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/*
* The Python Imaging Library.
* $Id: JpegDecode.c 2134 2004-10-06 08:55:20Z fredrik $
*
* decoder for JPEG image data.
*
* history:
* 1996-05-02 fl Created
* 1996-05-05 fl Handle small JPEG files correctly
* 1996-05-28 fl Added "draft mode" support
* 1997-01-25 fl Added colour conversion override
* 1998-01-31 fl Adapted to libjpeg 6a
* 1998-07-12 fl Extended YCbCr support
* 1998-12-29 fl Added new state to handle suspension in multipass modes
* 2000-10-12 fl Suppress warnings
* 2000-12-04 fl Suppress errors beyond end of image data
*
* Copyright (c) 1998-2000 Secret Labs AB
* Copyright (c) 1996-2000 Fredrik Lundh
*
* See the README file for details on usage and redistribution.
*/
#include "Imaging.h"
#ifdef HAVE_LIBJPEG
#undef HAVE_PROTOTYPES
#undef HAVE_STDLIB_H
#undef HAVE_STDDEF_H
#undef UINT8
#undef UINT16
#undef UINT32
#undef INT16
#undef INT32
#include "Jpeg.h"
/* -------------------------------------------------------------------- */
/* Suspending input handler */
/* -------------------------------------------------------------------- */
METHODDEF(void)
stub(j_decompress_ptr cinfo)
{
/* empty */
}
METHODDEF(boolean)
fill_input_buffer(j_decompress_ptr cinfo)
{
/* Suspension */
return FALSE;
}
METHODDEF(void)
skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
JPEGSOURCE* source = (JPEGSOURCE*) cinfo->src;
if (num_bytes > (long) source->pub.bytes_in_buffer) {
/* We need to skip more data than we have in the buffer.
This will force the JPEG library to suspend decoding. */
source->skip = num_bytes - source->pub.bytes_in_buffer;
source->pub.next_input_byte += source->pub.bytes_in_buffer;
source->pub.bytes_in_buffer = 0;
} else {
/* Skip portion of the buffer */
source->pub.bytes_in_buffer -= num_bytes;
source->pub.next_input_byte += num_bytes;
source->skip = 0;
}
}
GLOBAL(void)
jpeg_buffer_src(j_decompress_ptr cinfo, JPEGSOURCE* source)
{
cinfo->src = (void*) source;
/* Prepare for suspending reader */
source->pub.init_source = stub;
source->pub.fill_input_buffer = fill_input_buffer;
source->pub.skip_input_data = skip_input_data;
source->pub.resync_to_restart = jpeg_resync_to_restart;
source->pub.term_source = stub;
source->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
source->skip = 0;
}
/* -------------------------------------------------------------------- */
/* Error handler */
/* -------------------------------------------------------------------- */
METHODDEF(void)
error(j_common_ptr cinfo)
{
JPEGERROR* error;
error = (JPEGERROR*) cinfo->err;
longjmp(error->setjmp_buffer, 1);
}
METHODDEF(void)
output(j_common_ptr cinfo)
{
/* nothing */
}
/* -------------------------------------------------------------------- */
/* Decoder */
/* -------------------------------------------------------------------- */
int
ImagingJpegDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
{
JPEGSTATE* context = (JPEGSTATE*) state->context;
int ok;
if (setjmp(context->error.setjmp_buffer)) {
/* JPEG error handler */
jpeg_destroy_decompress(&context->cinfo);
state->errcode = IMAGING_CODEC_BROKEN;
return -1;
}
if (!state->state) {
/* Setup decompression context */
context->cinfo.err = jpeg_std_error(&context->error.pub);
context->error.pub.error_exit = error;
context->error.pub.output_message = output;
jpeg_create_decompress(&context->cinfo);
jpeg_buffer_src(&context->cinfo, &context->source);
/* Ready to decode */
state->state = 1;
}
/* Load the source buffer */
context->source.pub.next_input_byte = buf;
context->source.pub.bytes_in_buffer = bytes;
if (context->source.skip > 0) {
skip_input_data(&context->cinfo, context->source.skip);
if (context->source.skip > 0)
return context->source.pub.next_input_byte - buf;
}
switch (state->state) {
case 1:
/* Read JPEG header, until we find an image body. */
do {
/* Note that we cannot return unless we have decoded
as much data as possible. */
ok = jpeg_read_header(&context->cinfo, FALSE);
} while (ok == JPEG_HEADER_TABLES_ONLY);
if (ok == JPEG_SUSPENDED)
break;
/* Decoder settings */
/* jpegmode indicates whats in the file; if not set, we'll
trust the decoder */
if (strcmp(context->jpegmode, "L") == 0)
context->cinfo.jpeg_color_space = JCS_GRAYSCALE;
else if (strcmp(context->jpegmode, "RGB") == 0)
context->cinfo.jpeg_color_space = JCS_RGB;
else if (strcmp(context->jpegmode, "CMYK") == 0)
context->cinfo.jpeg_color_space = JCS_CMYK;
else if (strcmp(context->jpegmode, "YCbCr") == 0)
context->cinfo.jpeg_color_space = JCS_YCbCr;
else if (strcmp(context->jpegmode, "YCbCrK") == 0) {
context->cinfo.jpeg_color_space = JCS_YCCK;
}
/* rawmode indicates what we want from the decoder. if not
set, conversions are disabled */
if (strcmp(context->rawmode, "L") == 0)
context->cinfo.out_color_space = JCS_GRAYSCALE;
else if (strcmp(context->rawmode, "RGB") == 0)
context->cinfo.out_color_space = JCS_RGB;
else if (strcmp(context->rawmode, "CMYK") == 0)
context->cinfo.out_color_space = JCS_CMYK;
else if (strcmp(context->rawmode, "YCbCr") == 0)
context->cinfo.out_color_space = JCS_YCbCr;
else if (strcmp(context->rawmode, "YCbCrK") == 0)
context->cinfo.out_color_space = JCS_YCCK;
else {
/* Disable decoder conversions */
context->cinfo.jpeg_color_space = JCS_UNKNOWN;
context->cinfo.out_color_space = JCS_UNKNOWN;
}
if (context->scale > 1) {
context->cinfo.scale_num = 1;
context->cinfo.scale_denom = context->scale;
}
if (context->draft) {
context->cinfo.do_fancy_upsampling = FALSE;
context->cinfo.dct_method = JDCT_FASTEST;
}
state->state++;
/* fall through */
case 2:
/* Set things up for decompression (this processes the entire
file if necessary to return data line by line) */
if (!jpeg_start_decompress(&context->cinfo))
break;
state->state++;
/* fall through */
case 3:
/* Decompress a single line of data */
ok = 1;
while (state->y < state->ysize) {
ok = jpeg_read_scanlines(&context->cinfo, &state->buffer, 1);
if (ok != 1)
break;
state->shuffle((UINT8*) im->image[state->y + state->yoff] +
state->xoff * im->pixelsize, state->buffer,
state->xsize);
state->y++;
}
if (ok != 1)
break;
state->state++;
/* fall through */
case 4:
/* Finish decompression */
if (!jpeg_finish_decompress(&context->cinfo)) {
/* FIXME: add strictness mode test */
if (state->y < state->ysize)
break;
}
/* Clean up */
jpeg_destroy_decompress(&context->cinfo);
/* if (jerr.pub.num_warnings) return BROKEN; */
return -1;
}
/* Return number of bytes consumed */
return context->source.pub.next_input_byte - buf;
}
#endif
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