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| 1 // Copyright 2012 Google Inc. All Rights Reserved. | |
| 2 // | |
| 3 // Use of this source code is governed by a BSD-style license | |
| 4 // that can be found in the COPYING file in the root of the source | |
| 5 // tree. An additional intellectual property rights grant can be found | |
| 6 // in the file PATENTS. All contributing project authors may | |
| 7 // be found in the AUTHORS file in the root of the source tree. | |
| 8 // ----------------------------------------------------------------------------- | |
| 9 // | |
| 10 // Lossless decoder: internal header. | |
| 11 // | |
| 12 // Author: Skal (pascal.massimino@gmail.com) | |
| 13 // Vikas Arora(vikaas.arora@gmail.com) | |
| 14 | |
| 15 #ifndef WEBP_DEC_VP8LI_H_ | |
| 16 #define WEBP_DEC_VP8LI_H_ | |
| 17 | |
| 18 #include <string.h> // for memcpy() | |
| 19 #include "./webpi.h" | |
| 20 #include "../utils/bit_reader.h" | |
| 21 #include "../utils/color_cache.h" | |
| 22 #include "../utils/huffman.h" | |
| 23 | |
| 24 #ifdef __cplusplus | |
| 25 extern "C" { | |
| 26 #endif | |
| 27 | |
| 28 typedef enum { | |
| 29 READ_DATA = 0, | |
| 30 READ_HDR = 1, | |
| 31 READ_DIM = 2 | |
| 32 } VP8LDecodeState; | |
| 33 | |
| 34 typedef struct VP8LTransform VP8LTransform; | |
| 35 struct VP8LTransform { | |
| 36 VP8LImageTransformType type_; // transform type. | |
| 37 int bits_; // subsampling bits defining transform window. | |
| 38 int xsize_; // transform window X index. | |
| 39 int ysize_; // transform window Y index. | |
| 40 uint32_t *data_; // transform data. | |
| 41 }; | |
| 42 | |
| 43 typedef struct { | |
| 44 int color_cache_size_; | |
| 45 VP8LColorCache color_cache_; | |
| 46 VP8LColorCache saved_color_cache_; // for incremental | |
| 47 | |
| 48 int huffman_mask_; | |
| 49 int huffman_subsample_bits_; | |
| 50 int huffman_xsize_; | |
| 51 uint32_t *huffman_image_; | |
| 52 int num_htree_groups_; | |
| 53 HTreeGroup *htree_groups_; | |
| 54 HuffmanCode *huffman_tables_; | |
| 55 } VP8LMetadata; | |
| 56 | |
| 57 typedef struct VP8LDecoder VP8LDecoder; | |
| 58 struct VP8LDecoder { | |
| 59 VP8StatusCode status_; | |
| 60 VP8LDecodeState state_; | |
| 61 VP8Io *io_; | |
| 62 | |
| 63 const WebPDecBuffer *output_; // shortcut to io->opaque->output | |
| 64 | |
| 65 uint32_t *pixels_; // Internal data: either uint8_t* for alpha | |
| 66 // or uint32_t* for BGRA. | |
| 67 uint32_t *argb_cache_; // Scratch buffer for temporary BGRA storage. | |
| 68 | |
| 69 VP8LBitReader br_; | |
| 70 int incremental_; // if true, incremental decoding is expected | |
| 71 VP8LBitReader saved_br_; // note: could be local variables too | |
| 72 int saved_last_pixel_; | |
| 73 | |
| 74 int width_; | |
| 75 int height_; | |
| 76 int last_row_; // last input row decoded so far. | |
| 77 int last_pixel_; // last pixel decoded so far. However, it may | |
| 78 // not be transformed, scaled and | |
| 79 // color-converted yet. | |
| 80 int last_out_row_; // last row output so far. | |
| 81 | |
| 82 VP8LMetadata hdr_; | |
| 83 | |
| 84 int next_transform_; | |
| 85 VP8LTransform transforms_[NUM_TRANSFORMS]; | |
| 86 // or'd bitset storing the transforms types. | |
| 87 uint32_t transforms_seen_; | |
| 88 | |
| 89 uint8_t *rescaler_memory; // Working memory for rescaling work. | |
| 90 WebPRescaler *rescaler; // Common rescaler for all channels. | |
| 91 }; | |
| 92 | |
| 93 //------------------------------------------------------------------------------ | |
| 94 // internal functions. Not public. | |
| 95 | |
| 96 struct ALPHDecoder; // Defined in dec/alphai.h. | |
| 97 | |
| 98 // in vp8l.c | |
| 99 | |
| 100 // Decodes image header for alpha data stored using lossless compression. | |
| 101 // Returns false in case of error. | |
| 102 int VP8LDecodeAlphaHeader(struct ALPHDecoder* const alph_dec, | |
| 103 const uint8_t* const data, size_t data_size); | |
| 104 | |
| 105 // Decodes *at least* 'last_row' rows of alpha. If some of the initial rows are | |
| 106 // already decoded in previous call(s), it will resume decoding from where it | |
| 107 // was paused. | |
| 108 // Returns false in case of bitstream error. | |
| 109 int VP8LDecodeAlphaImageStream(struct ALPHDecoder* const alph_dec, | |
| 110 int last_row); | |
| 111 | |
| 112 // Allocates and initialize a new lossless decoder instance. | |
| 113 VP8LDecoder* VP8LNew(void); | |
| 114 | |
| 115 // Decodes the image header. Returns false in case of error. | |
| 116 int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io); | |
| 117 | |
| 118 // Decodes an image. It's required to decode the lossless header before calling | |
| 119 // this function. Returns false in case of error, with updated dec->status_. | |
| 120 int VP8LDecodeImage(VP8LDecoder* const dec); | |
| 121 | |
| 122 // Resets the decoder in its initial state, reclaiming memory. | |
| 123 // Preserves the dec->status_ value. | |
| 124 void VP8LClear(VP8LDecoder* const dec); | |
| 125 | |
| 126 // Clears and deallocate a lossless decoder instance. | |
| 127 void VP8LDelete(VP8LDecoder* const dec); | |
| 128 | |
| 129 //------------------------------------------------------------------------------ | |
| 130 | |
| 131 #ifdef __cplusplus | |
| 132 } // extern "C" | |
| 133 #endif | |
| 134 | |
| 135 #endif /* WEBP_DEC_VP8LI_H_ */ | |
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Chromium Code Reviews
Issue 2651883004:
libwebp-0.6.0-rc1 (Closed)
