GRAPHICS: Convert JPEG to the ImageDecoder API
This commit is contained in:
Matthew Hoops
Johannes Schickel
parent
4516b5ea24
commit
765a870445
9 changed files with 96 additions and 108 deletions
787
graphics/decoders/jpeg.cpp
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787
graphics/decoders/jpeg.cpp
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/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include "graphics/conversion.h"
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#include "graphics/pixelformat.h"
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#include "graphics/decoders/jpeg.h"
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#include "common/debug.h"
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#include "common/endian.h"
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#include "common/stream.h"
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#include "common/textconsole.h"
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namespace Graphics {
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// Order used to traverse the quantization tables
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static const uint8 _zigZagOrder[64] = {
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0, 1, 8, 16, 9, 2, 3, 10,
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17, 24, 32, 25, 18, 11, 4, 5,
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12, 19, 26, 33, 40, 48, 41, 34,
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27, 20, 13, 6, 7, 14, 21, 28,
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35, 42, 49, 56, 57, 50, 43, 36,
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29, 22, 15, 23, 30, 37, 44, 51,
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58, 59, 52, 45, 38, 31, 39, 46,
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53, 60, 61, 54, 47, 55, 62, 63
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};
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JPEGDecoder::JPEGDecoder() : ImageDecoder(),
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_stream(NULL), _w(0), _h(0), _numComp(0), _components(NULL), _numScanComp(0),
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_scanComp(NULL), _currentComp(NULL), _rgbSurface(0) {
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// Initialize the quantization tables
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for (int i = 0; i < JPEG_MAX_QUANT_TABLES; i++)
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_quant[i] = NULL;
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// Initialize the Huffman tables
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for (int i = 0; i < 2 * JPEG_MAX_HUFF_TABLES; i++) {
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_huff[i].count = 0;
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_huff[i].values = NULL;
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_huff[i].sizes = NULL;
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_huff[i].codes = NULL;
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}
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}
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JPEGDecoder::~JPEGDecoder() {
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destroy();
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}
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const Surface *JPEGDecoder::getSurface() const {
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// Make sure we have loaded data
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if (!isLoaded())
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return 0;
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if (_rgbSurface)
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return _rgbSurface;
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// Create an RGBA8888 surface
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_rgbSurface = new Graphics::Surface();
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_rgbSurface->create(_w, _h, Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0));
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// Get our component surfaces
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const Graphics::Surface *yComponent = getComponent(1);
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const Graphics::Surface *uComponent = getComponent(2);
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const Graphics::Surface *vComponent = getComponent(3);
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for (uint16 i = 0; i < _h; i++) {
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for (uint16 j = 0; j < _w; j++) {
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byte r = 0, g = 0, b = 0;
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YUV2RGB(*((const byte *)yComponent->getBasePtr(j, i)), *((const byte *)uComponent->getBasePtr(j, i)), *((const byte *)vComponent->getBasePtr(j, i)), r, g, b);
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*((uint32 *)_rgbSurface->getBasePtr(j, i)) = _rgbSurface->format.RGBToColor(r, g, b);
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}
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}
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return _rgbSurface;
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}
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void JPEGDecoder::destroy() {
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// Reset member variables
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_stream = NULL;
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_w = _h = 0;
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_restartInterval = 0;
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// Free the components
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for (int c = 0; c < _numComp; c++)
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_components[c].surface.free();
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delete[] _components; _components = NULL;
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_numComp = 0;
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// Free the scan components
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delete[] _scanComp; _scanComp = NULL;
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_numScanComp = 0;
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_currentComp = NULL;
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// Free the quantization tables
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for (int i = 0; i < JPEG_MAX_QUANT_TABLES; i++) {
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delete[] _quant[i];
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_quant[i] = NULL;
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}
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// Free the Huffman tables
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for (int i = 0; i < 2 * JPEG_MAX_HUFF_TABLES; i++) {
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_huff[i].count = 0;
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delete[] _huff[i].values; _huff[i].values = NULL;
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delete[] _huff[i].sizes; _huff[i].sizes = NULL;
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delete[] _huff[i].codes; _huff[i].codes = NULL;
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}
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if (_rgbSurface) {
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_rgbSurface->free();
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delete _rgbSurface;
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}
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}
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bool JPEGDecoder::loadStream(Common::SeekableReadStream &stream) {
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// Reset member variables and tables from previous reads
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destroy();
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// Save the input stream
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_stream = &stream;
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bool ok = true;
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bool done = false;
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while (!_stream->eos() && ok && !done) {
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// Read the marker
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// WORKAROUND: While each and every JPEG file should end with
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// an EOI (end of image) tag, in reality this may not be the
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// case. For instance, at least one image in the Masterpiece
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// edition of Myst doesn't, yet other programs are able to read
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// the image without complaining.
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//
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// Apparently, the customary workaround is to insert a fake
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// EOI tag.
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uint16 marker = _stream->readByte();
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bool fakeEOI = false;
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if (_stream->eos()) {
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fakeEOI = true;
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marker = 0xFF;
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}
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if (marker != 0xFF) {
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error("JPEG: Invalid marker[0]: 0x%02X", marker);
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ok = false;
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break;
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}
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while (marker == 0xFF && !_stream->eos())
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marker = _stream->readByte();
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if (_stream->eos()) {
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fakeEOI = true;
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marker = 0xD9;
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}
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if (fakeEOI)
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warning("JPEG: Inserted fake EOI");
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// Process the marker data
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switch (marker) {
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case 0xC0: // Start Of Frame
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ok = readSOF0();
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break;
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case 0xC4: // Define Huffman Tables
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ok = readDHT();
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break;
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case 0xD8: // Start Of Image
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break;
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case 0xD9: // End Of Image
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done = true;
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break;
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case 0xDA: // Start Of Scan
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ok = readSOS();
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break;
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case 0xDB: // Define Quantization Tables
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ok = readDQT();
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break;
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case 0xE0: // JFIF/JFXX segment
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ok = readJFIF();
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break;
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case 0xDD: // Define Restart Interval
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ok = readDRI();
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break;
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case 0xFE: // Comment
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_stream->seek(_stream->readUint16BE() - 2, SEEK_CUR);
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break;
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default: { // Unknown marker
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uint16 size = _stream->readUint16BE();
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if ((marker & 0xE0) != 0xE0)
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warning("JPEG: Unknown marker %02X, skipping %d bytes", marker, size - 2);
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_stream->seek(size - 2, SEEK_CUR);
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}
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}
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}
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_stream = 0;
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return ok;
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}
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bool JPEGDecoder::readJFIF() {
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uint16 length = _stream->readUint16BE();
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uint32 tag = _stream->readUint32BE();
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if (tag != MKTAG('J', 'F', 'I', 'F')) {
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warning("JPEGDecoder::readJFIF() tag mismatch");
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return false;
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}
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if (_stream->readByte() != 0) { // NULL
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warning("JPEGDecoder::readJFIF() NULL mismatch");
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return false;
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}
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byte majorVersion = _stream->readByte();
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byte minorVersion = _stream->readByte();
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if (majorVersion != 1 || minorVersion != 1)
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warning("JPEGDecoder::readJFIF() Non-v1.1 JPEGs may not be handled correctly");
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/* byte densityUnits = */_stream->readByte();
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/* uint16 xDensity = */_stream->readUint16BE();
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/* uint16 yDensity = */_stream->readUint16BE();
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byte thumbW = _stream->readByte();
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byte thumbH = _stream->readByte();
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_stream->seek(thumbW * thumbH * 3, SEEK_CUR); // Ignore thumbnail
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if (length != (thumbW * thumbH * 3) + 16) {
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warning("JPEGDecoder::readJFIF() length mismatch");
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return false;
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}
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return true;
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}
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// Marker 0xC0 (Start Of Frame, Baseline DCT)
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bool JPEGDecoder::readSOF0() {
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debug(5, "JPEG: readSOF0");
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uint16 size = _stream->readUint16BE();
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// Read the sample precision
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uint8 precision = _stream->readByte();
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if (precision != 8) {
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warning("JPEG: Just 8 bit precision supported at the moment");
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return false;
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}
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// Image size
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_h = _stream->readUint16BE();
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_w = _stream->readUint16BE();
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// Number of components
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_numComp = _stream->readByte();
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if (size != 8 + 3 * _numComp) {
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warning("JPEG: Invalid number of components");
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return false;
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}
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// Allocate the new components
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delete[] _components;
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_components = new Component[_numComp];
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// Read the components details
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for (int c = 0; c < _numComp; c++) {
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_components[c].id = _stream->readByte();
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_components[c].factorH = _stream->readByte();
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_components[c].factorV = _components[c].factorH & 0xF;
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_components[c].factorH >>= 4;
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_components[c].quantTableSelector = _stream->readByte();
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}
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return true;
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}
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// Marker 0xC4 (Define Huffman Tables)
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bool JPEGDecoder::readDHT() {
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debug(5, "JPEG: readDHT");
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uint16 size = _stream->readUint16BE() - 2;
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uint32 pos = _stream->pos();
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while ((uint32)_stream->pos() < (size + pos)) {
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// Read the table type and id
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uint8 tableId = _stream->readByte();
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uint8 tableType = tableId >> 4; // type 0: DC, 1: AC
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tableId &= 0xF;
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uint8 tableNum = (tableId << 1) + tableType;
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// Free the Huffman table
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delete[] _huff[tableNum].values; _huff[tableNum].values = NULL;
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delete[] _huff[tableNum].sizes; _huff[tableNum].sizes = NULL;
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delete[] _huff[tableNum].codes; _huff[tableNum].codes = NULL;
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// Read the number of values for each length
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uint8 numValues[16];
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_huff[tableNum].count = 0;
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for (int len = 0; len < 16; len++) {
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numValues[len] = _stream->readByte();
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_huff[tableNum].count += numValues[len];
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}
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// Allocate memory for the current table
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_huff[tableNum].values = new uint8[_huff[tableNum].count];
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_huff[tableNum].sizes = new uint8[_huff[tableNum].count];
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_huff[tableNum].codes = new uint16[_huff[tableNum].count];
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// Read the table contents
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int cur = 0;
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for (int len = 0; len < 16; len++) {
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for (int i = 0; i < numValues[len]; i++) {
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_huff[tableNum].values[cur] = _stream->readByte();
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_huff[tableNum].sizes[cur] = len + 1;
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cur++;
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}
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}
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// Fill the table of Huffman codes
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cur = 0;
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uint16 curCode = 0;
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uint8 curCodeSize = _huff[tableNum].sizes[0];
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while (cur < _huff[tableNum].count) {
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// Increase the code size to fit the request
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while (_huff[tableNum].sizes[cur] != curCodeSize) {
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curCode <<= 1;
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curCodeSize++;
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}
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// Assign the current code
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_huff[tableNum].codes[cur] = curCode;
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curCode++;
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cur++;
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}
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}
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return true;
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}
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// Marker 0xDA (Start Of Scan)
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bool JPEGDecoder::readSOS() {
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debug(5, "JPEG: readSOS");
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uint16 size = _stream->readUint16BE();
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// Number of scan components
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_numScanComp = _stream->readByte();
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if (size != 6 + 2 * _numScanComp) {
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warning("JPEG: Invalid number of components");
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return false;
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}
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// Allocate the new scan components
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delete[] _scanComp;
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_scanComp = new Component *[_numScanComp];
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// Reset the maximum sampling factors
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_maxFactorV = 0;
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_maxFactorH = 0;
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// Component-specification parameters
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for (int c = 0; c < _numScanComp; c++) {
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// Read the desired component id
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uint8 id = _stream->readByte();
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// Search the component with the specified id
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bool found = false;
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for (int i = 0; !found && i < _numComp; i++) {
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if (_components[i].id == id) {
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// We found the desired component
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found = true;
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// Assign the found component to the c'th scan component
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_scanComp[c] = &_components[i];
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}
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}
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if (!found) {
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warning("JPEG: Invalid component");
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return false;
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}
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// Read the entropy table selectors
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_scanComp[c]->DCentropyTableSelector = _stream->readByte();
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_scanComp[c]->ACentropyTableSelector = _scanComp[c]->DCentropyTableSelector & 0xF;
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_scanComp[c]->DCentropyTableSelector >>= 4;
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// Calculate the maximum sampling factors
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if (_scanComp[c]->factorV > _maxFactorV)
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_maxFactorV = _scanComp[c]->factorV;
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if (_scanComp[c]->factorH > _maxFactorH)
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_maxFactorH = _scanComp[c]->factorH;
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// Initialize the DC predictor
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_scanComp[c]->DCpredictor = 0;
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}
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// Start of spectral selection
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if (_stream->readByte() != 0) {
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warning("JPEG: Progressive scanning not supported");
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return false;
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}
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// End of spectral selection
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if (_stream->readByte() != 63) {
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warning("JPEG: Progressive scanning not supported");
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return false;
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}
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// Successive approximation parameters
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if (_stream->readByte() != 0) {
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warning("JPEG: Progressive scanning not supported");
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return false;
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}
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// Entropy coded sequence starts, initialize Huffman decoder
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_bitsNumber = 0;
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// Read all the scan MCUs
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uint16 xMCU = _w / (_maxFactorH * 8);
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uint16 yMCU = _h / (_maxFactorV * 8);
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// Check for non- multiple-of-8 dimensions
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if (_w % (_maxFactorH * 8) != 0)
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xMCU++;
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if (_h % (_maxFactorV * 8) != 0)
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yMCU++;
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// Initialize the scan surfaces
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for (uint16 c = 0; c < _numScanComp; c++) {
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_scanComp[c]->surface.create(xMCU * _maxFactorH * 8, yMCU * _maxFactorV * 8, PixelFormat::createFormatCLUT8());
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}
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bool ok = true;
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uint16 interval = _restartInterval;
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for (int y = 0; ok && (y < yMCU); y++) {
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for (int x = 0; ok && (x < xMCU); x++) {
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ok = readMCU(x, y);
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// If we have a restart interval, we'll need to reset a couple
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// variables
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if (_restartInterval != 0) {
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interval--;
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if (interval == 0) {
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interval = _restartInterval;
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_bitsNumber = 0;
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for (byte i = 0; i < _numScanComp; i++)
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_scanComp[i]->DCpredictor = 0;
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}
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}
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}
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}
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// Trim Component surfaces back to image height and width
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// Note: Code using jpeg must use surface.pitch correctly...
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for (uint16 c = 0; c < _numScanComp; c++) {
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_scanComp[c]->surface.w = _w;
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_scanComp[c]->surface.h = _h;
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}
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return ok;
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}
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// Marker 0xDB (Define Quantization Tables)
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bool JPEGDecoder::readDQT() {
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debug(5, "JPEG: readDQT");
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uint16 size = _stream->readUint16BE() - 2;
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uint32 pos = _stream->pos();
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while ((uint32)_stream->pos() < (pos + size)) {
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// Read the table precision and id
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uint8 tableId = _stream->readByte();
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bool highPrecision = (tableId & 0xF0) != 0;
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// Validate the table id
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tableId &= 0xF;
|
||||
if (tableId > JPEG_MAX_QUANT_TABLES) {
|
||||
warning("JPEG: Invalid number of components");
|
||||
return false;
|
||||
}
|
||||
|
||||
// Create the new table if necessary
|
||||
if (!_quant[tableId])
|
||||
_quant[tableId] = new uint16[64];
|
||||
|
||||
// Read the table (stored in Zig-Zag order)
|
||||
for (int i = 0; i < 64; i++)
|
||||
_quant[tableId][i] = highPrecision ? _stream->readUint16BE() : _stream->readByte();
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
// Marker 0xDD (Define Restart Interval)
|
||||
bool JPEGDecoder::readDRI() {
|
||||
debug(5, "JPEG: readDRI");
|
||||
uint16 size = _stream->readUint16BE() - 2;
|
||||
|
||||
if (size != 2) {
|
||||
warning("JPEG: Invalid DRI size %d", size);
|
||||
return false;
|
||||
}
|
||||
|
||||
_restartInterval = _stream->readUint16BE();
|
||||
debug(5, "Restart interval: %d", _restartInterval);
|
||||
return true;
|
||||
}
|
||||
|
||||
bool JPEGDecoder::readMCU(uint16 xMCU, uint16 yMCU) {
|
||||
bool ok = true;
|
||||
for (int c = 0; ok && (c < _numComp); c++) {
|
||||
// Set the current component
|
||||
_currentComp = _scanComp[c];
|
||||
|
||||
// Read the data units of the current component
|
||||
for (int y = 0; ok && (y < _scanComp[c]->factorV); y++)
|
||||
for (int x = 0; ok && (x < _scanComp[c]->factorH); x++)
|
||||
ok = readDataUnit(xMCU * _scanComp[c]->factorH + x, yMCU * _scanComp[c]->factorV + y);
|
||||
}
|
||||
|
||||
return ok;
|
||||
}
|
||||
|
||||
// triple-butterfly-add (and possible rounding)
|
||||
#define xadd3(xa, xb, xc, xd, h) \
|
||||
p = xa + xb; \
|
||||
n = xa - xb; \
|
||||
xa = p + xc + h; \
|
||||
xb = n + xd + h; \
|
||||
xc = p - xc + h; \
|
||||
xd = n - xd + h;
|
||||
|
||||
// butterfly-mul
|
||||
#define xmul(xa, xb, k1, k2, sh) \
|
||||
n = k1 * (xa + xb); \
|
||||
p = xa; \
|
||||
xa = (n + (k2 - k1) * xb) >> sh; \
|
||||
xb = (n - (k2 + k1) * p) >> sh;
|
||||
|
||||
// IDCT based on public domain code from http://halicery.com/jpeg/idct.html
|
||||
void JPEGDecoder::idct1D8x8(int32 src[8], int32 dest[64], int32 ps, int32 half) {
|
||||
int p, n;
|
||||
|
||||
src[0] <<= 9;
|
||||
src[1] <<= 7;
|
||||
src[3] *= 181;
|
||||
src[4] <<= 9;
|
||||
src[5] *= 181;
|
||||
src[7] <<= 7;
|
||||
|
||||
// Even part
|
||||
xmul(src[6], src[2], 277, 669, 0)
|
||||
xadd3(src[0], src[4], src[6], src[2], half)
|
||||
|
||||
// Odd part
|
||||
xadd3(src[1], src[7], src[3], src[5], 0)
|
||||
xmul(src[5], src[3], 251, 50, 6)
|
||||
xmul(src[1], src[7], 213, 142, 6)
|
||||
|
||||
dest[0 * 8] = (src[0] + src[1]) >> ps;
|
||||
dest[1 * 8] = (src[4] + src[5]) >> ps;
|
||||
dest[2 * 8] = (src[2] + src[3]) >> ps;
|
||||
dest[3 * 8] = (src[6] + src[7]) >> ps;
|
||||
dest[4 * 8] = (src[6] - src[7]) >> ps;
|
||||
dest[5 * 8] = (src[2] - src[3]) >> ps;
|
||||
dest[6 * 8] = (src[4] - src[5]) >> ps;
|
||||
dest[7 * 8] = (src[0] - src[1]) >> ps;
|
||||
}
|
||||
|
||||
void JPEGDecoder::idct2D8x8(int32 block[64]) {
|
||||
int32 tmp[64];
|
||||
|
||||
// Apply 1D IDCT to rows
|
||||
for (int i = 0; i < 8; i++)
|
||||
idct1D8x8(&block[i * 8], &tmp[i], 9, 1 << 8);
|
||||
|
||||
// Apply 1D IDCT to columns
|
||||
for (int i = 0; i < 8; i++)
|
||||
idct1D8x8(&tmp[i * 8], &block[i], 12, 1 << 11);
|
||||
}
|
||||
|
||||
bool JPEGDecoder::readDataUnit(uint16 x, uint16 y) {
|
||||
// Prepare an empty data array
|
||||
int16 readData[64];
|
||||
for (int i = 1; i < 64; i++)
|
||||
readData[i] = 0;
|
||||
|
||||
// Read the DC component
|
||||
readData[0] = _currentComp->DCpredictor + readDC();
|
||||
_currentComp->DCpredictor = readData[0];
|
||||
|
||||
// Read the AC components (stored in Zig-Zag)
|
||||
readAC(readData);
|
||||
|
||||
// Calculate the DCT coefficients from the input sequence
|
||||
int32 block[64];
|
||||
for (uint8 i = 0; i < 64; i++) {
|
||||
// Dequantize
|
||||
int32 val = readData[i];
|
||||
int16 quant = _quant[_currentComp->quantTableSelector][i];
|
||||
val *= quant;
|
||||
|
||||
// Store the normalized coefficients, undoing the Zig-Zag
|
||||
block[_zigZagOrder[i]] = val;
|
||||
}
|
||||
|
||||
// Apply the IDCT
|
||||
idct2D8x8(block);
|
||||
|
||||
// Level shift to make the values unsigned
|
||||
for (int i = 0; i < 64; i++) {
|
||||
block[i] = block[i] + 128;
|
||||
|
||||
if (block[i] < 0)
|
||||
block[i] = 0;
|
||||
|
||||
if (block[i] > 255)
|
||||
block[i] = 255;
|
||||
}
|
||||
|
||||
// Paint the component surface
|
||||
uint8 scalingV = _maxFactorV / _currentComp->factorV;
|
||||
uint8 scalingH = _maxFactorH / _currentComp->factorH;
|
||||
|
||||
// Convert coordinates from MCU blocks to pixels
|
||||
x <<= 3;
|
||||
y <<= 3;
|
||||
|
||||
for (uint8 j = 0; j < 8; j++) {
|
||||
for (uint16 sV = 0; sV < scalingV; sV++) {
|
||||
// Get the beginning of the block line
|
||||
byte *ptr = (byte *)_currentComp->surface.getBasePtr(x * scalingH, (y + j) * scalingV + sV);
|
||||
|
||||
for (uint8 i = 0; i < 8; i++) {
|
||||
for (uint16 sH = 0; sH < scalingH; sH++) {
|
||||
*ptr = (byte)(block[j * 8 + i]);
|
||||
ptr++;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
int16 JPEGDecoder::readDC() {
|
||||
// DC is type 0
|
||||
uint8 tableNum = _currentComp->DCentropyTableSelector << 1;
|
||||
|
||||
// Get the number of bits to read
|
||||
uint8 numBits = readHuff(tableNum);
|
||||
|
||||
// Read the requested bits
|
||||
return readSignedBits(numBits);
|
||||
}
|
||||
|
||||
void JPEGDecoder::readAC(int16 *out) {
|
||||
// AC is type 1
|
||||
uint8 tableNum = (_currentComp->ACentropyTableSelector << 1) + 1;
|
||||
|
||||
// Start reading AC element 1
|
||||
uint8 cur = 1;
|
||||
while (cur < 64) {
|
||||
uint8 s = readHuff(tableNum);
|
||||
uint8 r = s >> 4;
|
||||
s &= 0xF;
|
||||
|
||||
if (s == 0) {
|
||||
if (r == 15) {
|
||||
// Skip 16 values
|
||||
cur += 16;
|
||||
} else {
|
||||
// EOB: end of block
|
||||
cur = 64;
|
||||
}
|
||||
} else {
|
||||
// Skip r values
|
||||
cur += r;
|
||||
|
||||
// Read the next value
|
||||
out[cur] = readSignedBits(s);
|
||||
cur++;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
int16 JPEGDecoder::readSignedBits(uint8 numBits) {
|
||||
uint16 ret = 0;
|
||||
if (numBits > 16)
|
||||
error("requested %d bits", numBits); //XXX
|
||||
|
||||
// MSB=0 for negatives, 1 for positives
|
||||
for (int i = 0; i < numBits; i++)
|
||||
ret = (ret << 1) + readBit();
|
||||
|
||||
// Extend sign bits (PAG109)
|
||||
if (!(ret >> (numBits - 1))) {
|
||||
uint16 tmp = ((uint16)-1 << numBits) + 1;
|
||||
ret = ret + tmp;
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
// TODO: optimize?
|
||||
uint8 JPEGDecoder::readHuff(uint8 table) {
|
||||
bool foundCode = false;
|
||||
uint8 val = 0;
|
||||
|
||||
uint8 cur = 0;
|
||||
uint8 codeSize = 1;
|
||||
uint16 code = readBit();
|
||||
while (!foundCode) {
|
||||
// Prepare a code of the current size
|
||||
while (codeSize < _huff[table].sizes[cur]) {
|
||||
code = (code << 1) + readBit();
|
||||
codeSize++;
|
||||
}
|
||||
|
||||
// Compare the codes of the current size
|
||||
while (!foundCode && (codeSize == _huff[table].sizes[cur])) {
|
||||
if (code == _huff[table].codes[cur]) {
|
||||
// Found the code
|
||||
val = _huff[table].values[cur];
|
||||
foundCode = true;
|
||||
} else {
|
||||
// Continue reading
|
||||
cur++;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return val;
|
||||
}
|
||||
|
||||
uint8 JPEGDecoder::readBit() {
|
||||
// Read a whole byte if necessary
|
||||
if (_bitsNumber == 0) {
|
||||
_bitsData = _stream->readByte();
|
||||
_bitsNumber = 8;
|
||||
|
||||
// Detect markers
|
||||
if (_bitsData == 0xFF) {
|
||||
uint8 byte2 = _stream->readByte();
|
||||
|
||||
// A stuffed 0 validates the previous byte
|
||||
if (byte2 != 0) {
|
||||
if (byte2 == 0xDC) {
|
||||
// DNL marker: Define Number of Lines
|
||||
// TODO: terminate scan
|
||||
warning("DNL marker detected: terminate scan");
|
||||
} else if (byte2 >= 0xD0 && byte2 <= 0xD7) {
|
||||
debug(7, "RST%d marker detected", byte2 & 7);
|
||||
_bitsData = _stream->readByte();
|
||||
} else {
|
||||
warning("Error: marker 0x%02X read in entropy data", byte2);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
_bitsNumber--;
|
||||
|
||||
return (_bitsData & (1 << _bitsNumber)) ? 1 : 0;
|
||||
}
|
||||
|
||||
const Surface *JPEGDecoder::getComponent(uint c) const {
|
||||
for (int i = 0; i < _numComp; i++)
|
||||
if (_components[i].id == c) // We found the desired component
|
||||
return &_components[i].surface;
|
||||
|
||||
error("JPEGDecoder::getComponent: No component %d present", c);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
} // End of Graphics namespace
|
||||
Loading…
Add table
Add a link
Reference in a new issue