De-virtualize SkCanvas save/restore.

include/core/SkCanvas.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCanvas_DEFINED
 #define SkCanvas_DEFINED
 
@@ skipping 360 matching lines @@
         When the balancing call to restore() is made, the previous matrix, clip,
         and drawFilter are restored.
         @param flags The flags govern what portion of the Matrix/Clip/drawFilter
                      state the save (and matching restore) effect. For example,
                      if only kMatrix is specified, then only the matrix state
                      will be pushed and popped. Likewise for the clip if kClip
                      is specified.  However, the drawFilter is always affected
                      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
         the balancing call to restore() is made is that offscreen transfered to
         the canvas (or the previous layer).
         @param bounds (may be null) This rect, if non-null, is used as a hint to
                       limit the size of the offscreen, and thus drawing may be
                       clipped to it, though that clipping is not guaranteed to
                       happen. If exact clipping is desired, use clipRect().
         @param paint (may be null) This is copied, and is applied to the
                      offscreen when restore() is called
         @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
         the balancing call to restore() is made is that offscreen transfered to
         the canvas (or the previous layer).
         @param bounds (may be null) This rect, if non-null, is used as a hint to
                       limit the size of the offscreen, and thus drawing may be
                       clipped to it, though that clipping is not guaranteed to
                       happen. If exact clipping is desired, use clipRect().
         @param alpha  This is applied to the offscreen when restore() is called.
         @param flags  LayerFlags
         @return The value to pass to restoreToCount() to balance this save()
     */
     int saveLayerAlpha(const SkRect* bounds, U8CPU alpha,
                        SaveFlags flags = kARGB_ClipLayer_SaveFlag);
 
     /** This call balances a previous call to save(), and is used to remove all
         modifications to the matrix/clip/drawFilter state since the last save
         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
         a new canvas is 1.
     */
     int getSaveCount() const;
 
     /** Efficient way to pop any calls to save() that happened after the save
         count reached saveCount. It is an error for saveCount to be greater than
         getSaveCount(). To pop all the way back to the initial matrix/clip context
@@ skipping 764 matching lines @@
     GrRenderTarget* internal_private_accessTopLayerRenderTarget();
 
 protected:
     // default impl defers to getDevice()->newSurface(info)
     virtual SkSurface* onNewSurface(const SkImageInfo&);
 
     // default impl defers to its device
     virtual const void* onPeekPixels(SkImageInfo*, size_t* rowBytes);
     virtual void* onAccessTopLayerPixels(SkImageInfo*, size_t* rowBytes);
 
+    // Subclass save/restore notifiers.
+    // Overriders should call the corresponding INHERITED method up the inheritance chain.
+    // willSaveLayer()'s return value may suppress full layer allocation.
+    enum SaveLayerStrategy {
+        kFullLayer_SaveLayerStrategy,
+        kNoLayer_SaveLayerStrategy
+    };
+    virtual void willSave(SaveFlags);
+    virtual SaveLayerStrategy willSaveLayer(const SkRect*, const SkPaint*, SaveFlags);
+    virtual void willRestore();
+
     virtual void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&);
 
     enum ClipEdgeStyle {
         kHard_ClipEdgeStyle,
         kSoft_ClipEdgeStyle
     };
 
     virtual void onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle edgeStyle);
     virtual void onClipRRect(const SkRRect& rrect, SkRegion::Op op, ClipEdgeStyle edgeStyle);
     virtual void onClipPath(const SkPath& path, SkRegion::Op op, ClipEdgeStyle edgeStyle);
@@ skipping 80 matching lines @@
     // internal methods are not virtual, so they can safely be called by other
     // canvas apis, without confusing subclasses (like SkPictureRecording)
     void internalDrawBitmap(const SkBitmap&, const SkMatrix& m, const SkPaint* paint);
     void internalDrawBitmapRect(const SkBitmap& bitmap, const SkRect* src,
                                 const SkRect& dst, const SkPaint* paint,
                                 DrawBitmapRectFlags flags);
     void internalDrawBitmapNine(const SkBitmap& bitmap, const SkIRect& center,
                                 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, SaveLayerStrategy strategy);
     void internalDrawDevice(SkBaseDevice*, int x, int y, const SkPaint*);
 
     // shared by save() and saveLayer()
     int internalSave(SaveFlags flags);
     void internalRestore();
     static void DrawRect(const SkDraw& draw, const SkPaint& paint,
                          const SkRect& r, SkScalar textSize);
     static void DrawTextDecorations(const SkDraw& draw, const SkPaint& paint,
                                     const char text[], size_t byteLength,
                                     SkScalar x, SkScalar y);
@@ skipping 132 matching lines @@
     bool asROBitmap(SkBitmap*) const;
 
 private:
     SkBitmap    fBitmap;    // used if peekPixels() fails
     const void* fAddr;      // NULL on failure
     SkImageInfo fInfo;
     size_t      fRowBytes;
 };
 
 #endif