1 2 /* 3 * Copyright 2008 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #ifndef SkPageFlipper_DEFINED 11 #define SkPageFlipper_DEFINED 12 13 #include "SkRegion.h" 14 15 /** SkPageFlipper manages alternating inval/dirty regions for a rectangular area 16 (like a bitmap). You call inval() to accumulate inval areas, and then when 17 you're ready to "flip" pages (i.e. draw into the one you've been 18 invalidating) you call update, which swaps the inval regions, and returns 19 two things to you: 1) the final inval region to be drawn into, and 2) the 20 region of pixels that should be copied from the "front" page onto the one 21 you're about to draw into. This copyBits region will be disjoint from the 22 inval region, so both need to be handled. 23 */ 24 class SkPageFlipper { 25 public: 26 SkPageFlipper(); 27 SkPageFlipper(int width, int height); 28 29 int width() const { return fWidth; } 30 int height() const { return fHeight; } 31 32 void resize(int width, int height); 33 34 bool isDirty() const { return !fDirty1->isEmpty(); } 35 const SkRegion& dirtyRgn() const { return *fDirty1; } 36 37 void inval(); 38 void inval(const SkIRect&); 39 void inval(const SkRegion&); 40 void inval(const SkRect&, bool antialias); 41 42 /** When you're ready to write to the back page, call update. The returned 43 region is the invalidate are that needs to be drawn to. The copyBits 44 region (provided by the caller) is the area that should be copied from 45 the front page to the back page (will not intersect with the returned 46 inval region. 47 48 Once this is called, the two internal regions are swapped, so the *new* 49 back inval region is ready to receive new inval calls. 50 */ 51 const SkRegion& update(SkRegion* copyBits); 52 53 private: 54 SkRegion* fDirty0; 55 SkRegion* fDirty1; 56 SkRegion fDirty0Storage; 57 SkRegion fDirty1Storage; 58 int fWidth; 59 int fHeight; 60 }; 61 62 #endif 63
