ncdirect_render_image(): handle newlines properly

in ncdirect_render_image(), we want to emit newlines if and
only if we did not hit the right border. we want to emit
cuds (cursor downs) if and only if we've hit the bottom
border. this resolves all mysteries of blank lines, eliminating
a FIXME. it also fixes ncneofetch's image display on very
wide terminals. closes #756. also removes the display semaphore
in ncneofetch, using a more natural pthread_join().

src/fetch/main.c

@@ -397,7 +397,6 @@ infoplane(struct ncdirect* ncd, const fetched_info* fi){
 struct marshal {
   struct ncdirect* nc;
   const distro_info* dinfo;
-  sem_t sem;
 };
 
 static void*
@@ -408,13 +407,10 @@ display_thread(void* vmarshal){
     if(m->dinfo->logofile){
       if(ncdirect_render_image(m->nc, m->dinfo->logofile, NCBLIT_2x2,
                                NCSCALE_SCALE) != NCERR_SUCCESS){
-        sem_post(&m->sem);
         return NULL;
       }
     }
   }
-  sem_post(&m->sem);
-  pthread_detach(pthread_self());
   return NULL;
 }
 
@@ -438,17 +434,16 @@ ncneofetch(struct ncdirect* nc){
     .nc = nc,
     .dinfo = fi.distro,
   };
-  sem_init(&display_marshal.sem, 0, 0);
   pthread_t tid;
-  if(pthread_create(&tid, NULL, display_thread, &display_marshal)){
-    sem_post(&display_marshal.sem);
-  }
+  const bool launched = !pthread_create(&tid, NULL, display_thread, &display_marshal);
   unix_gethostname(&fi);
   unix_getusername(&fi);
   fetch_env_vars(&fi);
   fetch_x_props(&fi);
   fetch_cpu_info(&fi);
-  sem_wait(&display_marshal.sem);
+  if(launched){
+    pthread_join(tid, NULL);
+  }
   if(infoplane(nc, &fi)){
     return -1;
   }

src/lib/direct.cpp

@@ -254,6 +254,8 @@ int ncdirect_cursor_pop(ncdirect* n){
 
 static int
 ncdirect_dump_plane(ncdirect* n, const ncplane* np){
+  const int totx = ncdirect_dim_x(n);
+  const int toty = ncdirect_dim_y(n);
   int dimy, dimx;
   ncplane_dim_yx(np, &dimy, &dimx);
   for(int y = 0 ; y < dimy ; ++y){
@@ -266,16 +268,24 @@ ncdirect_dump_plane(ncdirect* n, const ncplane* np){
       }
       ncdirect_fg(n, channels_fg(channels));
       ncdirect_bg(n, channels_bg(channels));
-//fprintf(stdout, "%03d/%03d [%s] (%03dx%03d)\n", y, x, egc, dimy, dimx);
+//fprintf(stderr, "%03d/%03d [%s] (%03dx%03d)\n", y, x, egc, dimy, dimx);
       if(printf("%s", strlen(egc) == 0 ? " " : egc) < 0){
         return -1;
       }
     }
     // FIXME mystifyingly, we require this cursor_left() when using 2x2, but must
     // not have it when using 2x1 (we insert blank lines otherwise). don't paper
     // over it with a conditional, but instead get to the bottom of this FIXME.
+    if(dimx < totx){
+      ncdirect_bg_default(n);
+      if(putchar('\n') == EOF){
+        return -1;
+      }
+    }
     ncdirect_cursor_left(n, dimx);
-    //ncdirect_cursor_down(n, 1);
+    if(y == toty){
+      ncdirect_cursor_down(n, 1);
+    }
   }
   return 0;
 }
@@ -332,7 +342,9 @@ nc_err_e ncdirect_render_image(ncdirect* n, const char* file, ncblitter_e blitte
     return NCERR_SYSTEM;
   }
   ncvisual_destroy(ncv);
-  ncdirect_dump_plane(n, faken);
+  if(ncdirect_dump_plane(n, faken)){
+    return NCERR_SYSTEM;
+  }
   free_plane(faken);
   return NCERR_SUCCESS;
 }