third_party/libwebp/dec/vp8li.h

   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
  47   int             huffman_mask_;
  48   int             huffman_subsample_bits_;
  49   int             huffman_xsize_;
  50   uint32_t       *huffman_image_;
  51   int             num_htree_groups_;
  52   HTreeGroup     *htree_groups_;
  53 } VP8LMetadata;
  54
  55 typedef struct VP8LDecoder VP8LDecoder;
  56 struct VP8LDecoder {
  57   VP8StatusCode    status_;
  58   VP8LDecodeState  action_;
  59   VP8LDecodeState  state_;
  60   VP8Io           *io_;
  61
  62   const WebPDecBuffer *output_;    // shortcut to io->opaque->output
  63
  64   uint32_t        *pixels_;        // Internal data: either uint8_t* for alpha
  65                                    // or uint32_t* for BGRA.
  66   uint32_t        *argb_cache_;    // Scratch buffer for temporary BGRA storage.
  67
  68   VP8LBitReader    br_;
  69
  70   int              width_;
  71   int              height_;
  72   int              last_row_;      // last input row decoded so far.
  73   int              last_pixel_;    // last pixel decoded so far. However, it may
  74                                    // not be transformed, scaled and
  75                                    // color-converted yet.
  76   int              last_out_row_;  // last row output so far.
  77
  78   VP8LMetadata     hdr_;
  79
  80   int              next_transform_;
  81   VP8LTransform    transforms_[NUM_TRANSFORMS];
  82   // or'd bitset storing the transforms types.
  83   uint32_t         transforms_seen_;
  84
  85   uint8_t         *rescaler_memory;  // Working memory for rescaling work.
  86   WebPRescaler    *rescaler;         // Common rescaler for all channels.
  87 };
  88
  89 //------------------------------------------------------------------------------
  90 // internal functions. Not public.
  91
  92 struct ALPHDecoder;  // Defined in dec/alphai.h.
  93
  94 // in vp8l.c
  95
  96 // Decodes image header for alpha data stored using lossless compression.
  97 // Returns false in case of error.
  98 int VP8LDecodeAlphaHeader(struct ALPHDecoder* const alph_dec,
  99                           const uint8_t* const data, size_t data_size,
 100                           uint8_t* const output);
 101
 102 // Decodes *at least* 'last_row' rows of alpha. If some of the initial rows are
 103 // already decoded in previous call(s), it will resume decoding from where it
 104 // was paused.
 105 // Returns false in case of bitstream error.
 106 int VP8LDecodeAlphaImageStream(struct ALPHDecoder* const alph_dec,
 107                                int last_row);
 108
 109 // Allocates and initialize a new lossless decoder instance.
 110 VP8LDecoder* VP8LNew(void);
 111
 112 // Decodes the image header. Returns false in case of error.
 113 int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io);
 114
 115 // Decodes an image. It's required to decode the lossless header before calling
 116 // this function. Returns false in case of error, with updated dec->status_.
 117 int VP8LDecodeImage(VP8LDecoder* const dec);
 118
 119 // Resets the decoder in its initial state, reclaiming memory.
 120 // Preserves the dec->status_ value.
 121 void VP8LClear(VP8LDecoder* const dec);
 122
 123 // Clears and deallocate a lossless decoder instance.
 124 void VP8LDelete(VP8LDecoder* const dec);
 125
 126 //------------------------------------------------------------------------------
 127
 128 #ifdef __cplusplus
 129 }    // extern "C"
 130 #endif
 131
 132 #endif  /* WEBP_DEC_VP8LI_H_ */