GdkPixbufLoader and tiff files

[Diego Zuccato <diego otello alma unibo it>]

Hello all.

I'm trying to use GdkPixbufLoader to detect some info on tiff files.

What I'm doing is (omitting error checks):
GdkPixbufLoader *pbl=gdk_pixbuf_loader_new();
// tested new_with_type("tiff", NULL) too !
FILE *f=fopen(file, "rb");
if(f) {
  char buff[512];
  gint siz;
  do {
    siz=fread(buff, 512, 1, f);
    gdk_pixbuf_loader_write(pbl, buff, siz, NULL);
    pb=gdk_pixbuf_loader_get_pixbuf(pbl);
  } while(siz && !pb);
  if(pb) {
    x=gdk_pixbuf_get_width(pb);
    y=gdk_pixbuf_get_height(pb);
    c=gdk_pixbuf_get_bits_per_sample(pb)*gdk_pixbuf_get_n_channels(pb);
  }
  gdk_pixbuf_loader_close(pbl, NULL);
  fclose(f);
}

It works ok for jpg files, but fails ("unrecognized image file format")
on tiff files.
THE SAME tiff file is loaded correctly by gdk_pixbuf_new_from file, so I
think the needed libs are OK.

Am I missing something (as usual)? 

Tks,
 Diego.