/* * The Python Imaging Library. * $Id$ * * 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 || strcmp(context->rawmode, "CMYK;I") == 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