treadimage.c - plan9port - [fork] Plan 9 from user space
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treadimage.c (2432B)
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1 #include <u.h>
2 #include <libc.h>
3 #include <draw.h>
4
5 Image*
6 readimage(Display *d, int fd, int dolock)
7 {
8 char hdr[5*12+1];
9 int dy;
10 int new;
11 uint l, n;
12 int m, j, chunk;
13 int miny, maxy;
14 Rectangle r;
15 int ldepth;
16 u32int chan;
17 uchar *tmp;
18 Image *i;
19
20 if(readn(fd, hdr, 11) != 11)
21 return nil;
22 if(memcmp(hdr, "compressed\n", 11) == 0)
23 return creadimage(d, fd, dolock);
24 if(readn(fd, hdr+11, 5*12-11) != 5*12-11)
25 return nil;
26 if(d)
27 chunk = d->bufsize - 32; /* a little room for header */
28 else
29 chunk = 8192;
30
31 /*
32 * distinguish new channel descriptor from old ldepth.
33 * channel descriptors have letters as well as numbers,
34 * while ldepths are a single digit formatted as %-11d.
35 */
36 new = 0;
37 for(m=0; m<10; m++){
38 if(hdr[m] != ' '){
39 new = 1;
40 break;
41 }
42 }
43 if(hdr[11] != ' '){
44 werrstr("readimage: bad format");
45 return nil;
46 }
47 if(new){
48 hdr[11] = '\0';
49 if((chan = strtochan(hdr)) == 0){
50 werrstr("readimage: bad channel string %s", hdr);
51 return nil;
52 }
53 }else{
54 ldepth = ((int)hdr[10])-'0';
55 if(ldepth<0 || ldepth>3){
56 werrstr("readimage: bad ldepth %d", ldepth);
57 return nil;
58 }
59 chan = drawld2chan[ldepth];
60 }
61
62 r.min.x = atoi(hdr+1*12);
63 r.min.y = atoi(hdr+2*12);
64 r.max.x = atoi(hdr+3*12);
65 r.max.y = atoi(hdr+4*12);
66 if(r.min.x>r.max.x || r.min.y>r.max.y){
67 werrstr("readimage: bad rectangle");
68 return nil;
69 }
70
71 miny = r.min.y;
72 maxy = r.max.y;
73
74 l = bytesperline(r, chantodepth(chan));
75 if(d){
76 if(dolock)
77 lockdisplay(d);
78 i = allocimage(d, r, chan, 0, -1);
79 if(dolock)
80 unlockdisplay(d);
81 if(i == nil)
82 return nil;
83 }else{
84 i = mallocz(sizeof(Image), 1);
85 if(i == nil)
86 return nil;
87 }
88
89 tmp = malloc(chunk);
90 if(tmp == nil)
91 goto Err;
92 while(maxy > miny){
93 dy = maxy - miny;
94 if(dy*l > chunk)
95 dy = chunk/l;
96 if(dy <= 0){
97 werrstr("readimage: image too wide for buffer");
98 goto Err;
99 }
100 n = dy*l;
101 m = readn(fd, tmp, n);
102 if(m != n){
103 werrstr("readimage: read count %d not %d: %r", m, n);
104 Err:
105 if(dolock)
106 lockdisplay(d);
107 Err1:
108 freeimage(i);
109 if(dolock)
110 unlockdisplay(d);
111 free(tmp);
112 return nil;
113 }
114 if(!new) /* an old image: must flip all the bits */
115 for(j=0; j<chunk; j++)
116 tmp[j] ^= 0xFF;
117
118 if(d){
119 if(dolock)
120 lockdisplay(d);
121 if(loadimage(i, Rect(r.min.x, miny, r.max.x, miny+dy), tmp, chunk) <= 0)
122 goto Err1;
123 if(dolock)
124 unlockdisplay(d);
125 }
126 miny += dy;
127 }
128 free(tmp);
129 return i;
130 }