Mozart: Implement basic input event dispatch with hit testing.

mojo/services/geometry/cpp/geometry_util.cc

Index: mojo/services/geometry/cpp/geometry_util.cc
diff --git a/mojo/services/geometry/cpp/geometry_util.cc b/mojo/services/geometry/cpp/geometry_util.cc
index 570f707a2462db19f7e2cbfeb79c8308e8b5c573..bb9353d1c1826dc13cc169331ba1df1c1b997ae1 100644
--- a/mojo/services/geometry/cpp/geometry_util.cc
+++ b/mojo/services/geometry/cpp/geometry_util.cc
@@ -26,4 +26,19 @@ void SetTranslationTransform(Transform* transform, float x, float y, float z) {
   transform->matrix[11] = z;
 }
 
+Point TransformPoint(const Transform& transform, const Point& point) {
+  Point result;
+  result.x = transform.matrix[0] * point.x + transform.matrix[1] * point.y +
+             transform.matrix[3];
+  result.y = transform.matrix[4] * point.x + transform.matrix[5] * point.y +
+             transform.matrix[7];
+  float z = transform.matrix[12] * point.x + transform.matrix[13] * point.y +

[abarth, 2016/03/09 04:17:37]

We usually call this quantity `w`

+            transform.matrix[15];
+  if (z)
+    z = 1.f / z;

[abarth, 2016/03/09 04:17:37]

If `w` is zero, the Point should be at infinity.  Given that it's a int32, we
should probably use MAX_INT.

[jeffbrown, 2016/03/09 19:38:50]

Well, but which infinity?  This behavior is consistent with Skia's
interpretation.  I'll leave a TODO to revisit.

Actually that points out another problem with potential loss of precision in
this code due to the use of integer points.  Need to think about whether that's
the right thing for the compositor to be dealing with.  I probably want to be
using PointF and RectF.

+  result.x *= z;
+  result.y *= z;
+  return result;
+}
+
 }  // namespace mojo