254 lines
6.7 KiB
C
254 lines
6.7 KiB
C
/*
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* rdcolmap.c
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*
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* Copyright (C) 1994-1995, Thomas G. Lane.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This file implements djpeg's "-map file" switch. It reads a source image
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* and constructs a colormap to be supplied to the JPEG decompressor.
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*
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* Currently, these file formats are supported for the map file:
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* GIF: the contents of the GIF's global colormap are used.
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* PPM (either text or raw flavor): the entire file is read and
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* each unique pixel value is entered in the map.
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* Note that reading a large PPM file will be horrendously slow.
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* Typically, a PPM-format map file should contain just one pixel
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* of each desired color. Such a file can be extracted from an
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* ordinary image PPM file with ppmtomap(1).
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*
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* Rescaling a PPM that has a maxval unequal to MAXJSAMPLE is not
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* currently implemented.
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*/
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#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
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#ifdef QUANT_2PASS_SUPPORTED /* otherwise can't quantize to supplied map */
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/* Portions of this code are based on the PBMPLUS library, which is:
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**
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** Copyright (C) 1988 by Jef Poskanzer.
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**
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** Permission to use, copy, modify, and distribute this software and its
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** documentation for any purpose and without fee is hereby granted, provided
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** that the above copyright notice appear in all copies and that both that
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** copyright notice and this permission notice appear in supporting
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** documentation. This software is provided "as is" without express or
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** implied warranty.
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*/
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/*
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* Add a (potentially) new color to the color map.
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*/
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LOCAL void
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add_map_entry (j_decompress_ptr cinfo, int R, int G, int B)
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{
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JSAMPROW colormap0 = cinfo->colormap[0];
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JSAMPROW colormap1 = cinfo->colormap[1];
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JSAMPROW colormap2 = cinfo->colormap[2];
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int ncolors = cinfo->actual_number_of_colors;
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int index;
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/* Check for duplicate color. */
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for (index = 0; index < ncolors; index++) {
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if (GETJSAMPLE(colormap0[index]) == R &&
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GETJSAMPLE(colormap1[index]) == G &&
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GETJSAMPLE(colormap2[index]) == B)
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return; /* color is already in map */
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}
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/* Check for map overflow. */
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if (ncolors >= (MAXJSAMPLE+1))
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ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, (MAXJSAMPLE+1));
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/* OK, add color to map. */
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colormap0[ncolors] = (JSAMPLE) R;
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colormap1[ncolors] = (JSAMPLE) G;
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colormap2[ncolors] = (JSAMPLE) B;
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cinfo->actual_number_of_colors++;
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}
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/*
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* Extract color map from a GIF file.
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*/
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LOCAL void
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read_gif_map (j_decompress_ptr cinfo, FILE * infile)
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{
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int header[13];
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int i, colormaplen;
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int R, G, B;
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/* Initial 'G' has already been read by read_color_map */
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/* Read the rest of the GIF header and logical screen descriptor */
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for (i = 1; i < 13; i++) {
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if ((header[i] = getc(infile)) == EOF)
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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}
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/* Verify GIF Header */
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if (header[1] != 'I' || header[2] != 'F')
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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/* There must be a global color map. */
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if ((header[10] & 0x80) == 0)
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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/* OK, fetch it. */
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colormaplen = 2 << (header[10] & 0x07);
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for (i = 0; i < colormaplen; i++) {
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R = getc(infile);
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G = getc(infile);
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B = getc(infile);
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if (R == EOF || G == EOF || B == EOF)
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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add_map_entry(cinfo,
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R << (BITS_IN_JSAMPLE-8),
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G << (BITS_IN_JSAMPLE-8),
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B << (BITS_IN_JSAMPLE-8));
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}
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}
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/* Support routines for reading PPM */
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LOCAL int
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pbm_getc (FILE * infile)
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/* Read next char, skipping over any comments */
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/* A comment/newline sequence is returned as a newline */
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{
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register int ch;
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ch = getc(infile);
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if (ch == '#') {
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do {
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ch = getc(infile);
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} while (ch != '\n' && ch != EOF);
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}
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return ch;
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}
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LOCAL unsigned int
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read_pbm_integer (j_decompress_ptr cinfo, FILE * infile)
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/* Read an unsigned decimal integer from the PPM file */
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/* Swallows one trailing character after the integer */
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/* Note that on a 16-bit-int machine, only values up to 64k can be read. */
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/* This should not be a problem in practice. */
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{
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register int ch;
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register unsigned int val;
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/* Skip any leading whitespace */
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do {
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ch = pbm_getc(infile);
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if (ch == EOF)
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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} while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
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if (ch < '0' || ch > '9')
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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val = ch - '0';
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while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {
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val *= 10;
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val += ch - '0';
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}
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return val;
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}
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/*
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* Extract color map from a PPM file.
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*/
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LOCAL void
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read_ppm_map (j_decompress_ptr cinfo, FILE * infile)
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{
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int c;
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unsigned int w, h, maxval, row, col;
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int R, G, B;
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/* Initial 'P' has already been read by read_color_map */
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c = getc(infile); /* save format discriminator for a sec */
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/* while we fetch the remaining header info */
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w = read_pbm_integer(cinfo, infile);
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h = read_pbm_integer(cinfo, infile);
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maxval = read_pbm_integer(cinfo, infile);
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if (w <= 0 || h <= 0 || maxval <= 0) /* error check */
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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/* For now, we don't support rescaling from an unusual maxval. */
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if (maxval != (unsigned int) MAXJSAMPLE)
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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switch (c) {
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case '3': /* it's a text-format PPM file */
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for (row = 0; row < h; row++) {
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for (col = 0; col < w; col++) {
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R = read_pbm_integer(cinfo, infile);
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G = read_pbm_integer(cinfo, infile);
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B = read_pbm_integer(cinfo, infile);
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add_map_entry(cinfo, R, G, B);
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}
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}
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break;
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case '6': /* it's a raw-format PPM file */
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for (row = 0; row < h; row++) {
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for (col = 0; col < w; col++) {
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R = pbm_getc(infile);
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G = pbm_getc(infile);
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B = pbm_getc(infile);
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if (R == EOF || G == EOF || B == EOF)
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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add_map_entry(cinfo, R, G, B);
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}
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}
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break;
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default:
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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break;
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}
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}
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/*
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* Main entry point from djpeg.c.
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* Input: opened input file (from file name argument on command line).
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* Output: colormap and actual_number_of_colors fields are set in cinfo.
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*/
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GLOBAL void
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read_color_map (j_decompress_ptr cinfo, FILE * infile)
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{
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/* Allocate space for a color map of maximum supported size. */
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cinfo->colormap = (*cinfo->mem->alloc_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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(JDIMENSION) (MAXJSAMPLE+1), (JDIMENSION) 3);
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cinfo->actual_number_of_colors = 0; /* initialize map to empty */
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/* Read first byte to determine file format */
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switch (getc(infile)) {
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case 'G':
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read_gif_map(cinfo, infile);
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break;
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case 'P':
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read_ppm_map(cinfo, infile);
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break;
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default:
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ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
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break;
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}
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}
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#endif /* QUANT_2PASS_SUPPORTED */
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