Mozart: Implement basic input event dispatch with hit testing.

mojo/services/geometry/cpp/geometry_util.cc

 // Copyright 2014 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.
 
 #include "mojo/services/geometry/cpp/geometry_util.h"
 
 #include <string.h>
 
 namespace mojo {
 
 static const float kIdentityMatrix[]{
     1.f, 0.f, 0.f, 0.f,  // comments to prevent
     0.f, 1.f, 0.f, 0.f,  // auto formatter reflow
     0.f, 0.f, 1.f, 0.f,  //
     0.f, 0.f, 0.f, 1.f};
 
 void SetIdentityTransform(Transform* transform) {
   transform->matrix.resize(16u);
   memcpy(transform->matrix.data(), kIdentityMatrix, sizeof(kIdentityMatrix));
 }
 
 void SetTranslationTransform(Transform* transform, float x, float y, float z) {
   SetIdentityTransform(transform);
   transform->matrix[3] = x;
   transform->matrix[7] = y;
   transform->matrix[11] = z;
 }
 
+Point TransformPoint(const Transform& transform, const Point& point) {
+  // TODO(jeffbrown): If w is 0, then the point should be at infinity.
+  // Also, we should perhaps be using PointF here rather than Point.
+  float w = transform.matrix[12] * point.x + transform.matrix[13] * point.y +
+            transform.matrix[15];
+  if (!w)
+    w = 1.f / w;
+
+  Point result;
+  result.x = (transform.matrix[0] * point.x + transform.matrix[1] * point.y +
+              transform.matrix[3]) *
+             w;
+  result.y = (transform.matrix[4] * point.x + transform.matrix[5] * point.y +
+              transform.matrix[7]) *
+             w;
+  return result;
+}
+
 }  // namespace mojo