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_DEC_H_ 16 #define WEBP_DEC_VP8LI_DEC_H_ 17 18 #include <string.h> // for memcpy() 19 #include "src/dec/webpi_dec.h" 20 #include "src/utils/bit_reader_utils.h" 21 #include "src/utils/color_cache_utils.h" 22 #include "src/utils/huffman_utils.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_DEC_H_ 136