1 2 /* 3 * Copyright 2011 Google Inc. 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 #ifndef SkScaledBitmapSampler_DEFINED 9 #define SkScaledBitmapSampler_DEFINED 10 11 #include "SkTypes.h" 12 #include "SkColor.h" 13 #include "SkImageDecoder.h" 14 15 class SkBitmap; 16 17 class SkScaledBitmapSampler { 18 public: 19 SkScaledBitmapSampler(int origWidth, int origHeight, int cellSize); 20 scaledWidth()21 int scaledWidth() const { return fScaledWidth; } scaledHeight()22 int scaledHeight() const { return fScaledHeight; } 23 srcY0()24 int srcY0() const { return fY0; } srcDX()25 int srcDX() const { return fDX; } srcDY()26 int srcDY() const { return fDY; } 27 28 enum SrcConfig { 29 kGray, // 1 byte per pixel 30 kIndex, // 1 byte per pixel 31 kRGB, // 3 bytes per pixel 32 kRGBX, // 4 byes per pixel (ignore 4th) 33 kRGBA, // 4 bytes per pixel 34 kRGB_565 // 2 bytes per pixel 35 }; 36 37 struct Options { 38 bool fDither; 39 bool fPremultiplyAlpha; 40 bool fSkipZeros; OptionsOptions41 explicit Options(const SkImageDecoder &dec) 42 : fDither(dec.getDitherImage()) 43 , fPremultiplyAlpha(!dec.getRequireUnpremultipliedColors()) 44 , fSkipZeros(dec.getSkipWritingZeroes()) 45 { } 46 }; 47 48 // Given a dst bitmap (with pixels already allocated) and a src-config, 49 // prepares iterator to process the src colors and write them into dst. 50 // Returns false if the request cannot be fulfulled. 51 bool begin(SkBitmap* dst, SrcConfig sc, const SkImageDecoder& decoder, 52 const SkPMColor* = NULL); 53 bool begin(SkBitmap* dst, SrcConfig sc, const Options& opts, 54 const SkPMColor* = NULL); 55 // call with row of src pixels, for y = 0...scaledHeight-1. 56 // returns true if the row had non-opaque alpha in it 57 bool next(const uint8_t* SK_RESTRICT src); 58 59 // Like next(), but specifies the y value of the source row, so the 60 // rows can come in any order. If the row is not part of the output 61 // sample, it will be skipped. Only sampleInterlaced OR next should 62 // be called for one SkScaledBitmapSampler. 63 bool sampleInterlaced(const uint8_t* SK_RESTRICT src, int srcY); 64 65 typedef bool (*RowProc)(void* SK_RESTRICT dstRow, 66 const uint8_t* SK_RESTRICT src, 67 int width, int deltaSrc, int y, 68 const SkPMColor[]); 69 70 private: 71 int fScaledWidth; 72 int fScaledHeight; 73 74 int fX0; // first X coord to sample 75 int fY0; // first Y coord (scanline) to sample 76 int fDX; // step between X samples 77 int fDY; // step between Y samples 78 79 #ifdef SK_DEBUG 80 // Keep track of whether the caller is using next or sampleInterlaced. 81 // Only one can be used per sampler. 82 enum SampleMode { 83 kUninitialized_SampleMode, 84 kConsecutive_SampleMode, 85 kInterlaced_SampleMode, 86 }; 87 88 SampleMode fSampleMode; 89 #endif 90 91 // setup state 92 char* fDstRow; // points into bitmap's pixels 93 size_t fDstRowBytes; 94 int fCurrY; // used for dithering 95 int fSrcPixelSize; // 1, 3, 4 96 RowProc fRowProc; 97 98 // optional reference to the src colors if the src is a palette model 99 const SkPMColor* fCTable; 100 101 #ifdef SK_DEBUG 102 // Helper class allowing a test to have access to fRowProc. 103 friend class RowProcTester; 104 #endif 105 }; 106 107 #endif 108