vp8li_dec.h
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// Copyright 2012 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Lossless decoder: internal header.
//
// Author: Skal (pascal.massimino@gmail.com)
// Vikas Arora(vikaas.arora@gmail.com)
#ifndef WEBP_DEC_VP8LI_DEC_H_
#define WEBP_DEC_VP8LI_DEC_H_
#include <string.h> // for memcpy()
#include "src/dec/webpi_dec.h"
#include "src/utils/bit_reader_utils.h"
#include "src/utils/color_cache_utils.h"
#include "src/utils/huffman_utils.h"
#ifdef __cplusplus
extern "C" {
#endif
typedef enum {
READ_DATA = 0,
READ_HDR = 1,
READ_DIM = 2
} VP8LDecodeState;
typedef struct VP8LTransform VP8LTransform;
struct VP8LTransform {
VP8LImageTransformType type_; // transform type.
int bits_; // subsampling bits defining transform window.
int xsize_; // transform window X index.
int ysize_; // transform window Y index.
uint32_t *data_; // transform data.
};
typedef struct {
int color_cache_size_;
VP8LColorCache color_cache_;
VP8LColorCache saved_color_cache_; // for incremental
int huffman_mask_;
int huffman_subsample_bits_;
int huffman_xsize_;
uint32_t *huffman_image_;
int num_htree_groups_;
HTreeGroup *htree_groups_;
HuffmanCode *huffman_tables_;
} VP8LMetadata;
typedef struct VP8LDecoder VP8LDecoder;
struct VP8LDecoder {
VP8StatusCode status_;
VP8LDecodeState state_;
VP8Io *io_;
const WebPDecBuffer *output_; // shortcut to io->opaque->output
uint32_t *pixels_; // Internal data: either uint8_t* for alpha
// or uint32_t* for BGRA.
uint32_t *argb_cache_; // Scratch buffer for temporary BGRA storage.
VP8LBitReader br_;
int incremental_; // if true, incremental decoding is expected
VP8LBitReader saved_br_; // note: could be local variables too
int saved_last_pixel_;
int width_;
int height_;
int last_row_; // last input row decoded so far.
int last_pixel_; // last pixel decoded so far. However, it may
// not be transformed, scaled and
// color-converted yet.
int last_out_row_; // last row output so far.
VP8LMetadata hdr_;
int next_transform_;
VP8LTransform transforms_[NUM_TRANSFORMS];
// or'd bitset storing the transforms types.
uint32_t transforms_seen_;
uint8_t *rescaler_memory; // Working memory for rescaling work.
WebPRescaler *rescaler; // Common rescaler for all channels.
};
//------------------------------------------------------------------------------
// internal functions. Not public.
struct ALPHDecoder; // Defined in dec/alphai.h.
// in vp8l.c
// Decodes image header for alpha data stored using lossless compression.
// Returns false in case of error.
int VP8LDecodeAlphaHeader(struct ALPHDecoder* const alph_dec,
const uint8_t* const data, size_t data_size);
// Decodes *at least* 'last_row' rows of alpha. If some of the initial rows are
// already decoded in previous call(s), it will resume decoding from where it
// was paused.
// Returns false in case of bitstream error.
int VP8LDecodeAlphaImageStream(struct ALPHDecoder* const alph_dec,
int last_row);
// Allocates and initialize a new lossless decoder instance.
VP8LDecoder* VP8LNew(void);
// Decodes the image header. Returns false in case of error.
int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io);
// Decodes an image. It's required to decode the lossless header before calling
// this function. Returns false in case of error, with updated dec->status_.
int VP8LDecodeImage(VP8LDecoder* const dec);
// Resets the decoder in its initial state, reclaiming memory.
// Preserves the dec->status_ value.
void VP8LClear(VP8LDecoder* const dec);
// Clears and deallocate a lossless decoder instance.
void VP8LDelete(VP8LDecoder* const dec);
//------------------------------------------------------------------------------
#ifdef __cplusplus
} // extern "C"
#endif
#endif // WEBP_DEC_VP8LI_DEC_H_