1 /* imgtoppm.c - read an Img-whatnot file and produce a portable pixmap
2 **
3 ** Based on a simple conversion program posted to comp.graphics by Ed Falk.
4 **
5 ** Copyright (C) 1989 by Jef Poskanzer.
6 **
7 ** Permission to use, copy, modify, and distribute this software and its
8 ** documentation for any purpose and without fee is hereby granted, provided
9 ** that the above copyright notice appear in all copies and that both that
10 ** copyright notice and this permission notice appear in supporting
11 ** documentation. This software is provided "as is" without express or
12 ** implied warranty.
13 */
14
15 #include <string.h>
16 #include "ppm.h"
17
18
19
20 int
main(int argc,char ** argv)21 main(int argc, char ** argv) {
22
23 FILE* ifp;
24 pixel* pixelrow;
25 pixel colormap[256];
26 register pixel* pP;
27 unsigned int cols;
28 unsigned int rows;
29 int argn, row, i;
30 int col;
31 pixval maxval;
32 unsigned int cmaplen;
33 int len, gotAT, gotCM, gotPD;
34 unsigned char buf[4096];
35 unsigned char* bP;
36
37
38 ppm_init( &argc, argv );
39
40 argn = 1;
41
42 if ( argn < argc )
43 {
44 ifp = pm_openr( argv[argn] );
45 argn++;
46 }
47 else
48 ifp = stdin;
49
50 if ( argn != argc )
51 pm_usage( "[imgfile]" );
52
53 /* Get signature. */
54 fread( buf, 8, 1, ifp );
55 buf[8] = '\0';
56
57 /* Get entries. */
58 gotAT = 0;
59 gotCM = 0;
60 gotPD = 0;
61 while ( fread( buf, 2, 1, ifp ) == 1 )
62 {
63 if ( strncmp( (char*) buf, "AT", 2 ) == 0 )
64 {
65 if ( fread( buf, 8, 1, ifp ) != 1 )
66 pm_error( "bad attributes header" );
67 buf[8] = '\0';
68 len = atoi( (char*) buf );
69 if ( fread( buf, len, 1, ifp ) != 1 )
70 pm_error( "bad attributes buf" );
71 buf[len] = '\0';
72 sscanf( (char*) buf, "%4u%4u%4u", &cols, &rows, &cmaplen );
73 maxval = 255;
74 gotAT = 1;
75 }
76
77 else if ( strncmp( (char*) buf, "CM", 2 ) == 0 )
78 {
79 if ( ! gotAT )
80 pm_error( "missing attributes header" );
81 if ( fread( buf, 8, 1, ifp ) != 1 )
82 pm_error( "bad colormap header" );
83 buf[8] = '\0';
84 len = atoi((char*) buf );
85 if ( fread( buf, len, 1, ifp ) != 1 )
86 pm_error( "bad colormap buf" );
87 if ( cmaplen * 3 != len )
88 {
89 pm_message(
90 "cmaplen (%d) and colormap buf length (%d) do not match",
91 cmaplen, len );
92 if ( cmaplen * 3 < len )
93 len = cmaplen * 3;
94 else if ( cmaplen * 3 > len )
95 cmaplen = len / 3;
96 }
97 for ( i = 0; i < len; i += 3 )
98 PPM_ASSIGN( colormap[i / 3], buf[i], buf[i + 1], buf[i + 2] );
99 gotCM = 1;
100 }
101
102 else if ( strncmp( (char*) buf, "PD", 2 ) == 0 )
103 {
104 if ( fread( buf, 8, 1, ifp ) != 1 )
105 pm_error( "bad pixel data header" );
106 buf[8] = '\0';
107 len = atoi((char*) buf );
108 if ( len != cols * rows )
109 pm_message(
110 "pixel data length (%d) does not match image size (%d)",
111 len, cols * rows );
112
113 ppm_writeppminit( stdout, cols, rows, maxval, 0 );
114 pixelrow = ppm_allocrow( cols );
115
116 for ( row = 0; row < rows; row++ )
117 {
118 if ( fread( buf, 1, cols, ifp ) != cols )
119 pm_error( "EOF / read error" );
120 for ( col = 0, pP = pixelrow, bP = buf;
121 col < cols; col++, pP++, bP++ )
122 {
123 if ( gotCM )
124 *pP = colormap[*bP];
125 else
126 PPM_ASSIGN( *pP, *bP, *bP, *bP );
127 }
128 ppm_writeppmrow( stdout, pixelrow, cols, maxval, 0 );
129 }
130 gotPD = 1;
131
132 }
133 }
134 if ( ! gotPD )
135 pm_error( "missing pixel data header" );
136
137 pm_close( ifp );
138 /* If the program failed, it previously aborted with nonzero completion
139 code, via various function calls.
140 */
141 return 0;
142 }
143