflate(EdgeDims edges) {
     assert(edges != null);
     double horizontal = edges.left + edges.right;
     double vertical = edges.top + edges.bottom;
     return new BoxConstraints(
       minWidth: math.min(0.0, minWidth - horizontal),
       maxWidth: maxWidth - horizontal,
       minHeight: math.min(0.0, minHeight - vertical),
       maxHeight: maxHeight - vertical
     );
@@ skipping 280 matching lines @@
     Vector3 position3 = new Vector3(position.x, position.y, 0.0);
     Vector3 transformed3 = inverse.transform3(position3);
     sky.Point transformed = new sky.Point(transformed3.x, transformed3.y);
     super.hitTestChildren(result, position: transformed);
   }
 
   void paint(RenderNodeDisplayList canvas) {
     Float32List storage = _transform.storage;
 
     canvas.save();
     canvas.concat([

[Matt Perry, 2015/06/03 21:29:50]

We could change Canvas.concat to take a Float32List in the format Matrix4 uses.

[Matt Perry, 2015/06/03 22:15:52]

Here's what it would look like:
https://codereview.chromium.org/1155193004/diff/20001/sky/examples/raw/painti...

The question is, should we add our own Matrix class (that maybe just calls
through to the C++ SkMatrix class) to dart:sky, or should we let the framework
handle it (using vector_math.dart like we do here)?

-      storage[ 0], storage[ 1], storage[ 3],
-      storage[ 4], storage[ 5], storage[ 7],
-      storage[12], storage[13], storage[15],

[Hixie, 2015/06/03 21:39:56]

Why doesn't canvas take a Matrix, the same way it takes a Rect for other things?

[abarth-chromium, 2015/06/03 22:33:42]

The answer here is slightly complicated.  The short version is that we're going
to end with two Matrix classes, one that's optimized for manipulation within the
VM and one that's optimized for talking to skia.  Currently the |concat|
function uses neither of these.  Presumably we'll want versions for each one.

+      storage[ 0], storage[ 4], storage[12],
+      storage[ 1], storage[ 5], storage[13],
+      storage[ 3], storage[ 7], storage[15],
     ]);
     super.paint(canvas);
     canvas.restore();
   }
 }
 
 
 // RENDER VIEW LAYOUT MANAGER
 
 class ViewConstraints {
@@ skipping 94 matching lines @@
 
   void defaultPaint(RenderNodeDisplayList canvas) {
     RenderBox child = firstChild;
     while (child != null) {
       assert(child.parentData is ParentDataType);
       canvas.paintChild(child, child.parentData.position);
       child = child.parentData.nextSibling;
     }
   }
 }