keller: use only meaningful blitters

src/demo/keller.c

@@ -3,17 +3,25 @@
 // show it with each blitter, with a legend
 static int
 visualize(struct notcurses* nc, struct ncvisual* ncv){
-  for(ncblitter_e b = NCBLIT_DEFAULT + 1 ; b < NCBLIT_SIXEL ; ++b){
-    struct timespec ts = { .tv_sec = 0, .tv_nsec = GIG / 2, };
+  ncblitter_e bs[] = {
+    NCBLIT_1x1,
+    NCBLIT_2x1,
+    NCBLIT_2x2,
+    NCBLIT_3x2,
+    NCBLIT_BRAILLE,
+  };
+  for(size_t i = 0 ; i < sizeof(bs) / sizeof(*bs) ; ++i){
+    struct timespec ts;
+    timespec_div(&demodelay, 2, &ts);
     struct ncvisual_options vopts = {
       .scaling = NCSCALE_STRETCH,
-      .blitter = b,
+      .blitter = bs[i],
     };
     struct ncplane* n = ncvisual_render(nc, ncv, &vopts);
     if(n == NULL){
       return -1;
     }
-    const char* name = notcurses_str_blitter(b);
+    const char* name = notcurses_str_blitter(bs[i]);
     ncplane_set_bg_rgb(n, 0);
     int scalex, scaley, truey, truex;
     ncvisual_geom(nc, ncv, &vopts, &truey, &truex, &scaley, &scalex);
@@ -23,7 +31,10 @@ visualize(struct notcurses* nc, struct ncvisual* ncv){
     ncplane_printf_aligned(n, ncplane_dim_y(n) / 2 + 1, NCALIGN_CENTER,
                            "%d:%d pixels -> cell", scalex, scaley);
     int ret = demo_render(nc);
-    demo_nanosleep(nc, &ts);
+    if(ret){
+      return ret;
+    }
+    ret = demo_nanosleep(nc, &ts);
     ncplane_destroy(n);
     if(ret){
       return ret;
@@ -36,7 +47,7 @@ int keller_demo(struct notcurses* nc){
   if(!notcurses_canopen_images(nc)){
     return 0;
   }
-  const char* files[] = { "covid19.jpg", "warmech.bmp", NULL, };
+  const char* files[] = { "covid19.jpg", "aidsrobots.jpeg", "warmech.bmp", "fonts.jpg", NULL, };
   for(const char** file = files ; *file ; ++file){
     char* f = find_data(*file);
     if(f == NULL){