Fixes matrix transformations in sprites

Adds hit tests and transformations between coordinate systems in sprites

Sprite nodes use Point instead of Vector2

Updates sprite test app

Refactors accounting for pivot points in sprites

Adds abstract NodeWithSize class in Sprites.

Refactors SpriteNode to Sprite

Refactors TransformNode to Node (may need to find another name as it conflicts with Sky's Node).

Sprite system now uses and caches transformation matrices.

R=abarth@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/476b7fdc67dc470aafff64cae3c45f989f307730

[viktorl, 2015-06-11 00:05:48]

viktorl@google.com changed reviewers:
+ eseidel@chromium.org

[abarth-chromium, 2015-06-11 00:07:03]

"Sky's Node"  <--- You might want to always import sky with a prefix:

import 'dart:sky' as sky;

Then you won't have any name conflicts.

[abarth-chromium, 2015-06-11 00:20:18]

abarth@chromium.org changed reviewers:
+ abarth@chromium.org

[abarth-chromium, 2015-06-11 00:20:20]

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/game_...
File sky/examples/game/lib/game_tests.dart (right):

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/game_...
sky/examples/game/lib/game_tests.dart:11: Point pointerPos = new Point(event.x,
event.y);
You might want to use entry.localPosition rather than event.x and event.y.  That
will give you a Point in your local coordinate space.

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/game_...
sky/examples/game/lib/game_tests.dart:20: sprt.colorOverlay = new
Color(0x66ff0000);
I think you can just write:

node.colorOverlay = new Color(0x66ff0000);

The analyzer should be smart enough to figure it out.

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/node....
File sky/examples/game/lib/node.dart (right):

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/node....
sky/examples/game/lib/node.dart:37: _position = new Point(0.0, 0.0);
Point.origin

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/node....
sky/examples/game/lib/node.dart:228: List<double> matrix = [0.0, 0.0, 0.0, 0.0,
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0];
?  This looks very strange.  Is this really want you want?

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/node_...
File sky/examples/game/lib/node_with_size.dart (right):

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/node_...
sky/examples/game/lib/node_with_size.dart:9: pivot = new Point(0.0, 0.0);
Size.zero
Point.origin

[abarth-chromium, 2015-06-11 00:20:55]

(Sorry, there were many diffs in this CL and I wasn't sure how detailed a review
you were looking for...)

[abarth-chromium, 2015-06-11 00:29:15]

RSLGTM

[abarth-chromium, 2015-06-11 00:33:15]

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/node....
File sky/examples/game/lib/node.dart (right):

https://codereview.chromium.org/1180703002/diff/1/sky/examples/game/lib/node....
sky/examples/game/lib/node.dart:231: canvas.concat(list32);
canvas.concat(transformMatrix.storage)

[abarth-chromium, 2015-06-11 15:39:08]

lgtm

[viktorl, 2015-06-11 15:44:26]

Committed patchset #1 (id:1) manually as
476b7fdc67dc470aafff64cae3c45f989f307730 (presubmit successful).