Canvas refactoring Phase 4a:

Move Save, SaveLayerAlpha and Restore onto gfx::Canvas.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/2846035

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51179 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 44 insertions, 0 deletions

diff --git a/gfx/canvas.h b/gfx/canvas.h
index d66db03..90495cd 100644
--- a/gfx/canvas.h
+++ b/gfx/canvas.h
@@ -66,6 +66,21 @@ class Canvas {
   // Creates a canvas with the specified size.
   static Canvas* CreateCanvas(int width, int height, bool is_opaque);
 
+  // Saves a copy of the drawing state onto a stack, operating on this copy
+  // until a balanced call to Restore() is made.
+  virtual void Save() = 0;
+
+  // As with Save(), except draws to a layer that is blended with the canvas
+  // at the specified alpha once Restore() is called.
+  // |layer_bounds| are the bounds of the layer relative to the current
+  // transform.
+  virtual void SaveLayerAlpha(U8CPU alpha) = 0;
+  virtual void SaveLayerAlpha(U8CPU alpha, const gfx::Rect& layer_bounds) = 0;
+
+  // Restores the drawing state after a call to Save*(). It is an error to
+  // call Restore() more times than Save*().
+  virtual void Restore() = 0;
+
   // Retrieves the clip rectangle and sets it in the specified rectangle if any.
   // Returns true if the clip rect is non-empty.
   virtual bool GetClipRect(gfx::Rect* clip_rect) = 0;
diff --git a/gfx/canvas_skia.cc b/gfx/canvas_skia.cc
index 8fb752de..28a3596 100644
--- a/gfx/canvas_skia.cc
+++ b/gfx/canvas_skia.cc
@@ -29,6 +29,31 @@ SkBitmap CanvasSkia::ExtractBitmap() const {
   return result;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// CanvasSkia, Canvas implementation:
+
+void CanvasSkia::Save() {
+  save();
+}
+
+void CanvasSkia::SaveLayerAlpha(U8CPU alpha) {
+  saveLayerAlpha(NULL, alpha);
+}
+
+
+void CanvasSkia::SaveLayerAlpha(U8CPU alpha, const gfx::Rect& layer_bounds) {
+  SkRect bounds;
+  bounds.set(SkIntToScalar(layer_bounds.x()),
+             SkIntToScalar(layer_bounds.y()),
+             SkIntToScalar(layer_bounds.right()),
+             SkIntToScalar(layer_bounds.bottom()));
+  saveLayerAlpha(&bounds, alpha);
+}
+
+void CanvasSkia::Restore() {
+  restore();
+}
+
 bool CanvasSkia::GetClipRect(gfx::Rect* r) {
   SkRect clip;
   if (!getClipBounds(&clip)) {
diff --git a/gfx/canvas_skia.h b/gfx/canvas_skia.h
index cae4ac1..1648cbe 100644
--- a/gfx/canvas_skia.h
+++ b/gfx/canvas_skia.h
@@ -80,6 +80,10 @@ class CanvasSkia : public skia::PlatformCanvas,
   SkBitmap ExtractBitmap() const;
 
   // Overridden from Canvas2:
+  virtual void Save();
+  virtual void SaveLayerAlpha(U8CPU alpha);
+  virtual void SaveLayerAlpha(U8CPU alpha, const gfx::Rect& layer_bounds);
+  virtual void Restore();
   virtual bool GetClipRect(gfx::Rect* clip_rect);
   virtual bool ClipRectInt(int x, int y, int w, int h);
   virtual bool IntersectsClipRectInt(int x, int y, int w, int h);