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283 lines
8.2 KiB
C
283 lines
8.2 KiB
C
/*
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* The Python Imaging Library.
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* $Id$
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*
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* decoder for JPEG image data.
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*
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* history:
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* 1996-05-02 fl Created
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* 1996-05-05 fl Handle small JPEG files correctly
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* 1996-05-28 fl Added "draft mode" support
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* 1997-01-25 fl Added colour conversion override
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* 1998-01-31 fl Adapted to libjpeg 6a
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* 1998-07-12 fl Extended YCbCr support
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* 1998-12-29 fl Added new state to handle suspension in multipass modes
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* 2000-10-12 fl Suppress warnings
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* 2000-12-04 fl Suppress errors beyond end of image data
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*
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* Copyright (c) 1998-2000 Secret Labs AB
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* Copyright (c) 1996-2000 Fredrik Lundh
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*
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* See the README file for details on usage and redistribution.
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*/
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#include "Imaging.h"
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#ifdef HAVE_LIBJPEG
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#undef HAVE_PROTOTYPES
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#undef HAVE_STDLIB_H
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#undef HAVE_STDDEF_H
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#undef UINT8
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#undef UINT16
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#undef UINT32
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#undef INT16
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#undef INT32
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#include "Jpeg.h"
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/* -------------------------------------------------------------------- */
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/* Suspending input handler */
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/* -------------------------------------------------------------------- */
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METHODDEF(void)
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stub(j_decompress_ptr cinfo)
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{
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/* empty */
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}
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METHODDEF(boolean)
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fill_input_buffer(j_decompress_ptr cinfo)
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{
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/* Suspension */
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return FALSE;
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}
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METHODDEF(void)
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skip_input_data(j_decompress_ptr cinfo, long num_bytes)
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{
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JPEGSOURCE* source = (JPEGSOURCE*) cinfo->src;
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if (num_bytes > (long) source->pub.bytes_in_buffer) {
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/* We need to skip more data than we have in the buffer.
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This will force the JPEG library to suspend decoding. */
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source->skip = num_bytes - source->pub.bytes_in_buffer;
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source->pub.next_input_byte += source->pub.bytes_in_buffer;
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source->pub.bytes_in_buffer = 0;
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} else {
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/* Skip portion of the buffer */
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source->pub.bytes_in_buffer -= num_bytes;
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source->pub.next_input_byte += num_bytes;
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source->skip = 0;
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}
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}
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GLOBAL(void)
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jpeg_buffer_src(j_decompress_ptr cinfo, JPEGSOURCE* source)
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{
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cinfo->src = (void*) source;
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/* Prepare for suspending reader */
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source->pub.init_source = stub;
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source->pub.fill_input_buffer = fill_input_buffer;
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source->pub.skip_input_data = skip_input_data;
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source->pub.resync_to_restart = jpeg_resync_to_restart;
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source->pub.term_source = stub;
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source->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
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source->skip = 0;
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}
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/* -------------------------------------------------------------------- */
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/* Error handler */
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/* -------------------------------------------------------------------- */
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METHODDEF(void)
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error(j_common_ptr cinfo)
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{
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JPEGERROR* error;
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error = (JPEGERROR*) cinfo->err;
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longjmp(error->setjmp_buffer, 1);
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}
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METHODDEF(void)
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output(j_common_ptr cinfo)
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{
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/* nothing */
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}
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/* -------------------------------------------------------------------- */
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/* Decoder */
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/* -------------------------------------------------------------------- */
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int
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ImagingJpegDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
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{
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JPEGSTATE* context = (JPEGSTATE*) state->context;
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int ok;
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if (setjmp(context->error.setjmp_buffer)) {
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/* JPEG error handler */
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jpeg_destroy_decompress(&context->cinfo);
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state->errcode = IMAGING_CODEC_BROKEN;
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return -1;
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}
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if (!state->state) {
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/* Setup decompression context */
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context->cinfo.err = jpeg_std_error(&context->error.pub);
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context->error.pub.error_exit = error;
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context->error.pub.output_message = output;
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jpeg_create_decompress(&context->cinfo);
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jpeg_buffer_src(&context->cinfo, &context->source);
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/* Ready to decode */
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state->state = 1;
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}
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/* Load the source buffer */
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context->source.pub.next_input_byte = buf;
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context->source.pub.bytes_in_buffer = bytes;
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if (context->source.skip > 0) {
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skip_input_data(&context->cinfo, context->source.skip);
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if (context->source.skip > 0)
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return context->source.pub.next_input_byte - buf;
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}
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switch (state->state) {
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case 1:
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/* Read JPEG header, until we find an image body. */
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do {
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/* Note that we cannot return unless we have decoded
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as much data as possible. */
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ok = jpeg_read_header(&context->cinfo, FALSE);
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} while (ok == JPEG_HEADER_TABLES_ONLY);
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if (ok == JPEG_SUSPENDED)
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break;
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/* Decoder settings */
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/* jpegmode indicates whats in the file; if not set, we'll
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trust the decoder */
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if (strcmp(context->jpegmode, "L") == 0)
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context->cinfo.jpeg_color_space = JCS_GRAYSCALE;
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else if (strcmp(context->jpegmode, "RGB") == 0)
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context->cinfo.jpeg_color_space = JCS_RGB;
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else if (strcmp(context->jpegmode, "CMYK") == 0)
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context->cinfo.jpeg_color_space = JCS_CMYK;
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else if (strcmp(context->jpegmode, "YCbCr") == 0)
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context->cinfo.jpeg_color_space = JCS_YCbCr;
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else if (strcmp(context->jpegmode, "YCbCrK") == 0) {
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context->cinfo.jpeg_color_space = JCS_YCCK;
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}
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/* rawmode indicates what we want from the decoder. if not
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set, conversions are disabled */
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if (strcmp(context->rawmode, "L") == 0)
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context->cinfo.out_color_space = JCS_GRAYSCALE;
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else if (strcmp(context->rawmode, "RGB") == 0)
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context->cinfo.out_color_space = JCS_RGB;
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else if (strcmp(context->rawmode, "CMYK") == 0 ||
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strcmp(context->rawmode, "CMYK;I") == 0)
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context->cinfo.out_color_space = JCS_CMYK;
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else if (strcmp(context->rawmode, "YCbCr") == 0)
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context->cinfo.out_color_space = JCS_YCbCr;
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else if (strcmp(context->rawmode, "YCbCrK") == 0)
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context->cinfo.out_color_space = JCS_YCCK;
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else {
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/* Disable decoder conversions */
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context->cinfo.jpeg_color_space = JCS_UNKNOWN;
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context->cinfo.out_color_space = JCS_UNKNOWN;
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}
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if (context->scale > 1) {
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context->cinfo.scale_num = 1;
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context->cinfo.scale_denom = context->scale;
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}
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if (context->draft) {
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context->cinfo.do_fancy_upsampling = FALSE;
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context->cinfo.dct_method = JDCT_FASTEST;
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}
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state->state++;
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/* fall through */
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case 2:
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/* Set things up for decompression (this processes the entire
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file if necessary to return data line by line) */
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if (!jpeg_start_decompress(&context->cinfo))
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break;
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state->state++;
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/* fall through */
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case 3:
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/* Decompress a single line of data */
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ok = 1;
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while (state->y < state->ysize) {
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ok = jpeg_read_scanlines(&context->cinfo, &state->buffer, 1);
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if (ok != 1)
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break;
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state->shuffle((UINT8*) im->image[state->y + state->yoff] +
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state->xoff * im->pixelsize, state->buffer,
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state->xsize);
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state->y++;
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}
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if (ok != 1)
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break;
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state->state++;
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/* fall through */
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case 4:
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/* Finish decompression */
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if (!jpeg_finish_decompress(&context->cinfo)) {
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/* FIXME: add strictness mode test */
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if (state->y < state->ysize)
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break;
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}
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/* Clean up */
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jpeg_destroy_decompress(&context->cinfo);
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/* if (jerr.pub.num_warnings) return BROKEN; */
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return -1;
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}
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/* Return number of bytes consumed */
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return context->source.pub.next_input_byte - buf;
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}
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/* -------------------------------------------------------------------- */
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/* Cleanup */
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/* -------------------------------------------------------------------- */
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int ImagingJpegDecodeCleanup(ImagingCodecState state){
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/* called to free the decompression engine when the decode terminates
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due to a corrupt or truncated image
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*/
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JPEGSTATE* context = (JPEGSTATE*) state->context;
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/* Clean up */
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jpeg_destroy_decompress(&context->cinfo);
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return -1;
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}
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#endif
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