| /* |
| * rdgif.c |
| * |
| * Copyright (C) 1991-1997, 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.ijg |
| * file. |
| * |
| * This file contains routines to read input images in GIF format. |
| * |
| * 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 */ |
| |
| typedef unsigned char U_CHAR; |
| #define UCH(x) ((int)(x)) |
| |
| |
| #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.) |
| */ |
| |
| |
| /* 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 *symbol_head; /* => table of prefix symbols */ |
| UINT8 *symbol_tail; /* => table of suffix bytes */ |
| UINT8 *symbol_stack; /* => stack for symbol expansions */ |
| UINT8 *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(j_compress_ptr cinfo, |
| cjpeg_source_ptr sinfo); |
| METHODDEF(JDIMENSION) load_interlaced_image(j_compress_ptr cinfo, |
| cjpeg_source_ptr sinfo); |
| METHODDEF(JDIMENSION) get_interlaced_row(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 int 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 = UCH(sinfo->code_buf[offs + 2]); |
| accum <<= 8; |
| accum |= UCH(sinfo->code_buf[offs + 1]); |
| accum <<= 8; |
| accum |= 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 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 *) |
| (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE, |
| LZW_TABLE_SIZE * sizeof(UINT16)); |
| source->symbol_tail = (UINT8 *) |
| (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE, |
| LZW_TABLE_SIZE * sizeof(UINT8)); |
| source->symbol_stack = (UINT8 *) |
| (*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 = *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. |
| */ |
| |
| GLOBAL(cjpeg_source_ptr) |
| jinit_read_gif(j_compress_ptr cinfo) |
| { |
| 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 (cjpeg_source_ptr)source; |
| } |
| |
| #endif /* GIF_SUPPORTED */ |