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| 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 SkScaledCodec_DEFINED |
| 8 #define SkScaledCodec_DEFINED |
| 9 |
| 10 #include "SkCodec.h" |
| 11 #include "SkScanlineDecoder.h" |
| 12 |
| 13 class SkScanlineDecoder; |
| 14 class SkStream; |
| 15 |
| 16 /** |
| 17 * This class implements scaling, by sampling scanlines in the y direction. |
| 18 * x-wise sampling is implemented in the swizzler, when getScanlines() is called
. |
| 19 */ |
| 20 class SkScaledCodec : public SkCodec { |
| 21 public: |
| 22 static SkCodec* NewFromStream(SkStream*); |
| 23 static SkCodec* NewFromData(SkData*); |
| 24 |
| 25 virtual ~SkScaledCodec(); |
| 26 |
| 27 /** |
| 28 * returns whether a destination's dimensions are supported for down samplin
g |
| 29 */ |
| 30 static bool DimensionsSupportedForSampling(const SkImageInfo& srcInfo, |
| 31 const SkImageInfo& dstInfo) { |
| 32 // heights must be equal as no native y sampling is supported |
| 33 if (dstInfo.height() != srcInfo.height()) { |
| 34 return false; |
| 35 } |
| 36 // only support down sampling, dstWidth cannot be larger that srcWidth |
| 37 if(dstInfo.width() > srcInfo.width()) { |
| 38 return false; |
| 39 } |
| 40 return true; |
| 41 } |
| 42 |
| 43 static void ComputeSampleSize(const SkImageInfo& dstInfo, const SkImageInfo&
srcInfo, |
| 44 int* sampleSizeX, int* sampleSizeY); |
| 45 |
| 46 protected: |
| 47 /** |
| 48 * Recommend a set of destination dimensions given a requested scale |
| 49 */ |
| 50 SkISize onGetScaledDimensions(float desiredScale) const override; |
| 51 |
| 52 Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&, SkPMCo
lor*, int*) |
| 53 override; |
| 54 SkEncodedFormat onGetEncodedFormat() const override { |
| 55 return fScanlineDecoder->getEncodedFormat(); |
| 56 } |
| 57 |
| 58 bool onReallyHasAlpha() const override { |
| 59 return fScanlineDecoder->reallyHasAlpha(); |
| 60 } |
| 61 |
| 62 private: |
| 63 |
| 64 SkAutoTDelete<SkScanlineDecoder> fScanlineDecoder; |
| 65 |
| 66 explicit SkScaledCodec(SkScanlineDecoder*); |
| 67 |
| 68 typedef SkCodec INHERITED; |
| 69 }; |
| 70 #endif // SkScaledCodec_DEFINED |
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