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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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