don't allow moving a plane above/below itself #71

include/notcurses.h

@@ -345,11 +345,32 @@ API void ncplane_yx(const struct ncplane* n, int* RESTRICT y, int* RESTRICT x);
 API int ncplane_move_top(struct ncplane* n);
 API int ncplane_move_bottom(struct ncplane* n);
 
+// Splice ncplane 'n' out of the z-buffer, and reinsert it above 'above'.
+API int ncplane_move_above_unsafe(struct ncplane* RESTRICT n,
+                                  struct ncplane* RESTRICT above);
+
+static inline int
+ncplane_move_above(struct ncplane* n, struct ncplane* above){
+  if(n == above){
+    return -1;
+  }
+  return ncplane_move_above_unsafe(n, above);
+}
+
 // Splice ncplane 'n' out of the z-buffer, and reinsert it below 'below'.
-API int ncplane_move_below(struct ncplane* RESTRICT n, struct ncplane* RESTRICT below);
+API int ncplane_move_below_unsafe(struct ncplane* RESTRICT n,
+                                  struct ncplane* RESTRICT below);
 
-// Splice ncplane 'n' out of the z-buffer, and reinsert it above 'above'.
-API int ncplane_move_above(struct ncplane* RESTRICT n, struct ncplane* RESTRICT above);
+static inline int
+ncplane_move_below(struct ncplane* n, struct ncplane* below){
+  if(n == below){
+    return -1;
+  }
+  return ncplane_move_below_unsafe(n, below);
+}
+
+// Return the plane above this one, or NULL if this is at the top.
+API struct ncplane* ncplane_below(struct ncplane* n);
 
 // Return the plane below this one, or NULL if this is at the bottom.
 API struct ncplane* ncplane_below(struct ncplane* n);

src/lib/notcurses.c

@@ -1174,7 +1174,7 @@ visible_cell(cell* c, int y, int x, ncplane* n, bool* damage){
 // Call with c->gcluster == 3, falpha == 3, balpha == 0, *retp == topplane.
 
 // 'n' ends up above 'above'
-int ncplane_move_above(ncplane* restrict n, ncplane* restrict above){
+int ncplane_move_above_unsafe(ncplane* restrict n, ncplane* restrict above){
   ncplane** an = find_above_ncplane(n);
   if(an == NULL){
     return -1;
@@ -1190,7 +1190,7 @@ int ncplane_move_above(ncplane* restrict n, ncplane* restrict above){
 }
 
 // 'n' ends up below 'below'
-int ncplane_move_below(ncplane* restrict n, ncplane* restrict below){
+int ncplane_move_below_unsafe(ncplane* restrict n, ncplane* restrict below){
   ncplane** an = find_above_ncplane(n);
   if(an == NULL){
     return -1;