Use SkMatrix44 for the underlying implementation of ui::Transform

ui/gfx/transform.h

Index: ui/gfx/transform.h
diff --git a/ui/gfx/transform.h b/ui/gfx/transform.h
index 3fdfc3235a36c79eab4508d7481e9c05e8a83278..fe8d37aa88a0b6adb273fe13e877d555a465983a 100644
--- a/ui/gfx/transform.h
+++ b/ui/gfx/transform.h
@@ -8,7 +8,7 @@
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
-#include "third_party/skia/include/core/SkMatrix.h"
+#include "third_party/skia/experimental/SkMatrix44.h"
 
 namespace gfx {
 class Point;
@@ -17,9 +17,8 @@ class Rect;
 
 namespace ui {
 
-// 3x3 transformation matrix. Transform is cheap and explicitly allows
+// 4x4 transformation matrix. Transform is cheap and explicitly allows
 // copy/assign.
-// TODO: make this a 4x4.
 class Transform {
  public:
   Transform();
@@ -57,24 +56,22 @@ class Transform {
   void ConcatTranslate(float x, float y);
 
   // Applies a transformation on the current transformation
-  // (i.e. 'this = this * transform;'). Returns true if the result can be
-  // represented.
-  bool PreconcatTransform(const Transform& transform);
+  // (i.e. 'this = this * transform;').
+  void PreconcatTransform(const Transform& transform);

[rjkroege, 2011/06/10 17:52:14]

why did we lose the boolean prop?

 
   // Applies a transformation on the current transformation
-  // (i.e. 'this = transform * this;'). Returns true if the result can be
-  // represented.
-  bool ConcatTransform(const Transform& transform);
+  // (i.e. 'this = transform * this;').
+  void ConcatTransform(const Transform& transform);
 
   // Does the transformation change anything?
   bool HasChange() const;
 
   // Applies the transformation on the point. Returns true if the point is
   // transformed successfully.
-  bool TransformPoint(gfx::Point* point);
+  void TransformPoint(gfx::Point* point);
 
-  // Applies the reverse transformation on the point. Returns true if the point
-  // is transformed successfully.
+  // Applies the reverse transformation on the point. Returns true if the
+  // transformation can be inverted
   bool TransformPointReverse(gfx::Point* point);
 
   // Applies transformation on the rectangle. Returns true if the rectangle is
@@ -86,10 +83,15 @@ class Transform {
   bool TransformRectReverse(gfx::Rect* rect);
 
   // Returns the underlying matrix.
-  const SkMatrix& matrix() const { return matrix_; }
+  const SkMatrix44& matrix() const { return matrix_; }
 
  private:
-  SkMatrix matrix_;
+  void TransformPointInternal(const SkMatrix44& xform, gfx::Point* point);
+  bool ComputeInverse();
+
+  SkMatrix44 matrix_;
+  SkMatrix44 inverse_;

[rjkroege, 2011/06/10 17:52:14]

time/space overhead of keeping the inverse?

+  bool hasInverse_;
 
   // copy/assign are allowed.
 };