1 /* libs/graphics/sgl/SkAntiRun.h 2 ** 3 ** Copyright 2006, The Android Open Source Project 4 ** 5 ** Licensed under the Apache License, Version 2.0 (the "License"); 6 ** you may not use this file except in compliance with the License. 7 ** You may obtain a copy of the License at 8 ** 9 ** http://www.apache.org/licenses/LICENSE-2.0 10 ** 11 ** Unless required by applicable law or agreed to in writing, software 12 ** distributed under the License is distributed on an "AS IS" BASIS, 13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 ** See the License for the specific language governing permissions and 15 ** limitations under the License. 16 */ 17 18 #ifndef SkAntiRun_DEFINED 19 #define SkAntiRun_DEFINED 20 21 #include "SkBlitter.h" 22 23 class SkAlphaRuns { 24 public: 25 int16_t* fRuns; 26 uint8_t* fAlpha; 27 empty()28 bool empty() const { 29 SkASSERT(fRuns[0] > 0); 30 return fAlpha[0] == 0 && fRuns[fRuns[0]] == 0; 31 } 32 33 void reset(int width); 34 35 /** 36 * Returns the offsetX value that should be passed on the next call, 37 * assuming we're on the same scanline. If the caller is switching 38 * scanlines, then offsetX should be 0 when this is called. 39 */ 40 int add(int x, U8CPU startAlpha, int middleCount, U8CPU stopAlpha, 41 U8CPU maxValue, int offsetX); 42 43 SkDEBUGCODE(void assertValid(int y, int maxStep) const;) 44 SkDEBUGCODE(void dump() const;) 45 46 static void Break(int16_t runs[], uint8_t alpha[], int x, int count); 47 BreakAt(int16_t runs[],uint8_t alpha[],int x)48 static void BreakAt(int16_t runs[], uint8_t alpha[], int x) { 49 while (x > 0) { 50 int n = runs[0]; 51 SkASSERT(n > 0); 52 53 if (x < n) { 54 alpha[x] = alpha[0]; 55 runs[0] = SkToS16(x); 56 runs[x] = SkToS16(n - x); 57 break; 58 } 59 runs += n; 60 alpha += n; 61 x -= n; 62 } 63 } 64 65 private: 66 SkDEBUGCODE(int fWidth;) 67 SkDEBUGCODE(void validate() const;) 68 }; 69 70 #endif 71 72