diff options
Diffstat (limited to 'jpeg/rdgif.c')
| -rw-r--r-- | jpeg/rdgif.c | 667 |
1 files changed, 653 insertions, 14 deletions
diff --git a/jpeg/rdgif.c b/jpeg/rdgif.c index b27c1675d..0cbf8d13f 100644 --- a/jpeg/rdgif.c +++ b/jpeg/rdgif.c @@ -1,28 +1,659 @@ /* * rdgif.c * - * Copyright (C) 1991-1997, Thomas G. Lane. + * Copyright (C) 1991-1996, Thomas G. Lane. + * Modified 2019 by Guido Vollbeding. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains routines to read input images in GIF format. * - ***************************************************************************** - * NOTE: to avoid entanglements with Unisys' patent on LZW compression, * - * the ability to read GIF files has been removed from the IJG distribution. * - * Sorry about that. * - ***************************************************************************** - * - * We are required to state that - * "The Graphics Interchange Format(c) is the Copyright property of - * CompuServe Incorporated. GIF(sm) is a Service Mark property of - * CompuServe Incorporated." + * These routines may need modification for non-Unix environments or + * specialized applications. As they stand, they assume input from + * an ordinary stdio stream. They further assume that reading begins + * at the start of the file; start_input may need work if the + * user interface has already read some data (e.g., to determine that + * the file is indeed GIF format). + */ + +/* + * This code is loosely based on giftoppm from the PBMPLUS distribution + * of Feb. 1991. That file contains the following copyright notice: + * +-------------------------------------------------------------------+ + * | Copyright 1990, David Koblas. | + * | Permission to use, copy, modify, and distribute this software | + * | and its documentation for any purpose and without fee is hereby | + * | granted, provided that the above copyright notice appear in all | + * | copies and that both that copyright notice and this permission | + * | notice appear in supporting documentation. This software is | + * | provided "as is" without express or implied warranty. | + * +-------------------------------------------------------------------+ */ #include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */ #ifdef GIF_SUPPORTED + +/* Macros to deal with unsigned chars as efficiently as compiler allows */ + +#ifdef HAVE_UNSIGNED_CHAR +typedef unsigned char U_CHAR; +#define UCH(x) ((int) (x)) +#else /* !HAVE_UNSIGNED_CHAR */ +typedef char U_CHAR; +#ifdef CHAR_IS_UNSIGNED +#define UCH(x) ((int) (x)) +#else +#define UCH(x) ((int) (x) & 0xFF) +#endif +#endif /* HAVE_UNSIGNED_CHAR */ + + +#define ReadOK(file,buffer,len) (JFREAD(file,buffer,len) == ((size_t) (len))) + + +#define MAXCOLORMAPSIZE 256 /* max # of colors in a GIF colormap */ +#define NUMCOLORS 3 /* # of colors */ +#define CM_RED 0 /* color component numbers */ +#define CM_GREEN 1 +#define CM_BLUE 2 + +#define MAX_LZW_BITS 12 /* maximum LZW code size */ +#define LZW_TABLE_SIZE (1<<MAX_LZW_BITS) /* # of possible LZW symbols */ + +/* Macros for extracting header data --- note we assume chars may be signed */ + +#define LM_to_uint(array, offset) ((unsigned int) UCH(array[offset]) + \ + (((unsigned int) UCH(array[offset+1])) << 8)) + +#define BitSet(byte, bit) ((byte) & (bit)) +#define INTERLACE 0x40 /* mask for bit signifying interlaced image */ +#define COLORMAPFLAG 0x80 /* mask for bit signifying colormap presence */ + + +/* + * LZW decompression tables look like this: + * symbol_head[K] = prefix symbol of any LZW symbol K (0..LZW_TABLE_SIZE-1) + * symbol_tail[K] = suffix byte of any LZW symbol K (0..LZW_TABLE_SIZE-1) + * Note that entries 0..end_code of the above tables are not used, + * since those symbols represent raw bytes or special codes. + * + * The stack represents the not-yet-used expansion of the last LZW symbol. + * In the worst case, a symbol could expand to as many bytes as there are + * LZW symbols, so we allocate LZW_TABLE_SIZE bytes for the stack. + * (This is conservative since that number includes the raw-byte symbols.) + * + * The tables are allocated from FAR heap space since they would use up + * rather a lot of the near data space in a PC. + */ + + +/* Private version of data source object */ + +typedef struct { + struct cjpeg_source_struct pub; /* public fields */ + + j_compress_ptr cinfo; /* back link saves passing separate parm */ + + JSAMPARRAY colormap; /* GIF colormap (converted to my format) */ + + /* State for GetCode and LZWReadByte */ + U_CHAR code_buf[256+4]; /* current input data block */ + int last_byte; /* # of bytes in code_buf */ + int last_bit; /* # of bits in code_buf */ + int cur_bit; /* next bit index to read */ + boolean first_time; /* flags first call to GetCode */ + boolean out_of_blocks; /* TRUE if hit terminator data block */ + + int input_code_size; /* codesize given in GIF file */ + int clear_code, end_code; /* values for Clear and End codes */ + + int code_size; /* current actual code size */ + int limit_code; /* 2^code_size */ + int max_code; /* first unused code value */ + + /* Private state for LZWReadByte */ + int oldcode; /* previous LZW symbol */ + int firstcode; /* first byte of oldcode's expansion */ + + /* LZW symbol table and expansion stack */ + UINT16 FAR *symbol_head; /* => table of prefix symbols */ + UINT8 FAR *symbol_tail; /* => table of suffix bytes */ + UINT8 FAR *symbol_stack; /* => stack for symbol expansions */ + UINT8 FAR *sp; /* stack pointer */ + + /* State for interlaced image processing */ + boolean is_interlaced; /* TRUE if have interlaced image */ + jvirt_sarray_ptr interlaced_image; /* full image in interlaced order */ + JDIMENSION cur_row_number; /* need to know actual row number */ + JDIMENSION pass2_offset; /* # of pixel rows in pass 1 */ + JDIMENSION pass3_offset; /* # of pixel rows in passes 1&2 */ + JDIMENSION pass4_offset; /* # of pixel rows in passes 1,2,3 */ +} gif_source_struct; + +typedef gif_source_struct * gif_source_ptr; + + +/* Forward declarations */ +METHODDEF(JDIMENSION) get_pixel_rows + JPP((j_compress_ptr cinfo, cjpeg_source_ptr sinfo)); +METHODDEF(JDIMENSION) load_interlaced_image + JPP((j_compress_ptr cinfo, cjpeg_source_ptr sinfo)); +METHODDEF(JDIMENSION) get_interlaced_row + JPP((j_compress_ptr cinfo, cjpeg_source_ptr sinfo)); + + +LOCAL(int) +ReadByte (gif_source_ptr sinfo) +/* Read next byte from GIF file */ +{ + register FILE *infile = sinfo->pub.input_file; + register int c; + + if ((c = getc(infile)) == EOF) + ERREXIT(sinfo->cinfo, JERR_INPUT_EOF); + return c; +} + + +LOCAL(int) +GetDataBlock (gif_source_ptr sinfo, U_CHAR *buf) +/* Read a GIF data block, which has a leading count byte */ +/* A zero-length block marks the end of a data block sequence */ +{ + int count; + + count = ReadByte(sinfo); + if (count > 0) { + if (! ReadOK(sinfo->pub.input_file, buf, count)) + ERREXIT(sinfo->cinfo, JERR_INPUT_EOF); + } + return count; +} + + +LOCAL(void) +SkipDataBlocks (gif_source_ptr sinfo) +/* Skip a series of data blocks, until a block terminator is found */ +{ + U_CHAR buf[256]; + + while (GetDataBlock(sinfo, buf) > 0) + /* skip */; +} + + +LOCAL(void) +ReInitLZW (gif_source_ptr sinfo) +/* (Re)initialize LZW state; shared code for startup and Clear processing */ +{ + sinfo->code_size = sinfo->input_code_size + 1; + sinfo->limit_code = sinfo->clear_code << 1; /* 2^code_size */ + sinfo->max_code = sinfo->clear_code + 2; /* first unused code value */ + sinfo->sp = sinfo->symbol_stack; /* init stack to empty */ +} + + +LOCAL(void) +InitLZWCode (gif_source_ptr sinfo) +/* Initialize for a series of LZWReadByte (and hence GetCode) calls */ +{ + /* GetCode initialization */ + sinfo->last_byte = 2; /* make safe to "recopy last two bytes" */ + sinfo->code_buf[0] = 0; + sinfo->code_buf[1] = 0; + sinfo->last_bit = 0; /* nothing in the buffer */ + sinfo->cur_bit = 0; /* force buffer load on first call */ + sinfo->first_time = TRUE; + sinfo->out_of_blocks = FALSE; + + /* LZWReadByte initialization: */ + /* compute special code values (note that these do not change later) */ + sinfo->clear_code = 1 << sinfo->input_code_size; + sinfo->end_code = sinfo->clear_code + 1; + ReInitLZW(sinfo); +} + + +LOCAL(int) +GetCode (gif_source_ptr sinfo) +/* Fetch the next code_size bits from the GIF data */ +/* We assume code_size is less than 16 */ +{ + register INT32 accum; + int offs, count; + + while (sinfo->cur_bit + sinfo->code_size > sinfo->last_bit) { + /* Time to reload the buffer */ + /* First time, share code with Clear case */ + if (sinfo->first_time) { + sinfo->first_time = FALSE; + return sinfo->clear_code; + } + if (sinfo->out_of_blocks) { + WARNMS(sinfo->cinfo, JWRN_GIF_NOMOREDATA); + return sinfo->end_code; /* fake something useful */ + } + /* preserve last two bytes of what we have -- assume code_size <= 16 */ + sinfo->code_buf[0] = sinfo->code_buf[sinfo->last_byte-2]; + sinfo->code_buf[1] = sinfo->code_buf[sinfo->last_byte-1]; + /* Load more bytes; set flag if we reach the terminator block */ + if ((count = GetDataBlock(sinfo, &sinfo->code_buf[2])) == 0) { + sinfo->out_of_blocks = TRUE; + WARNMS(sinfo->cinfo, JWRN_GIF_NOMOREDATA); + return sinfo->end_code; /* fake something useful */ + } + /* Reset counters */ + sinfo->cur_bit = (sinfo->cur_bit - sinfo->last_bit) + 16; + sinfo->last_byte = 2 + count; + sinfo->last_bit = sinfo->last_byte * 8; + } + + /* Form up next 24 bits in accum */ + offs = sinfo->cur_bit >> 3; /* byte containing cur_bit */ + accum = (INT32) UCH(sinfo->code_buf[offs+2]); + accum <<= 8; + accum |= (INT32) UCH(sinfo->code_buf[offs+1]); + accum <<= 8; + accum |= (INT32) UCH(sinfo->code_buf[offs]); + + /* Right-align cur_bit in accum, then mask off desired number of bits */ + accum >>= (sinfo->cur_bit & 7); + sinfo->cur_bit += sinfo->code_size; + return ((int) accum) & ((1 << sinfo->code_size) - 1); +} + + +LOCAL(int) +LZWReadByte (gif_source_ptr sinfo) +/* Read an LZW-compressed byte */ +{ + register int code; /* current working code */ + int incode; /* saves actual input code */ + + /* If any codes are stacked from a previously read symbol, return them */ + if (sinfo->sp > sinfo->symbol_stack) + return (int) *(-- sinfo->sp); + + /* Time to read a new symbol */ + code = GetCode(sinfo); + + if (code == sinfo->clear_code) { + /* Reinit state, swallow any extra Clear codes, and */ + /* return next code, which is expected to be a raw byte. */ + ReInitLZW(sinfo); + do { + code = GetCode(sinfo); + } while (code == sinfo->clear_code); + if (code > sinfo->clear_code) { /* make sure it is a raw byte */ + WARNMS(sinfo->cinfo, JWRN_GIF_BADDATA); + code = 0; /* use something valid */ + } + /* make firstcode, oldcode valid! */ + sinfo->firstcode = sinfo->oldcode = code; + return code; + } + + if (code == sinfo->end_code) { + /* Skip the rest of the image, unless GetCode already read terminator */ + if (! sinfo->out_of_blocks) { + SkipDataBlocks(sinfo); + sinfo->out_of_blocks = TRUE; + } + /* Complain that there's not enough data */ + WARNMS(sinfo->cinfo, JWRN_GIF_ENDCODE); + /* Pad data with 0's */ + return 0; /* fake something usable */ + } + + /* Got normal raw byte or LZW symbol */ + incode = code; /* save for a moment */ + + if (code >= sinfo->max_code) { /* special case for not-yet-defined symbol */ + /* code == max_code is OK; anything bigger is bad data */ + if (code > sinfo->max_code) { + WARNMS(sinfo->cinfo, JWRN_GIF_BADDATA); + incode = 0; /* prevent creation of loops in symbol table */ + } + /* this symbol will be defined as oldcode/firstcode */ + *(sinfo->sp++) = (UINT8) sinfo->firstcode; + code = sinfo->oldcode; + } + + /* If it's a symbol, expand it into the stack */ + while (code >= sinfo->clear_code) { + *(sinfo->sp++) = sinfo->symbol_tail[code]; /* tail is a byte value */ + code = sinfo->symbol_head[code]; /* head is another LZW symbol */ + } + /* At this point code just represents a raw byte */ + sinfo->firstcode = code; /* save for possible future use */ + + /* If there's room in table... */ + if ((code = sinfo->max_code) < LZW_TABLE_SIZE) { + /* Define a new symbol = prev sym + head of this sym's expansion */ + sinfo->symbol_head[code] = (UINT16) sinfo->oldcode; + sinfo->symbol_tail[code] = (UINT8) sinfo->firstcode; + sinfo->max_code++; + /* Is it time to increase code_size? */ + if (sinfo->max_code >= sinfo->limit_code && + sinfo->code_size < MAX_LZW_BITS) { + sinfo->code_size++; + sinfo->limit_code <<= 1; /* keep equal to 2^code_size */ + } + } + + sinfo->oldcode = incode; /* save last input symbol for future use */ + return sinfo->firstcode; /* return first byte of symbol's expansion */ +} + + +LOCAL(void) +ReadColorMap (gif_source_ptr sinfo, int cmaplen, JSAMPARRAY cmap) +/* Read a GIF colormap */ +{ + int i; + + for (i = 0; i < cmaplen; i++) { +#if BITS_IN_JSAMPLE == 8 +#define UPSCALE(x) (x) +#else +#define UPSCALE(x) ((x) << (BITS_IN_JSAMPLE-8)) +#endif + cmap[CM_RED ][i] = (JSAMPLE) UPSCALE(ReadByte(sinfo)); + cmap[CM_GREEN][i] = (JSAMPLE) UPSCALE(ReadByte(sinfo)); + cmap[CM_BLUE ][i] = (JSAMPLE) UPSCALE(ReadByte(sinfo)); + } +} + + +LOCAL(void) +DoExtension (gif_source_ptr sinfo) +/* Process an extension block */ +/* Currently we ignore 'em all */ +{ + int extlabel; + + /* Read extension label byte */ + extlabel = ReadByte(sinfo); + TRACEMS1(sinfo->cinfo, 1, JTRC_GIF_EXTENSION, extlabel); + /* Skip the data block(s) associated with the extension */ + SkipDataBlocks(sinfo); +} + + +/* + * Read the file header; return image size and component count. + */ + +METHODDEF(void) +start_input_gif (j_compress_ptr cinfo, cjpeg_source_ptr sinfo) +{ + gif_source_ptr source = (gif_source_ptr) sinfo; + U_CHAR hdrbuf[10]; /* workspace for reading control blocks */ + unsigned int width, height; /* image dimensions */ + int colormaplen, aspectRatio; + int c; + + /* Read and verify GIF Header */ + if (! ReadOK(source->pub.input_file, hdrbuf, 6)) + ERREXIT(cinfo, JERR_GIF_NOT); + if (hdrbuf[0] != 'G' || hdrbuf[1] != 'I' || hdrbuf[2] != 'F') + ERREXIT(cinfo, JERR_GIF_NOT); + /* Check for expected version numbers. + * If unknown version, give warning and try to process anyway; + * this is per recommendation in GIF89a standard. + */ + if ((hdrbuf[3] != '8' || hdrbuf[4] != '7' || hdrbuf[5] != 'a') && + (hdrbuf[3] != '8' || hdrbuf[4] != '9' || hdrbuf[5] != 'a')) + TRACEMS3(cinfo, 1, JTRC_GIF_BADVERSION, hdrbuf[3], hdrbuf[4], hdrbuf[5]); + + /* Read and decipher Logical Screen Descriptor */ + if (! ReadOK(source->pub.input_file, hdrbuf, 7)) + ERREXIT(cinfo, JERR_INPUT_EOF); + width = LM_to_uint(hdrbuf, 0); + height = LM_to_uint(hdrbuf, 2); + /* we ignore the color resolution, sort flag, and background color index */ + aspectRatio = UCH(hdrbuf[6]); + if (aspectRatio != 0 && aspectRatio != 49) + TRACEMS(cinfo, 1, JTRC_GIF_NONSQUARE); + + /* Allocate space to store the colormap */ + source->colormap = (*cinfo->mem->alloc_sarray) ((j_common_ptr) cinfo, + JPOOL_IMAGE, (JDIMENSION) MAXCOLORMAPSIZE, (JDIMENSION) NUMCOLORS); + colormaplen = 0; /* indicate initialization */ + + /* Read global colormap if header indicates it is present */ + if (BitSet(hdrbuf[4], COLORMAPFLAG)) { + colormaplen = 2 << (hdrbuf[4] & 0x07); + ReadColorMap(source, colormaplen, source->colormap); + } + + /* Scan until we reach start of desired image. + * We don't currently support skipping images, but could add it easily. + */ + for (;;) { + c = ReadByte(source); + + if (c == ';') /* GIF terminator?? */ + ERREXIT(cinfo, JERR_GIF_IMAGENOTFOUND); + + if (c == '!') { /* Extension */ + DoExtension(source); + continue; + } + + if (c != ',') { /* Not an image separator? */ + WARNMS1(cinfo, JWRN_GIF_CHAR, c); + continue; + } + + /* Read and decipher Local Image Descriptor */ + if (! ReadOK(source->pub.input_file, hdrbuf, 9)) + ERREXIT(cinfo, JERR_INPUT_EOF); + /* we ignore top/left position info, also sort flag */ + width = LM_to_uint(hdrbuf, 4); + height = LM_to_uint(hdrbuf, 6); + source->is_interlaced = (BitSet(hdrbuf[8], INTERLACE) != 0); + + /* Read local colormap if header indicates it is present */ + /* Note: if we wanted to support skipping images, */ + /* we'd need to skip rather than read colormap for ignored images */ + if (BitSet(hdrbuf[8], COLORMAPFLAG)) { + colormaplen = 2 << (hdrbuf[8] & 0x07); + ReadColorMap(source, colormaplen, source->colormap); + } + + source->input_code_size = ReadByte(source); /* get min-code-size byte */ + if (source->input_code_size < 2 || source->input_code_size > 8) + ERREXIT1(cinfo, JERR_GIF_CODESIZE, source->input_code_size); + + /* Reached desired image, so break out of loop */ + /* If we wanted to skip this image, */ + /* we'd call SkipDataBlocks and then continue the loop */ + break; + } + + /* Prepare to read selected image: first initialize LZW decompressor */ + source->symbol_head = (UINT16 FAR *) (*cinfo->mem->alloc_large) + ((j_common_ptr) cinfo, JPOOL_IMAGE, LZW_TABLE_SIZE * SIZEOF(UINT16)); + source->symbol_tail = (UINT8 FAR *) (*cinfo->mem->alloc_large) + ((j_common_ptr) cinfo, JPOOL_IMAGE, LZW_TABLE_SIZE * SIZEOF(UINT8)); + source->symbol_stack = (UINT8 FAR *) (*cinfo->mem->alloc_large) + ((j_common_ptr) cinfo, JPOOL_IMAGE, LZW_TABLE_SIZE * SIZEOF(UINT8)); + InitLZWCode(source); + + /* + * If image is interlaced, we read it into a full-size sample array, + * decompressing as we go; then get_interlaced_row selects rows from the + * sample array in the proper order. + */ + if (source->is_interlaced) { + /* We request the virtual array now, but can't access it until virtual + * arrays have been allocated. Hence, the actual work of reading the + * image is postponed until the first call to get_pixel_rows. + */ + source->interlaced_image = (*cinfo->mem->request_virt_sarray) + ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE, + (JDIMENSION) width, (JDIMENSION) height, (JDIMENSION) 1); + if (cinfo->progress != NULL) { + cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress; + progress->total_extra_passes++; /* count file input as separate pass */ + } + source->pub.get_pixel_rows = load_interlaced_image; + } else { + source->pub.get_pixel_rows = get_pixel_rows; + } + + /* Create compressor input buffer. */ + source->pub.buffer = (*cinfo->mem->alloc_sarray) ((j_common_ptr) cinfo, + JPOOL_IMAGE, (JDIMENSION) width * NUMCOLORS, (JDIMENSION) 1); + source->pub.buffer_height = 1; + + /* Pad colormap for safety. */ + for (c = colormaplen; c < source->clear_code; c++) { + source->colormap[CM_RED ][c] = + source->colormap[CM_GREEN][c] = + source->colormap[CM_BLUE ][c] = CENTERJSAMPLE; + } + + /* Return info about the image. */ + cinfo->in_color_space = JCS_RGB; + cinfo->input_components = NUMCOLORS; + cinfo->data_precision = BITS_IN_JSAMPLE; /* we always rescale data to this */ + cinfo->image_width = width; + cinfo->image_height = height; + + TRACEMS3(cinfo, 1, JTRC_GIF, width, height, colormaplen); +} + + +/* + * Read one row of pixels. + * This version is used for noninterlaced GIF images: + * we read directly from the GIF file. + */ + +METHODDEF(JDIMENSION) +get_pixel_rows (j_compress_ptr cinfo, cjpeg_source_ptr sinfo) +{ + gif_source_ptr source = (gif_source_ptr) sinfo; + register int c; + register JSAMPROW ptr; + register JDIMENSION col; + register JSAMPARRAY colormap = source->colormap; + + ptr = source->pub.buffer[0]; + for (col = cinfo->image_width; col > 0; col--) { + c = LZWReadByte(source); + *ptr++ = colormap[CM_RED ][c]; + *ptr++ = colormap[CM_GREEN][c]; + *ptr++ = colormap[CM_BLUE ][c]; + } + return 1; +} + + +/* + * Read one row of pixels. + * This version is used for the first call on get_pixel_rows when + * reading an interlaced GIF file: we read the whole image into memory. + */ + +METHODDEF(JDIMENSION) +load_interlaced_image (j_compress_ptr cinfo, cjpeg_source_ptr sinfo) +{ + gif_source_ptr source = (gif_source_ptr) sinfo; + register JSAMPROW sptr; + register JDIMENSION col; + JDIMENSION row; + cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress; + + /* Read the interlaced image into the virtual array we've created. */ + for (row = 0; row < cinfo->image_height; row++) { + if (progress != NULL) { + progress->pub.pass_counter = (long) row; + progress->pub.pass_limit = (long) cinfo->image_height; + (*progress->pub.progress_monitor) ((j_common_ptr) cinfo); + } + sptr = * (*cinfo->mem->access_virt_sarray) ((j_common_ptr) cinfo, + source->interlaced_image, row, (JDIMENSION) 1, TRUE); + for (col = cinfo->image_width; col > 0; col--) { + *sptr++ = (JSAMPLE) LZWReadByte(source); + } + } + if (progress != NULL) + progress->completed_extra_passes++; + + /* Replace method pointer so subsequent calls don't come here. */ + source->pub.get_pixel_rows = get_interlaced_row; + /* Initialize for get_interlaced_row, and perform first call on it. */ + source->cur_row_number = 0; + source->pass2_offset = (cinfo->image_height + 7) / 8; + source->pass3_offset = source->pass2_offset + (cinfo->image_height + 3) / 8; + source->pass4_offset = source->pass3_offset + (cinfo->image_height + 1) / 4; + + return get_interlaced_row(cinfo, sinfo); +} + + +/* + * Read one row of pixels. + * This version is used for interlaced GIF images: + * we read from the virtual array. + */ + +METHODDEF(JDIMENSION) +get_interlaced_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo) +{ + gif_source_ptr source = (gif_source_ptr) sinfo; + register int c; + register JSAMPROW sptr, ptr; + register JDIMENSION col; + register JSAMPARRAY colormap = source->colormap; + JDIMENSION irow; + + /* Figure out which row of interlaced image is needed, and access it. */ + switch ((int) (source->cur_row_number & 7)) { + case 0: /* first-pass row */ + irow = source->cur_row_number >> 3; + break; + case 4: /* second-pass row */ + irow = (source->cur_row_number >> 3) + source->pass2_offset; + break; + case 2: /* third-pass row */ + case 6: + irow = (source->cur_row_number >> 2) + source->pass3_offset; + break; + default: /* fourth-pass row */ + irow = (source->cur_row_number >> 1) + source->pass4_offset; + } + sptr = * (*cinfo->mem->access_virt_sarray) ((j_common_ptr) cinfo, + source->interlaced_image, irow, (JDIMENSION) 1, FALSE); + /* Scan the row, expand colormap, and output */ + ptr = source->pub.buffer[0]; + for (col = cinfo->image_width; col > 0; col--) { + c = GETJSAMPLE(*sptr++); + *ptr++ = colormap[CM_RED ][c]; + *ptr++ = colormap[CM_GREEN][c]; + *ptr++ = colormap[CM_BLUE ][c]; + } + source->cur_row_number++; /* for next time */ + return 1; +} + + +/* + * Finish up at the end of the file. + */ + +METHODDEF(void) +finish_input_gif (j_compress_ptr cinfo, cjpeg_source_ptr sinfo) +{ + /* no work */ +} + + /* * The module selection routine for GIF format input. */ @@ -30,9 +661,17 @@ GLOBAL(cjpeg_source_ptr) jinit_read_gif (j_compress_ptr cinfo) { - fprintf(stderr, "GIF input is unsupported for legal reasons. Sorry.\n"); - exit(EXIT_FAILURE); - return NULL; /* keep compiler happy */ + gif_source_ptr source; + + /* Create module interface object */ + source = (gif_source_ptr) (*cinfo->mem->alloc_small) + ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(gif_source_struct)); + source->cinfo = cinfo; /* make back link for subroutines */ + /* Fill in method ptrs, except get_pixel_rows which start_input sets */ + source->pub.start_input = start_input_gif; + source->pub.finish_input = finish_input_gif; + + return &source->pub; } #endif /* GIF_SUPPORTED */ |