michael@0: 
michael@0: /*
michael@0:  * Copyright 2008 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: #ifndef SkPageFlipper_DEFINED
michael@0: #define SkPageFlipper_DEFINED
michael@0: 
michael@0: #include "SkRegion.h"
michael@0: 
michael@0: /** SkPageFlipper manages alternating inval/dirty regions for a rectangular area
michael@0:     (like a bitmap). You call inval() to accumulate inval areas, and then when
michael@0:     you're ready to "flip" pages (i.e. draw into the one you've been
michael@0:     invalidating) you call update, which swaps the inval regions, and returns
michael@0:     two things to you: 1) the final inval region to be drawn into, and 2) the
michael@0:     region of pixels that should be copied from the "front" page onto the one
michael@0:     you're about to draw into. This copyBits region will be disjoint from the
michael@0:     inval region, so both need to be handled.
michael@0:  */
michael@0: class SkPageFlipper {
michael@0: public:
michael@0:     SkPageFlipper();
michael@0:     SkPageFlipper(int width, int height);
michael@0: 
michael@0:     int width() const { return fWidth; }
michael@0:     int height() const { return fHeight; }
michael@0: 
michael@0:     void resize(int width, int height);
michael@0: 
michael@0:     bool isDirty() const { return !fDirty1->isEmpty(); }
michael@0:     const SkRegion& dirtyRgn() const { return *fDirty1; }
michael@0: 
michael@0:     void inval();
michael@0:     void inval(const SkIRect&);
michael@0:     void inval(const SkRegion&);
michael@0:     void inval(const SkRect&, bool antialias);
michael@0: 
michael@0:     /** When you're ready to write to the back page, call update. The returned
michael@0:         region is the invalidate are that needs to be drawn to. The copyBits
michael@0:         region (provided by the caller) is the area that should be copied from
michael@0:         the front page to the back page (will not intersect with the returned
michael@0:         inval region.
michael@0: 
michael@0:         Once this is called, the two internal regions are swapped, so the *new*
michael@0:         back inval region is ready to receive new inval calls.
michael@0:      */
michael@0:     const SkRegion& update(SkRegion* copyBits);
michael@0: 
michael@0: private:
michael@0:     SkRegion*   fDirty0;
michael@0:     SkRegion*   fDirty1;
michael@0:     SkRegion    fDirty0Storage;
michael@0:     SkRegion    fDirty1Storage;
michael@0:     int         fWidth;
michael@0:     int         fHeight;
michael@0: };
michael@0: 
michael@0: #endif