| 1 | /* |
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| 2 | * Copyright 2015 Google Inc. |
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| 3 | * |
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| 4 | * Use of this source code is governed by a BSD-style license that can be |
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| 5 | * found in the LICENSE file. |
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| 6 | */ |
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| 7 | #ifndef SkSampler_DEFINED |
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| 8 | #define SkSampler_DEFINED |
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| 9 | |
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| 10 | #include "include/codec/SkCodec.h" |
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| 11 | #include "include/core/SkTypes.h" |
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| 12 | #include "include/private/base/SkNoncopyable.h" |
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| 13 | #include "src/codec/SkCodecPriv.h" |
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| 14 | |
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| 15 | #include <cstddef> |
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| 16 | |
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| 17 | struct SkImageInfo; |
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| 18 | |
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| 19 | class SkSampler : public SkNoncopyable { |
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| 20 | public: |
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| 21 | /** |
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| 22 | * Update the sampler to sample every sampleX'th pixel. Returns the |
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| 23 | * width after sampling. |
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| 24 | */ |
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| 25 | int setSampleX(int sampleX) { |
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| 26 | return this->onSetSampleX(sampleX); |
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| 27 | } |
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| 28 | |
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| 29 | /** |
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| 30 | * Update the sampler to sample every sampleY'th row. |
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| 31 | */ |
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| 32 | void setSampleY(int sampleY) { |
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| 33 | fSampleY = sampleY; |
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| 34 | } |
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| 35 | |
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| 36 | /** |
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| 37 | * Retrieve the value set for sampleY. |
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| 38 | */ |
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| 39 | int sampleY() const { |
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| 40 | return fSampleY; |
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| 41 | } |
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| 42 | |
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| 43 | /** |
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| 44 | * Based on fSampleY, return whether this row belongs in the output. |
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| 45 | * |
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| 46 | * @param row Row of the image, starting with the first row in the subset. |
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| 47 | */ |
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| 48 | bool rowNeeded(int row) const { |
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| 49 | return (row - get_start_coord(sampleFactor: fSampleY)) % fSampleY == 0; |
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| 50 | } |
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| 51 | |
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| 52 | /** |
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| 53 | * Fill the remainder of the destination with 0. |
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| 54 | * |
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| 55 | * 0 has a different meaning depending on the SkColorType. For color types |
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| 56 | * with transparency, this means transparent. For k565 and kGray, 0 is |
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| 57 | * black. |
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| 58 | * |
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| 59 | * @param info |
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| 60 | * Contains the color type of the rows to fill. |
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| 61 | * Contains the pixel width of the destination rows to fill |
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| 62 | * Contains the number of rows that we need to fill. |
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| 63 | * |
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| 64 | * @param dst |
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| 65 | * The destination row to fill. |
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| 66 | * |
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| 67 | * @param rowBytes |
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| 68 | * Stride in bytes of the destination. |
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| 69 | * |
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| 70 | * @param zeroInit |
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| 71 | * Indicates whether memory is already zero initialized. |
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| 72 | */ |
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| 73 | static void Fill(const SkImageInfo& info, void* dst, size_t rowBytes, |
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| 74 | SkCodec::ZeroInitialized zeroInit); |
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| 75 | |
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| 76 | virtual int fillWidth() const = 0; |
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| 77 | |
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| 78 | SkSampler() |
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| 79 | : fSampleY(1) |
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| 80 | {} |
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| 81 | |
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| 82 | virtual ~SkSampler() {} |
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| 83 | private: |
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| 84 | int fSampleY; |
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| 85 | |
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| 86 | virtual int onSetSampleX(int) = 0; |
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| 87 | }; |
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| 88 | |
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| 89 | #endif // SkSampler_DEFINED |
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| 90 | |
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