[GeometryInterface] add transformPoint(point) function.

third_party/WebKit/Source/core/dom/DOMMatrixReadOnly.cpp

 // 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 "core/dom/DOMMatrix.h"
 #include "core/dom/DOMMatrixInit.h"
+#include "core/dom/DOMPoint.h"
+#include "core/dom/DOMPointInit.h"
 
 namespace blink {
 namespace {
 
 void setDictionaryMembers(DOMMatrixInit& other) {
   if (!other.hasM11())
     other.setM11(other.hasA() ? other.a() : 1);
 
   if (!other.hasM12())
     other.setM12(other.hasB() ? other.b() : 0);
@@ skipping 186 matching lines @@
   flipY->setM22(-this->m22());
   flipY->setM23(-this->m23());
   flipY->setM24(-this->m24());
   return flipY;
 }
 
 DOMMatrix* DOMMatrixReadOnly::inverse() {
   return DOMMatrix::create(this)->invertSelf();
 }
 
+DOMPoint* DOMMatrixReadOnly::transformPoint(DOMPointInit& point) {

[zino, 2016/10/17 15:44:44]

The spec says that "Even if is2D of the current matrix returns true, a 4x4
matrix multiplication will be performed if the z attribute of point is not 0 or
the w attribute of point is not 1."

In other words, we can optimize this as follows:

if (is2D() && point.z() == 0 && point.w() == 1) {
  double x = point.x * m11 + point.y * m12 + m41;
  double y = point.x * m12 + point.y * m22 + m42;
  return DOMPoint::create(x, y, 0, 1);
}

Also, please add some tests for this.

[Hwanseung Lee, 2016/10/17 23:47:30]

Done.

+  double x = point.x() * m11() + point.y() * m21() + point.z() * m31() +
+             point.w() * m41();
+  double y = point.x() * m12() + point.y() * m22() + point.z() * m32() +
+             point.w() * m42();
+  double z = point.x() * m13() + point.y() * m23() + point.z() * m33() +
+             point.w() * m43();
+  double w = point.x() * m14() + point.y() * m24() + point.z() * m34() +
+             point.w() * m44();
+  return DOMPoint::create(x, y, z, w);
+}
+
 DOMFloat32Array* DOMMatrixReadOnly::toFloat32Array() const {
   float array[] = {
       static_cast<float>(m_matrix->m11()), static_cast<float>(m_matrix->m12()),
       static_cast<float>(m_matrix->m13()), static_cast<float>(m_matrix->m14()),
       static_cast<float>(m_matrix->m21()), static_cast<float>(m_matrix->m22()),
       static_cast<float>(m_matrix->m23()), static_cast<float>(m_matrix->m24()),
       static_cast<float>(m_matrix->m31()), static_cast<float>(m_matrix->m32()),
       static_cast<float>(m_matrix->m33()), static_cast<float>(m_matrix->m34()),
       static_cast<float>(m_matrix->m41()), static_cast<float>(m_matrix->m42()),
       static_cast<float>(m_matrix->m43()), static_cast<float>(m_matrix->m44())};
@@ skipping 22 matching lines @@
            << m24() << ", " << m31() << ", " << m32() << ", " << m33() << ", "
            << m34() << ", " << m41() << ", " << m42() << ", " << m43() << ", "
            << m44();
   }
   stream << ")";
 
   return String(stream.str().c_str());
 }
 
 }  // namespace blink