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 "../private/SkTemplates.h" | 11 #include "../private/SkTemplates.h" |
12 #include "SkColor.h" | 12 #include "SkColor.h" |
13 #include "SkEncodedFormat.h" | 13 #include "SkEncodedFormat.h" |
14 #include "SkImageInfo.h" | 14 #include "SkImageInfo.h" |
15 #include "SkSize.h" | 15 #include "SkSize.h" |
16 #include "SkStream.h" | 16 #include "SkStream.h" |
17 #include "SkTypes.h" | 17 #include "SkTypes.h" |
18 | 18 |
19 class SkData; | 19 class SkData; |
20 class SkPngChunkReader; | 20 class SkPngChunkReader; |
21 class SkSampler; | 21 class SkSampler; |
22 | 22 |
23 /** | 23 /** |
24 * Abstraction layer directly on top of an image codec. | 24 * Abstraction layer directly on top of an image codec. |
25 */ | 25 */ |
26 class SkCodec : SkNoncopyable { | 26 class SkCodec : SkNoncopyable { |
27 public: | 27 public: |
28 /** | 28 /** |
| 29 * Minimum number of bytes that must be buffered in SkStream input. |
| 30 * |
| 31 * An SkStream passed to NewFromStream must be able to use this many |
| 32 * bytes to determine the image type. Then the same SkStream must be |
| 33 * passed to the correct decoder to read from the beginning. |
| 34 * |
| 35 * This can be accomplished by implementing peek() to support peeking |
| 36 * this many bytes, or by implementing rewind() to be able to rewind() |
| 37 * after reading this many bytes. |
| 38 */ |
| 39 static size_t MinBufferedBytesNeeded(); |
| 40 |
| 41 /** |
29 * If this stream represents an encoded image that we know how to decode, | 42 * If this stream represents an encoded image that we know how to decode, |
30 * return an SkCodec that can decode it. Otherwise return NULL. | 43 * return an SkCodec that can decode it. Otherwise return NULL. |
31 * | 44 * |
| 45 * As stated above, this call must be able to peek or read |
| 46 * MinBufferedBytesNeeded to determine the correct format, and then start |
| 47 * reading from the beginning. First it will attempt to peek, and it |
| 48 * assumes that if less than MinBufferedBytesNeeded bytes (but more than |
| 49 * zero) are returned, this is because the stream is shorter than this, |
| 50 * so falling back to reading would not provide more data. If peek() |
| 51 * returns zero bytes, this call will instead attempt to read(). This |
| 52 * will require that the stream can be rewind()ed. |
| 53 * |
| 54 * If SkPngChunkReader is not NULL, take a ref and pass it to libpng if |
| 55 * the image is a png. |
| 56 * |
32 * If the SkPngChunkReader is not NULL then: | 57 * If the SkPngChunkReader is not NULL then: |
33 * If the image is not a PNG, the SkPngChunkReader will be ignored. | 58 * If the image is not a PNG, the SkPngChunkReader will be ignored. |
34 * If the image is a PNG, the SkPngChunkReader will be reffed. | 59 * If the image is a PNG, the SkPngChunkReader will be reffed. |
35 * If the PNG has unknown chunks, the SkPngChunkReader will be used | 60 * If the PNG has unknown chunks, the SkPngChunkReader will be used |
36 * to handle these chunks. SkPngChunkReader will be called to read | 61 * to handle these chunks. SkPngChunkReader will be called to read |
37 * any unknown chunk at any point during the creation of the codec | 62 * any unknown chunk at any point during the creation of the codec |
38 * or the decode. Note that if SkPngChunkReader fails to read a | 63 * or the decode. Note that if SkPngChunkReader fails to read a |
39 * chunk, this could result in a failure to create the codec or a | 64 * chunk, this could result in a failure to create the codec or a |
40 * failure to decode the image. | 65 * failure to decode the image. |
41 * If the PNG does not contain unknown chunks, the SkPngChunkReader | 66 * If the PNG does not contain unknown chunks, the SkPngChunkReader |
(...skipping 574 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
616 * not affect ownership. | 641 * not affect ownership. |
617 * | 642 * |
618 * Only valid during scanline decoding. | 643 * Only valid during scanline decoding. |
619 */ | 644 */ |
620 virtual SkSampler* getSampler(bool /*createIfNecessary*/) { return nullptr;
} | 645 virtual SkSampler* getSampler(bool /*createIfNecessary*/) { return nullptr;
} |
621 | 646 |
622 friend class SkSampledCodec; | 647 friend class SkSampledCodec; |
623 friend class SkIcoCodec; | 648 friend class SkIcoCodec; |
624 }; | 649 }; |
625 #endif // SkCodec_DEFINED | 650 #endif // SkCodec_DEFINED |
OLD | NEW |