Implement unit tests and temporary MathUtil wrappers for transform functionality

ui/gfx/transform.cc

 // Copyright (c) 2012 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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/gfx/transform.h"
 
 #include <cmath>
@@ skipping 98 matching lines @@
 
 void Transform::SetSkewX(double angle) {
   MSET(matrix_, 0, 1, TanDegrees(angle));
 }
 
 void Transform::SetSkewY(double angle) {
   MSET(matrix_, 1, 0, TanDegrees(angle));
 }
 
 void Transform::SetPerspectiveDepth(double depth) {
+  if (depth == 0)
+      return;

[Ian Vollick, 2012/11/16 13:44:46]

Good catch. Thank you!

+
   SkMatrix44 m;
   MSET(m, 3, 2, -1.0 / depth);
   matrix_ = m;
 }
 
 void Transform::ConcatRotate(double degree) {
   SkMatrix44 rot;
   rot.setRotateDegreesAbout(SkDoubleToMScalar(0),
                             SkDoubleToMScalar(0),
                             SkDoubleToMScalar(1),
@@ skipping 48 matching lines @@
   matrix_.postConcat(t.matrix_);
 }
 
 void Transform::ConcatSkewY(double angle_y) {
   Transform t;
   t.SetSkewY(angle_y);
   matrix_.postConcat(t.matrix_);
 }
 
 void Transform::ConcatPerspectiveDepth(double depth) {
+  if (depth == 0)
+      return;
+
   SkMatrix44 m;
   MSET(m, 3, 2, -1.0 / depth);
   matrix_.postConcat(m);
 }
 
 void Transform::PreconcatRotate(double degree) {
   SkMatrix44 rot;
   rot.setRotateDegreesAbout(SkDoubleToMScalar(0),
                             SkDoubleToMScalar(0),
                             SkDoubleToMScalar(1),
@@ skipping 48 matching lines @@
   matrix_.preConcat(t.matrix_);
 }
 
 void Transform::PreconcatSkewY(double angle_y) {
   Transform t;
   t.SetSkewY(angle_y);
   matrix_.preConcat(t.matrix_);
 }
 
 void Transform::PreconcatPerspectiveDepth(double depth) {
+  if (depth == 0)
+      return;
+
   SkMatrix44 m;
   MSET(m, 3, 2, -1.0 / depth);
   matrix_.preConcat(m);
 }
 
 void Transform::PreconcatTransform(const Transform& transform) {
   if (!transform.matrix_.isIdentity()) {
     matrix_.preConcat(transform.matrix_);
   }
 }
@@ skipping 106 matching lines @@
     SkDoubleToMScalar(0),
     SkDoubleToMScalar(1)
   };
 
   xform.mapMScalars(p);
 
   point.SetPoint(ToRoundedInt(p[0]), ToRoundedInt(p[1]));
 }
 
 }  // namespace gfx