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1 /* | 1 /* |
2 * Copyright 2015 Google Inc. | 2 * Copyright 2015 Google Inc. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license that can be | 4 * Use of this source code is governed by a BSD-style license that can be |
5 * found in the LICENSE file. | 5 * found in the LICENSE file. |
6 */ | 6 */ |
7 | 7 |
8 #ifndef SkCodec_DEFINED | 8 #ifndef SkCodec_DEFINED |
9 #define SkCodec_DEFINED | 9 #define SkCodec_DEFINED |
10 | 10 |
11 #include "SkEncodedFormat.h" | 11 #include "SkEncodedFormat.h" |
12 #include "SkImageGenerator.h" | 12 #include "SkImageGenerator.h" |
13 #include "SkImageInfo.h" | 13 #include "SkImageInfo.h" |
| 14 #include "SkScanlineDecoder.h" |
14 #include "SkSize.h" | 15 #include "SkSize.h" |
15 #include "SkStream.h" | 16 #include "SkStream.h" |
16 #include "SkTemplates.h" | 17 #include "SkTemplates.h" |
17 #include "SkTypes.h" | 18 #include "SkTypes.h" |
18 | 19 |
19 class SkData; | 20 class SkData; |
20 | 21 |
21 /** | 22 /** |
22 * Abstraction layer directly on top of an image codec. | 23 * Abstraction layer directly on top of an image codec. |
23 */ | 24 */ |
(...skipping 25 matching lines...) Expand all Loading... |
49 */ | 50 */ |
50 SkISize getScaledDimensions(float desiredScale) const { | 51 SkISize getScaledDimensions(float desiredScale) const { |
51 return this->onGetScaledDimensions(desiredScale); | 52 return this->onGetScaledDimensions(desiredScale); |
52 } | 53 } |
53 | 54 |
54 /** | 55 /** |
55 * Format of the encoded data. | 56 * Format of the encoded data. |
56 */ | 57 */ |
57 SkEncodedFormat getEncodedFormat() const { return this->onGetEncodedFormat()
; } | 58 SkEncodedFormat getEncodedFormat() const { return this->onGetEncodedFormat()
; } |
58 | 59 |
| 60 /** |
| 61 * Return an object which can be used to decode individual scanlines. |
| 62 * |
| 63 * This object is owned by the SkCodec, which will handle its lifetime. The |
| 64 * returned object is only valid until the SkCodec is deleted or the next |
| 65 * call to getScanlineDecoder, whichever comes first. |
| 66 * |
| 67 * Calling a second time will rewind and replace the existing one with a |
| 68 * new one. If the stream cannot be rewound, this will delete the existing |
| 69 * one and return NULL. |
| 70 * |
| 71 * @param dstInfo Info of the destination. If the dimensions do not match |
| 72 * those of getInfo, this implies a scale. |
| 73 * @return New SkScanlineDecoder, or NULL on failure. |
| 74 * |
| 75 * NOTE: If any rows were previously decoded, this requires rewinding the |
| 76 * SkStream. |
| 77 * |
| 78 * NOTE: The scanline decoder is owned by the SkCodec and will delete it |
| 79 * when the SkCodec is deleted. |
| 80 */ |
| 81 SkScanlineDecoder* getScanlineDecoder(const SkImageInfo& dstInfo); |
| 82 |
| 83 /** |
| 84 * Some images may initially report that they have alpha due to the format |
| 85 * of the encoded data, but then never use any colors which have alpha |
| 86 * less than 100%. This function can be called *after* decoding to |
| 87 * determine if such an image truly had alpha. Calling it before decoding |
| 88 * is undefined. |
| 89 * FIXME: see skbug.com/3582. |
| 90 */ |
| 91 bool reallyHasAlpha() const { |
| 92 return this->onReallyHasAlpha(); |
| 93 } |
| 94 |
59 protected: | 95 protected: |
60 SkCodec(const SkImageInfo&, SkStream*); | 96 SkCodec(const SkImageInfo&, SkStream*); |
61 | 97 |
62 /** | 98 /** |
63 * The SkAlphaType is a conservative answer. i.e. it is possible that it | 99 * The SkAlphaType is a conservative answer. i.e. it is possible that it |
64 * initially returns a non-opaque answer, but completing the decode | 100 * initially returns a non-opaque answer, but completing the decode |
65 * reveals that the image is actually opaque. | 101 * reveals that the image is actually opaque. |
66 */ | 102 */ |
67 #ifdef SK_SUPPORT_LEGACY_BOOL_ONGETINFO | 103 #ifdef SK_SUPPORT_LEGACY_BOOL_ONGETINFO |
68 bool onGetInfo(SkImageInfo* info) SK_OVERRIDE { | 104 bool onGetInfo(SkImageInfo* info) SK_OVERRIDE { |
69 *info = fInfo; | 105 *info = fInfo; |
70 return true; | 106 return true; |
71 } | 107 } |
72 #endif | 108 #endif |
73 | 109 |
74 virtual SkISize onGetScaledDimensions(float /* desiredScale */) const { | 110 virtual SkISize onGetScaledDimensions(float /* desiredScale */) const { |
75 // By default, scaling is not supported. | 111 // By default, scaling is not supported. |
76 return fInfo.dimensions(); | 112 return fInfo.dimensions(); |
77 } | 113 } |
78 | 114 |
79 virtual SkEncodedFormat onGetEncodedFormat() const = 0; | 115 virtual SkEncodedFormat onGetEncodedFormat() const = 0; |
80 | 116 |
81 /** | 117 /** |
| 118 * Override if your codec supports scanline decoding. |
| 119 * |
| 120 * No need to call rewindIfNeeded(), which will have already been called |
| 121 * by the base class. |
| 122 * |
| 123 * @param dstInfo Info of the destination. If the dimensions do not match |
| 124 * those of getInfo, this implies a scale. |
| 125 * @return New SkScanlineDecoder on success, NULL otherwise. The SkCodec |
| 126 * will take ownership of the returned scanline decoder. |
| 127 */ |
| 128 virtual SkScanlineDecoder* onGetScanlineDecoder(const SkImageInfo& dstInfo)
{ |
| 129 return NULL; |
| 130 } |
| 131 |
| 132 virtual bool onReallyHasAlpha() const { return false; } |
| 133 |
| 134 /** |
82 * If the stream was previously read, attempt to rewind. | 135 * If the stream was previously read, attempt to rewind. |
83 * @returns: | 136 * @returns: |
84 * true | 137 * true |
85 * - if the stream needed to be rewound, and the rewind | 138 * - if the stream needed to be rewound, and the rewind |
86 * succeeded. | 139 * succeeded. |
87 * - if the stream did not need to be rewound. | 140 * - if the stream did not need to be rewound. |
88 * false | 141 * false |
89 * - if the stream needed to be rewound, and rewind failed. | 142 * - if the stream needed to be rewound, and rewind failed. |
90 * Subclasses MUST call this function before reading the stream (e.g. in | 143 * Subclasses MUST call this function before reading the stream (e.g. in |
91 * onGetPixels). If it returns false, onGetPixels should return | 144 * onGetPixels). If it returns false, onGetPixels should return |
92 * kCouldNotRewind. | 145 * kCouldNotRewind. |
93 */ | 146 */ |
94 bool SK_WARN_UNUSED_RESULT rewindIfNeeded(); | 147 bool SK_WARN_UNUSED_RESULT rewindIfNeeded(); |
95 | 148 |
96 /* | 149 /* |
97 * | 150 * |
98 * Get method for the input stream | 151 * Get method for the input stream |
99 * | 152 * |
100 */ | 153 */ |
101 SkStream* stream() { | 154 SkStream* stream() { |
102 return fStream.get(); | 155 return fStream.get(); |
103 } | 156 } |
104 | 157 |
105 private: | 158 private: |
106 const SkImageInfo fInfo; | 159 const SkImageInfo fInfo; |
107 SkAutoTDelete<SkStream> fStream; | 160 SkAutoTDelete<SkStream> fStream; |
108 bool fNeedsRewind; | 161 bool fNeedsRewind; |
| 162 SkAutoTDelete<SkScanlineDecoder> fScanlineDecoder; |
109 | 163 |
110 typedef SkImageGenerator INHERITED; | 164 typedef SkImageGenerator INHERITED; |
111 }; | 165 }; |
112 #endif // SkCodec_DEFINED | 166 #endif // SkCodec_DEFINED |
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