godot/thirdparty/libwebp/src/dec/alpha_dec.c

// Copyright 2011 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.
// -----------------------------------------------------------------------------
//
// Alpha-plane decompression.
//
// Author: Skal ([email protected])

#include <stdlib.h>
#include "src/dec/alphai_dec.h"
#include "src/dec/vp8_dec.h"
#include "src/dec/vp8i_dec.h"
#include "src/dec/vp8li_dec.h"
#include "src/dsp/dsp.h"
#include "src/utils/quant_levels_dec_utils.h"
#include "src/utils/utils.h"
#include "src/webp/format_constants.h"
#include "src/webp/types.h"

//------------------------------------------------------------------------------
// ALPHDecoder object.

// Allocates a new alpha decoder instance.
WEBP_NODISCARD static ALPHDecoder* ALPHNew(void) { … }

// Clears and deallocates an alpha decoder instance.
static void ALPHDelete(ALPHDecoder* const dec) { … }

//------------------------------------------------------------------------------
// Decoding.

// Initialize alpha decoding by parsing the alpha header and decoding the image
// header for alpha data stored using lossless compression.
// Returns false in case of error in alpha header (data too short, invalid
// compression method or filter, error in lossless header data etc).
WEBP_NODISCARD static int ALPHInit(ALPHDecoder* const dec, const uint8_t* data,
                                   size_t data_size, const VP8Io* const src_io,
                                   uint8_t* output) { … }

// Decodes, unfilters and dequantizes *at least* 'num_rows' rows of alpha
// starting from row number 'row'. It assumes that rows up to (row - 1) have
// already been decoded.
// Returns false in case of bitstream error.
WEBP_NODISCARD static int ALPHDecode(VP8Decoder* const dec, int row,
                                     int num_rows) { … }

WEBP_NODISCARD static int AllocateAlphaPlane(VP8Decoder* const dec,
                                             const VP8Io* const io) { … }

void WebPDeallocateAlphaMemory(VP8Decoder* const dec) { … }

//------------------------------------------------------------------------------
// Main entry point.

WEBP_NODISCARD const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
                                                     const VP8Io* const io,
                                                     int row, int num_rows) { … }