1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef SkPageFlipper_DEFINED 18 #define SkPageFlipper_DEFINED 19 20 #include "SkRegion.h" 21 22 /** SkPageFlipper manages alternating inval/dirty regions for a rectangular area 23 (like a bitmap). You call inval() to accumulate inval areas, and then when 24 you're ready to "flip" pages (i.e. draw into the one you've been 25 invalidating) you call update, which swaps the inval regions, and returns 26 two things to you: 1) the final inval region to be drawn into, and 2) the 27 region of pixels that should be copied from the "front" page onto the one 28 you're about to draw into. This copyBits region will be disjoint from the 29 inval region, so both need to be handled. 30 */ 31 class SkPageFlipper { 32 public: 33 SkPageFlipper(); 34 SkPageFlipper(int width, int height); 35 36 int width() const { return fWidth; } 37 int height() const { return fHeight; } 38 39 void resize(int width, int height); 40 41 bool isDirty() const { return !fDirty1->isEmpty(); } 42 const SkRegion& dirtyRgn() const { return *fDirty1; } 43 44 void inval(); 45 void inval(const SkIRect&); 46 void inval(const SkRegion&); 47 void inval(const SkRect&, bool antialias); 48 49 /** When you're ready to write to the back page, call update. The returned 50 region is the invalidate are that needs to be drawn to. The copyBits 51 region (provided by the caller) is the area that should be copied from 52 the front page to the back page (will not intersect with the returned 53 inval region. 54 55 Once this is called, the two internal regions are swapped, so the *new* 56 back inval region is ready to receive new inval calls. 57 */ 58 const SkRegion& update(SkRegion* copyBits); 59 60 private: 61 SkRegion* fDirty0; 62 SkRegion* fDirty1; 63 SkRegion fDirty0Storage; 64 SkRegion fDirty1Storage; 65 int fWidth; 66 int fHeight; 67 }; 68 69 #endif 70 71
