De-virtualize SkCanvas save/restore.

This moves the state management logic into non-virtual SkCanvas methods,
and turns the virtuals into protected notifiers.

R=robertphillips@google.com, reed@google.com

Review URL: https://codereview.chromium.org/194713008

git-svn-id: http://skia.googlecode.com/svn/trunk@13747 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 13 insertions, 5 deletions

diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index 773df89d78..50d319c772 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -358,7 +358,7 @@ public:
                      by calls to save/restore.
         @return The value to pass to restoreToCount() to balance this save()
     */
-    virtual int save(SaveFlags flags = kMatrixClip_SaveFlag);
+    int save(SaveFlags flags = kMatrixClip_SaveFlag);
 
     /** This behaves the same as save(), but in addition it allocates an
         offscreen bitmap. All drawing calls are directed there, and only when
@@ -373,8 +373,8 @@ public:
         @param flags  LayerFlags
         @return The value to pass to restoreToCount() to balance this save()
     */
-    virtual int saveLayer(const SkRect* bounds, const SkPaint* paint,
-                          SaveFlags flags = kARGB_ClipLayer_SaveFlag);
+    int saveLayer(const SkRect* bounds, const SkPaint* paint,
+                  SaveFlags flags = kARGB_ClipLayer_SaveFlag);
 
     /** This behaves the same as save(), but in addition it allocates an
         offscreen bitmap. All drawing calls are directed there, and only when
@@ -396,7 +396,7 @@ public:
         call.
         It is an error to call restore() more times than save() was called.
     */
-    virtual void restore();
+    void restore();
 
     /** Returns the number of matrix/clip states on the SkCanvas' private stack.
         This will equal # save() calls - # restore() calls + 1. The save count on
@@ -1178,6 +1178,14 @@ protected:
     // default impl defers to its device
     virtual const void* onPeekPixels(SkImageInfo*, size_t* rowBytes);
 
+    // Subclass save/restore notifiers. These are called *before* updating the canvas state.
+    // Overriders should call the corresponding INHERITED method up the inheritance chain.
+    // For onSaveLayer(), returning false suppresses full layer allocation (and forces
+    // the base impl to only perform a state save + bounds clip).
+    virtual void onSave(SaveFlags);
+    virtual bool onSaveLayer(const SkRect*, const SkPaint*, SaveFlags);
+    virtual void onRestore();
+
     virtual void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&);
 
     enum ClipEdgeStyle {
@@ -1277,7 +1285,7 @@ private:
                                 const SkRect& dst, const SkPaint* paint);
     void internalDrawPaint(const SkPaint& paint);
     int internalSaveLayer(const SkRect* bounds, const SkPaint* paint,
-                          SaveFlags, bool justForImageFilter);
+                          SaveFlags, bool justForImageFilter, bool skipLayer);
     void internalDrawDevice(SkBaseDevice*, int x, int y, const SkPaint*);
 
     // shared by save() and saveLayer()