Culling API

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 921 matching lines @@
     virtual void beginCommentGroup(const char* description) {
         // do nothing. Subclasses may do something
     }
     virtual void addComment(const char* kywd, const char* value) {
         // do nothing. Subclasses may do something
     }
     virtual void endCommentGroup() {
         // do nothing. Subclasses may do something
     }
 
+    /**
+     *  With this call the client asserts that subsequent draw operations (up to the
+     *  matching popCull()) are fully contained within the given bounding box. The assertion
+     *  is not enforced, but the information might be used to quick-reject command blocks,
+     *  so an incorrect bounding box may result in incomplete rendering.
+     */
+    void pushCull(const SkRect& cullRect) {
+        ++fCullCount;
+        this->onPushCull(cullRect);
+    }
 
+    /**
+     *  Terminates the current culling block, and restores the previous one (if any).
+     */
+    void popCull() {
+        if (fCullCount > 0) {
+            --fCullCount;
+            this->onPopCull();
+        }
+    }
     //////////////////////////////////////////////////////////////////////////
 
     /** Get the current bounder object.
         The bounder's reference count is unchaged.
         @return the canva's bounder (or NULL).
     */
     SkBounder*  getBounder() const { return fBounder; }
 
     /** Set a new bounder (or NULL).
         Pass NULL to clear any previous bounder.
@@ skipping 145 matching lines @@
 
     // Called by child classes that override clipPath and clipRRect to only
     // track fast conservative clip bounds, rather than exact clips.
     bool updateClipConservativelyUsingBounds(const SkRect&, SkRegion::Op,
                                              bool inverseFilled);
 
     // notify our surface (if we have one) that we are about to draw, so it
     // can perform copy-on-write or invalidate any cached images
     void predrawNotify();
 
+    virtual void onPushCull(const SkRect& cullRect);
+    virtual void onPopCull();
+
 private:
     class MCRec;
 
     SkClipStack fClipStack;
     SkDeque     fMCStack;
     // points to top of stack
     MCRec*      fMCRec;
     // the first N recs that can fit here mean we won't call malloc
     uint32_t    fMCRecStorage[32];
 
     SkBounder*  fBounder;
     int         fSaveLayerCount;    // number of successful saveLayer calls
+    int         fCullCount;         // number of active culls
 
     SkMetaData* fMetaData;
 
     SkSurface_Base*  fSurfaceBase;
     SkSurface_Base* getSurfaceBase() const { return fSurfaceBase; }
     void setSurfaceBase(SkSurface_Base* sb) {
         fSurfaceBase = sb;
     }
     friend class SkSurface_Base;
     friend class SkSurface_Gpu;
@@ skipping 181 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