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comparison mupdf-source/thirdparty/libjpeg/rdcolmap.c @ 2:b50eed0cc0ef upstream

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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /*
2 * rdcolmap.c
3 *
4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file implements djpeg's "-map file" switch. It reads a source image
9 * and constructs a colormap to be supplied to the JPEG decompressor.
10 *
11 * Currently, these file formats are supported for the map file:
12 * GIF: the contents of the GIF's global colormap are used.
13 * PPM (either text or raw flavor): the entire file is read and
14 * each unique pixel value is entered in the map.
15 * Note that reading a large PPM file will be horrendously slow.
16 * Typically, a PPM-format map file should contain just one pixel
17 * of each desired color. Such a file can be extracted from an
18 * ordinary image PPM file with ppmtomap(1).
19 *
20 * Rescaling a PPM that has a maxval unequal to MAXJSAMPLE is not
21 * currently implemented.
22 */
23
24 #include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
25
26 #ifdef QUANT_2PASS_SUPPORTED /* otherwise can't quantize to supplied map */
27
28 /* Portions of this code are based on the PBMPLUS library, which is:
29 **
30 ** Copyright (C) 1988 by Jef Poskanzer.
31 **
32 ** Permission to use, copy, modify, and distribute this software and its
33 ** documentation for any purpose and without fee is hereby granted, provided
34 ** that the above copyright notice appear in all copies and that both that
35 ** copyright notice and this permission notice appear in supporting
36 ** documentation. This software is provided "as is" without express or
37 ** implied warranty.
38 */
39
40
41 /*
42 * Add a (potentially) new color to the color map.
43 */
44
45 LOCAL(void)
46 add_map_entry (j_decompress_ptr cinfo, int R, int G, int B)
47 {
48 JSAMPROW colormap0 = cinfo->colormap[0];
49 JSAMPROW colormap1 = cinfo->colormap[1];
50 JSAMPROW colormap2 = cinfo->colormap[2];
51 int ncolors = cinfo->actual_number_of_colors;
52 int index;
53
54 /* Check for duplicate color. */
55 for (index = 0; index < ncolors; index++) {
56 if (GETJSAMPLE(colormap0[index]) == R &&
57 GETJSAMPLE(colormap1[index]) == G &&
58 GETJSAMPLE(colormap2[index]) == B)
59 return; /* color is already in map */
60 }
61
62 /* Check for map overflow. */
63 if (ncolors >= (MAXJSAMPLE+1))
64 ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, (MAXJSAMPLE+1));
65
66 /* OK, add color to map. */
67 colormap0[ncolors] = (JSAMPLE) R;
68 colormap1[ncolors] = (JSAMPLE) G;
69 colormap2[ncolors] = (JSAMPLE) B;
70 cinfo->actual_number_of_colors++;
71 }
72
73
74 /*
75 * Extract color map from a GIF file.
76 */
77
78 LOCAL(void)
79 read_gif_map (j_decompress_ptr cinfo, FILE * infile)
80 {
81 int header[13];
82 int i, colormaplen;
83 int R, G, B;
84
85 /* Initial 'G' has already been read by read_color_map */
86 /* Read the rest of the GIF header and logical screen descriptor */
87 for (i = 1; i < 13; i++) {
88 if ((header[i] = getc(infile)) == EOF)
89 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
90 }
91
92 /* Verify GIF Header */
93 if (header[1] != 'I' || header[2] != 'F')
94 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
95
96 /* There must be a global color map. */
97 if ((header[10] & 0x80) == 0)
98 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
99
100 /* OK, fetch it. */
101 colormaplen = 2 << (header[10] & 0x07);
102
103 for (i = 0; i < colormaplen; i++) {
104 R = getc(infile);
105 G = getc(infile);
106 B = getc(infile);
107 if (R == EOF || G == EOF || B == EOF)
108 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
109 add_map_entry(cinfo,
110 R << (BITS_IN_JSAMPLE-8),
111 G << (BITS_IN_JSAMPLE-8),
112 B << (BITS_IN_JSAMPLE-8));
113 }
114 }
115
116
117 /* Support routines for reading PPM */
118
119
120 LOCAL(int)
121 pbm_getc (FILE * infile)
122 /* Read next char, skipping over any comments */
123 /* A comment/newline sequence is returned as a newline */
124 {
125 register int ch;
126
127 ch = getc(infile);
128 if (ch == '#') {
129 do {
130 ch = getc(infile);
131 } while (ch != '\n' && ch != EOF);
132 }
133 return ch;
134 }
135
136
137 LOCAL(unsigned int)
138 read_pbm_integer (j_decompress_ptr cinfo, FILE * infile)
139 /* Read an unsigned decimal integer from the PPM file */
140 /* Swallows one trailing character after the integer */
141 /* Note that on a 16-bit-int machine, only values up to 64k can be read. */
142 /* This should not be a problem in practice. */
143 {
144 register int ch;
145 register unsigned int val;
146
147 /* Skip any leading whitespace */
148 do {
149 ch = pbm_getc(infile);
150 if (ch == EOF)
151 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
152 } while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
153
154 if (ch < '0' || ch > '9')
155 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
156
157 val = ch - '0';
158 while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {
159 val *= 10;
160 val += ch - '0';
161 }
162 return val;
163 }
164
165
166 /*
167 * Extract color map from a PPM file.
168 */
169
170 LOCAL(void)
171 read_ppm_map (j_decompress_ptr cinfo, FILE * infile)
172 {
173 int c;
174 unsigned int w, h, maxval, row, col;
175 int R, G, B;
176
177 /* Initial 'P' has already been read by read_color_map */
178 c = getc(infile); /* save format discriminator for a sec */
179
180 /* while we fetch the remaining header info */
181 w = read_pbm_integer(cinfo, infile);
182 h = read_pbm_integer(cinfo, infile);
183 maxval = read_pbm_integer(cinfo, infile);
184
185 if (w <= 0 || h <= 0 || maxval <= 0) /* error check */
186 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
187
188 /* For now, we don't support rescaling from an unusual maxval. */
189 if (maxval != (unsigned int) MAXJSAMPLE)
190 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
191
192 switch (c) {
193 case '3': /* it's a text-format PPM file */
194 for (row = 0; row < h; row++) {
195 for (col = 0; col < w; col++) {
196 R = read_pbm_integer(cinfo, infile);
197 G = read_pbm_integer(cinfo, infile);
198 B = read_pbm_integer(cinfo, infile);
199 add_map_entry(cinfo, R, G, B);
200 }
201 }
202 break;
203
204 case '6': /* it's a raw-format PPM file */
205 for (row = 0; row < h; row++) {
206 for (col = 0; col < w; col++) {
207 R = getc(infile);
208 G = getc(infile);
209 B = getc(infile);
210 if (R == EOF || G == EOF || B == EOF)
211 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
212 add_map_entry(cinfo, R, G, B);
213 }
214 }
215 break;
216
217 default:
218 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
219 break;
220 }
221 }
222
223
224 /*
225 * Main entry point from djpeg.c.
226 * Input: opened input file (from file name argument on command line).
227 * Output: colormap and actual_number_of_colors fields are set in cinfo.
228 */
229
230 GLOBAL(void)
231 read_color_map (j_decompress_ptr cinfo, FILE * infile)
232 {
233 /* Allocate space for a color map of maximum supported size. */
234 cinfo->colormap = (*cinfo->mem->alloc_sarray)
235 ((j_common_ptr) cinfo, JPOOL_IMAGE,
236 (JDIMENSION) (MAXJSAMPLE+1), (JDIMENSION) 3);
237 cinfo->actual_number_of_colors = 0; /* initialize map to empty */
238
239 /* Read first byte to determine file format */
240 switch (getc(infile)) {
241 case 'G':
242 read_gif_map(cinfo, infile);
243 break;
244 case 'P':
245 read_ppm_map(cinfo, infile);
246 break;
247 default:
248 ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
249 break;
250 }
251 }
252
253 #endif /* QUANT_2PASS_SUPPORTED */