1/* 2 * Copyright 2015 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7#ifndef SkSampler_DEFINED 8#define SkSampler_DEFINED 9 10#include "include/codec/SkCodec.h" 11#include "include/core/SkTypes.h" 12#include "src/codec/SkCodecPriv.h" 13 14class SkSampler : public SkNoncopyable { 15public: 16 /** 17 * Update the sampler to sample every sampleX'th pixel. Returns the 18 * width after sampling. 19 */ 20 int setSampleX(int sampleX) { 21 return this->onSetSampleX(sampleX); 22 } 23 24 /** 25 * Update the sampler to sample every sampleY'th row. 26 */ 27 void setSampleY(int sampleY) { 28 fSampleY = sampleY; 29 } 30 31 /** 32 * Retrieve the value set for sampleY. 33 */ 34 int sampleY() const { 35 return fSampleY; 36 } 37 38 /** 39 * Based on fSampleY, return whether this row belongs in the output. 40 * 41 * @param row Row of the image, starting with the first row in the subset. 42 */ 43 bool rowNeeded(int row) const { 44 return (row - get_start_coord(fSampleY)) % fSampleY == 0; 45 } 46 47 /** 48 * Fill the remainder of the destination with 0. 49 * 50 * 0 has a different meaning depending on the SkColorType. For color types 51 * with transparency, this means transparent. For k565 and kGray, 0 is 52 * black. 53 * 54 * @param info 55 * Contains the color type of the rows to fill. 56 * Contains the pixel width of the destination rows to fill 57 * Contains the number of rows that we need to fill. 58 * 59 * @param dst 60 * The destination row to fill. 61 * 62 * @param rowBytes 63 * Stride in bytes of the destination. 64 * 65 * @param zeroInit 66 * Indicates whether memory is already zero initialized. 67 */ 68 static void Fill(const SkImageInfo& info, void* dst, size_t rowBytes, 69 SkCodec::ZeroInitialized zeroInit); 70 71 virtual int fillWidth() const = 0; 72 73 SkSampler() 74 : fSampleY(1) 75 {} 76 77 virtual ~SkSampler() {} 78private: 79 int fSampleY; 80 81 virtual int onSetSampleX(int) = 0; 82}; 83 84#endif // SkSampler_DEFINED 85