a

libmemdraw/read.c

@@ -0,0 +1,111 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+
+Memimage*
+readmemimage(int fd)
+{
+	char hdr[5*12+1];
+	int dy;
+	ulong chan;
+	uint l, n;
+	int m, j;
+	int new, miny, maxy;
+	Rectangle r;
+	uchar *tmp;
+	int ldepth, chunk;
+	Memimage *i;
+
+	if(readn(fd, hdr, 11) != 11){
+		werrstr("readimage: short header");
+		return nil;
+	}
+	if(memcmp(hdr, "compressed\n", 11) == 0)
+		return creadmemimage(fd);
+	if(readn(fd, hdr+11, 5*12-11) != 5*12-11){
+		werrstr("readimage: short header (2)");
+		return nil;
+	}
+
+	/*
+	 * distinguish new channel descriptor from old ldepth.
+	 * channel descriptors have letters as well as numbers,
+	 * while ldepths are a single digit formatted as %-11d.
+	 */
+	new = 0;
+	for(m=0; m<10; m++){
+		if(hdr[m] != ' '){
+			new = 1;
+			break;
+		}
+	}
+	if(hdr[11] != ' '){
+		werrstr("readimage: bad format");
+		return nil;
+	}
+	if(new){
+		hdr[11] = '\0';
+		if((chan = strtochan(hdr)) == 0){
+			werrstr("readimage: bad channel string %s", hdr);
+			return nil;
+		}
+	}else{
+		ldepth = ((int)hdr[10])-'0';
+		if(ldepth<0 || ldepth>3){
+			werrstr("readimage: bad ldepth %d", ldepth);
+			return nil;
+		}
+		chan = drawld2chan[ldepth];
+	}
+
+	r.min.x = atoi(hdr+1*12);
+	r.min.y = atoi(hdr+2*12);
+	r.max.x = atoi(hdr+3*12);
+	r.max.y = atoi(hdr+4*12);
+	if(r.min.x>r.max.x || r.min.y>r.max.y){
+		werrstr("readimage: bad rectangle");
+		return nil;
+	}
+
+	miny = r.min.y;
+	maxy = r.max.y;
+
+	l = bytesperline(r, chantodepth(chan));
+	i = allocmemimage(r, chan);
+	if(i == nil)
+		return nil;
+	chunk = 32*1024;
+	if(chunk < l)
+		chunk = l;
+	tmp = malloc(chunk);
+	if(tmp == nil)
+		goto Err;
+	while(maxy > miny){
+		dy = maxy - miny;
+		if(dy*l > chunk)
+			dy = chunk/l;
+		if(dy <= 0){
+			werrstr("readmemimage: image too wide for buffer");
+			goto Err;
+		}
+		n = dy*l;
+		m = readn(fd, tmp, n);
+		if(m != n){
+			werrstr("readmemimage: read count %d not %d: %r", m, n);
+   Err:
+ 			freememimage(i);
+			free(tmp);
+			return nil;
+		}
+		if(!new)	/* an old image: must flip all the bits */
+			for(j=0; j<chunk; j++)
+				tmp[j] ^= 0xFF;
+
+		if(loadmemimage(i, Rect(r.min.x, miny, r.max.x, miny+dy), tmp, chunk) <= 0)
+			goto Err;
+		miny += dy;
+	}
+	free(tmp);
+	return i;
+}