ref: fe5d1976a0b4376c955ca8423eb9005f5d035403
dir: /sys/src/libdraw/readimage.c/
#include <u.h> #include <libc.h> #include <draw.h> Image* readimage(Display *d, int fd, int dolock) { char hdr[5*12+1]; int dy; int new; uint l, n; int m, j, chunk; int miny, maxy; Rectangle r; int ldepth; ulong chan; uchar *tmp; Image *i; if(readn(fd, hdr, 11) != 11) return nil; if(memcmp(hdr, "compressed\n", 11) == 0){ if(i = creadimage(d, fd, dolock)) goto Done; return nil; } if(readn(fd, hdr+11, 5*12-11) != 5*12-11) return nil; if(d != nil) chunk = d->bufsize - 32; /* a little room for header */ else { chunk = iounit(fd); if(chunk <= 0) chunk = IOUNIT; } /* * 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)); if(l > chunk) chunk = l; if(d != nil){ if(dolock) lockdisplay(d); i = allocimage(d, r, chan, 0, -1); if(dolock) unlockdisplay(d); if(i == nil) return nil; }else{ i = mallocz(sizeof(Image), 1); if(i == nil) return nil; } tmp = malloc(chunk); if(tmp == nil) goto Err; while(maxy > miny){ dy = maxy - miny; if(dy*l > chunk) dy = chunk/l; n = dy*l; m = readn(fd, tmp, n); if(m != n){ werrstr("readimage: read count %d not %d: %r", m, n); Err: if(dolock) lockdisplay(d); Err1: freeimage(i); if(dolock) unlockdisplay(d); free(tmp); return nil; } if(!new) /* an old image: must flip all the bits */ for(j=0; j<chunk; j++) tmp[j] ^= 0xFF; if(d != nil){ if(dolock) lockdisplay(d); if(loadimage(i, Rect(r.min.x, miny, r.max.x, miny+dy), tmp, chunk) <= 0) goto Err1; if(dolock) unlockdisplay(d); } miny += dy; } free(tmp); Done: setmalloctag(i, getcallerpc(&d)); return i; }