[pixel] derivce location for raster from plane

src/lib/internal.h

@@ -350,9 +350,7 @@ typedef struct ncpile {
 typedef struct sprixel {
   char* glyph;  // glyph; can be quite large
   int id;       // embedded into glusters field of nccell
-  int y, x;     // position relative to the standard plane
-  int cols;
-  int rows;
+  ncplane* n;   // associated ncplane, provides location and size
   int invalidated;
   struct sprixel* next;
 } sprixel;

src/lib/render.c

@@ -922,7 +922,9 @@ static int
 rasterize_sprixels(notcurses* nc, FILE* out){
   for(sprixel* s = nc->sprixelcache ; s ; s = s->next){
     if(s->invalidated){
-      if(goto_location(nc, out, s->y, s->x)){
+      int y, x;
+      ncplane_yx(s->n, &y, &x);
+      if(goto_location(nc, out, y, x)){
         return -1;
       }
       if(ncfputs(s->glyph, out) < 0){