-Added ability to convert xml and tscn scenes to binary on export, makes loading of larger scenes faster
167 lines
5.5 KiB
C
167 lines
5.5 KiB
C
// Copyright 2011 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Alpha-plane decompression.
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#include <stdlib.h>
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#include "./alphai.h"
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#include "./vp8i.h"
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#include "./vp8li.h"
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#include "../dsp/dsp.h"
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#include "../utils/quant_levels_dec.h"
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#include "../utils/utils.h"
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#include "../webp/format_constants.h"
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//------------------------------------------------------------------------------
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// ALPHDecoder object.
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ALPHDecoder* ALPHNew(void) {
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ALPHDecoder* const dec = (ALPHDecoder*)WebPSafeCalloc(1ULL, sizeof(*dec));
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return dec;
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}
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void ALPHDelete(ALPHDecoder* const dec) {
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if (dec != NULL) {
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VP8LDelete(dec->vp8l_dec_);
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dec->vp8l_dec_ = NULL;
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WebPSafeFree(dec);
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}
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}
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//------------------------------------------------------------------------------
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// Decoding.
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// Initialize alpha decoding by parsing the alpha header and decoding the image
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// header for alpha data stored using lossless compression.
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// Returns false in case of error in alpha header (data too short, invalid
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// compression method or filter, error in lossless header data etc).
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static int ALPHInit(ALPHDecoder* const dec, const uint8_t* data,
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size_t data_size, int width, int height, uint8_t* output) {
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int ok = 0;
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const uint8_t* const alpha_data = data + ALPHA_HEADER_LEN;
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const size_t alpha_data_size = data_size - ALPHA_HEADER_LEN;
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int rsrv;
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assert(width > 0 && height > 0);
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assert(data != NULL && output != NULL);
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dec->width_ = width;
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dec->height_ = height;
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if (data_size <= ALPHA_HEADER_LEN) {
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return 0;
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}
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dec->method_ = (data[0] >> 0) & 0x03;
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dec->filter_ = (data[0] >> 2) & 0x03;
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dec->pre_processing_ = (data[0] >> 4) & 0x03;
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rsrv = (data[0] >> 6) & 0x03;
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if (dec->method_ < ALPHA_NO_COMPRESSION ||
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dec->method_ > ALPHA_LOSSLESS_COMPRESSION ||
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dec->filter_ >= WEBP_FILTER_LAST ||
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dec->pre_processing_ > ALPHA_PREPROCESSED_LEVELS ||
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rsrv != 0) {
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return 0;
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}
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if (dec->method_ == ALPHA_NO_COMPRESSION) {
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const size_t alpha_decoded_size = dec->width_ * dec->height_;
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ok = (alpha_data_size >= alpha_decoded_size);
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} else {
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assert(dec->method_ == ALPHA_LOSSLESS_COMPRESSION);
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ok = VP8LDecodeAlphaHeader(dec, alpha_data, alpha_data_size, output);
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}
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VP8FiltersInit();
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return ok;
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}
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// Decodes, unfilters and dequantizes *at least* 'num_rows' rows of alpha
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// starting from row number 'row'. It assumes that rows up to (row - 1) have
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// already been decoded.
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// Returns false in case of bitstream error.
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static int ALPHDecode(VP8Decoder* const dec, int row, int num_rows) {
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ALPHDecoder* const alph_dec = dec->alph_dec_;
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const int width = alph_dec->width_;
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const int height = alph_dec->height_;
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WebPUnfilterFunc unfilter_func = WebPUnfilters[alph_dec->filter_];
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uint8_t* const output = dec->alpha_plane_;
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if (alph_dec->method_ == ALPHA_NO_COMPRESSION) {
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const size_t offset = row * width;
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const size_t num_pixels = num_rows * width;
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assert(dec->alpha_data_size_ >= ALPHA_HEADER_LEN + offset + num_pixels);
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memcpy(dec->alpha_plane_ + offset,
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dec->alpha_data_ + ALPHA_HEADER_LEN + offset, num_pixels);
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} else { // alph_dec->method_ == ALPHA_LOSSLESS_COMPRESSION
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assert(alph_dec->vp8l_dec_ != NULL);
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if (!VP8LDecodeAlphaImageStream(alph_dec, row + num_rows)) {
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return 0;
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}
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}
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if (unfilter_func != NULL) {
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unfilter_func(width, height, width, row, num_rows, output);
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}
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if (row + num_rows == dec->pic_hdr_.height_) {
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dec->is_alpha_decoded_ = 1;
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}
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return 1;
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}
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//------------------------------------------------------------------------------
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// Main entry point.
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const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
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int row, int num_rows) {
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const int width = dec->pic_hdr_.width_;
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const int height = dec->pic_hdr_.height_;
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if (row < 0 || num_rows <= 0 || row + num_rows > height) {
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return NULL; // sanity check.
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}
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if (row == 0) {
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// Initialize decoding.
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assert(dec->alpha_plane_ != NULL);
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dec->alph_dec_ = ALPHNew();
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if (dec->alph_dec_ == NULL) return NULL;
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if (!ALPHInit(dec->alph_dec_, dec->alpha_data_, dec->alpha_data_size_,
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width, height, dec->alpha_plane_)) {
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ALPHDelete(dec->alph_dec_);
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dec->alph_dec_ = NULL;
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return NULL;
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}
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// if we allowed use of alpha dithering, check whether it's needed at all
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if (dec->alph_dec_->pre_processing_ != ALPHA_PREPROCESSED_LEVELS) {
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dec->alpha_dithering_ = 0; // disable dithering
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} else {
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num_rows = height; // decode everything in one pass
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}
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}
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if (!dec->is_alpha_decoded_) {
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int ok = 0;
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assert(dec->alph_dec_ != NULL);
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ok = ALPHDecode(dec, row, num_rows);
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if (ok && dec->alpha_dithering_ > 0) {
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ok = WebPDequantizeLevels(dec->alpha_plane_, width, height,
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dec->alpha_dithering_);
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}
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if (!ok || dec->is_alpha_decoded_) {
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ALPHDelete(dec->alph_dec_);
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dec->alph_dec_ = NULL;
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}
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if (!ok) return NULL; // Error.
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}
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// Return a pointer to the current decoded row.
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return dec->alpha_plane_ + row * width;
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}
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