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 }