diff options
Diffstat (limited to 'Imaging/libImaging/JpegDecode.c')
| -rw-r--r-- | Imaging/libImaging/JpegDecode.c | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/Imaging/libImaging/JpegDecode.c b/Imaging/libImaging/JpegDecode.c new file mode 100644 index 0000000..0e61aef --- /dev/null +++ b/Imaging/libImaging/JpegDecode.c @@ -0,0 +1,266 @@ +/* + * 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 + |