Flesh out the Painting API a bit.

sky/engine/core/painting/PaintingContext.idl

Index: sky/engine/core/painting/PaintingContext.idl
diff --git a/sky/engine/core/painting/PaintingContext.idl b/sky/engine/core/painting/PaintingContext.idl
index 8eec203b5b9fbde6570dc4004f7244c640b03275..f7c8884668ae8df2439fb515f5cf93080cd361a3 100644
--- a/sky/engine/core/painting/PaintingContext.idl
+++ b/sky/engine/core/painting/PaintingContext.idl
@@ -2,10 +2,28 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// TODO(mpcomplete): Figure out a better SkMatrix/SkRect representation.
 interface PaintingContext {
   readonly attribute double height;
   readonly attribute double width;
 
+  void save();
+  void saveLayer(float[] bounds4 /* optional */, Paint paint /* optional */);
+  void restore();
+
+  void translate(float dx, float dy);
+  void scale(float sx, float sy);

[robertphillips, 2015/05/13 20:22:06]

rotateDegrees ? to leave room for a rotateRadians ?

[Matt Perry, 2015/05/13 20:32:44]

Done.

+  void rotate(float degrees);
+  void skew(float sx, float sy);
+  void concat(float[] matrix9);
+
+  void clipRect(float[] rect4);
+
+  void drawPaint(Paint paint);
+  void drawRect(float[] rect4, Paint paint);
+  void drawOval(float[] rect4, Paint paint);

[robertphillips, 2015/05/13 20:22:06]

What about something like: drawRoundRectXY(float[] rect4, float xRad, float
yRad, Paint paint);
?

[Matt Perry, 2015/05/13 20:32:44]

Sure. I didn't add all the methods from skia right away, but will add more as I
go.

+  // TODO(mpcomplete): SkScalar is a float. Do we really want doubles?
   void drawCircle(double x, double y, double radius, Paint paint);

[reed1, 2015/05/13 20:35:03]

FWIW : SkScalar is currently float, but we are building up the capability to
optionally switch it to double, but that will be a compile option, not a
requirement.

That said, I agree that this header should be consistent, using all floats or
all doubles.

+
   void commit();
 };