OLD | NEW |
---|---|
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 * Create a new scanline decoder. | |
62 * | |
63 * Create a new object which can be used to decode individual scanlines. | |
64 * | |
65 * @param dstInfo Info of the destination. If the dimensions do not match | |
66 * those of getInfo, this implies a scale. | |
67 * @return New SkScanlineDecoder, or NULL on failure. | |
68 * | |
69 * NOTE: If any rows were previously decoded, this requires rewinding the | |
70 * SkStream. | |
71 * | |
72 * NOTE: The scanline decoder is owned by the SkCodec and will delete it | |
73 * when the SkCodec is deleted. | |
74 */ | |
75 SkScanlineDecoder* getScanlineDecoder(const SkImageInfo& dstInfo); | |
reed1
2015/03/24 15:45:20
1. Create a new scanline decoder
2. The decoder is
scroggo
2015/03/24 16:55:47
I have updated the comment. I think it's more clea
| |
76 | |
77 /** | |
78 * Some images may initially report that they have alpha due to the format | |
79 * of the encoded data, but then never use any colors which have alpha | |
80 * less than 100%. This function can be called *after* decoding to | |
81 * determine if such an image truly had alpha. Calling it before decoding | |
82 * is undefined. | |
83 */ | |
84 bool reallyHasAlpha() const { | |
85 return this->onReallyHasAlpha(); | |
86 } | |
87 | |
59 protected: | 88 protected: |
60 SkCodec(const SkImageInfo&, SkStream*); | 89 SkCodec(const SkImageInfo&, SkStream*); |
61 | 90 |
62 /** | 91 /** |
63 * The SkAlphaType is a conservative answer. i.e. it is possible that it | 92 * The SkAlphaType is a conservative answer. i.e. it is possible that it |
64 * initially returns a non-opaque answer, but completing the decode | 93 * initially returns a non-opaque answer, but completing the decode |
65 * reveals that the image is actually opaque. | 94 * reveals that the image is actually opaque. |
66 */ | 95 */ |
67 #ifdef SK_SUPPORT_LEGACY_BOOL_ONGETINFO | 96 #ifdef SK_SUPPORT_LEGACY_BOOL_ONGETINFO |
68 bool onGetInfo(SkImageInfo* info) SK_OVERRIDE { | 97 bool onGetInfo(SkImageInfo* info) SK_OVERRIDE { |
69 *info = fInfo; | 98 *info = fInfo; |
70 return true; | 99 return true; |
71 } | 100 } |
72 #endif | 101 #endif |
73 | 102 |
74 // Helper for subclasses. | |
75 const SkImageInfo& getOriginalInfo() { return fInfo; } | |
76 | |
77 virtual SkISize onGetScaledDimensions(float /* desiredScale */) const { | 103 virtual SkISize onGetScaledDimensions(float /* desiredScale */) const { |
78 // By default, scaling is not supported. | 104 // By default, scaling is not supported. |
79 return fInfo.dimensions(); | 105 return fInfo.dimensions(); |
80 } | 106 } |
81 | 107 |
82 virtual SkEncodedFormat onGetEncodedFormat() const = 0; | 108 virtual SkEncodedFormat onGetEncodedFormat() const = 0; |
83 | 109 |
84 /** | 110 /** |
111 * Override if your codec supports scanline decoding. | |
112 * | |
113 * No need to call rewindIfNeeded(), which will have already been called | |
114 * by the base class. | |
115 * | |
116 * @param dstInfo Info of the destination. If the dimensions do not match | |
117 * those of getInfo, this implies a scale. | |
118 * @return New SkScanlineDecoder on success, NULL otherwise. The SkCodec | |
119 * will take ownership of the returned scanline decoder. | |
120 */ | |
121 virtual SkScanlineDecoder* onGetScanlineDecoder(const SkImageInfo& dstInfo) { | |
122 return NULL; | |
123 } | |
124 | |
125 virtual bool onReallyHasAlpha() const { return false; } | |
126 | |
127 /** | |
85 * If the stream was previously read, attempt to rewind. | 128 * If the stream was previously read, attempt to rewind. |
86 * @returns: | 129 * @returns: |
87 * true | 130 * true |
88 * - if the stream needed to be rewound, and the rewind | 131 * - if the stream needed to be rewound, and the rewind |
89 * succeeded. | 132 * succeeded. |
90 * - if the stream did not need to be rewound. | 133 * - if the stream did not need to be rewound. |
91 * false | 134 * false |
92 * - if the stream needed to be rewound, and rewind failed. | 135 * - if the stream needed to be rewound, and rewind failed. |
93 * Subclasses MUST call this function before reading the stream (e.g. in | 136 * Subclasses MUST call this function before reading the stream (e.g. in |
94 * onGetPixels). If it returns false, onGetPixels should return | 137 * onGetPixels). If it returns false, onGetPixels should return |
95 * kCouldNotRewind. | 138 * kCouldNotRewind. |
96 */ | 139 */ |
97 bool SK_WARN_UNUSED_RESULT rewindIfNeeded(); | 140 bool SK_WARN_UNUSED_RESULT rewindIfNeeded(); |
98 | 141 |
99 /* | 142 /* |
100 * | 143 * |
101 * Get method for the input stream | 144 * Get method for the input stream |
102 * | 145 * |
103 */ | 146 */ |
104 SkStream* stream() { | 147 SkStream* stream() { |
105 return fStream.get(); | 148 return fStream.get(); |
106 } | 149 } |
107 | 150 |
108 private: | 151 private: |
109 const SkImageInfo fInfo; | 152 const SkImageInfo fInfo; |
110 SkAutoTDelete<SkStream> fStream; | 153 SkAutoTDelete<SkStream> fStream; |
111 bool fNeedsRewind; | 154 bool fNeedsRewind; |
155 SkAutoTDelete<SkScanlineDecoder> fScanlineDecoder; | |
112 | 156 |
113 typedef SkImageGenerator INHERITED; | 157 typedef SkImageGenerator INHERITED; |
114 }; | 158 }; |
115 #endif // SkCodec_DEFINED | 159 #endif // SkCodec_DEFINED |
OLD | NEW |