ncplane_double_box_cells(), used in sliding-demo #67

include/notcurses.h

@@ -432,18 +432,20 @@ cell_egc_idx(const cell* c){
   return c->gcluster - 0x80;
 }
 
-// load up six cells with the EGCs necessary to draw a light, rounded box.
-// returns 0 on success, -1 on error. on error, any cells this function might
-// have loaded before the error are cell_release()d.
+// load up six cells with the EGCs necessary to draw a box. returns 0 on
+// success, -1 on error. on error, any cells this function might
+// have loaded before the error are cell_release()d. There must be at least
+// six EGCs in gcluster.
 static inline int
-ncplane_rounded_box_cells(struct ncplane* n, cell* ul, cell* ur, cell* ll,
-                          cell* lr, cell* hl, cell* vl){
-  if(cell_load(n, ul, "╭") > 0){
-    if(cell_load(n, ur, "╮") > 0){
-      if(cell_load(n, ll, "╰") > 0){
-        if(cell_load(n, lr, "╯") > 0){
-          if(cell_load(n, hl, "─") > 0){
-            if(cell_load(n, vl, "│") > 0){
+ncplane_box_cells(struct ncplane* n, cell* ul, cell* ur, cell* ll,
+                          cell* lr, cell* hl, cell* vl, const char* gclusters){
+  int ulen;
+  if((ulen = cell_load(n, ul, gclusters)) > 0){
+    if((ulen = cell_load(n, ur, gclusters += ulen)) > 0){
+      if((ulen = cell_load(n, ll, gclusters += ulen)) > 0){
+        if((ulen = cell_load(n, lr, gclusters += ulen)) > 0){
+          if((ulen = cell_load(n, hl, gclusters += ulen)) > 0){
+            if((ulen = cell_load(n, vl, gclusters += ulen)) > 0){
               return 0;
             }
             cell_release(n, hl);
@@ -459,6 +461,18 @@ ncplane_rounded_box_cells(struct ncplane* n, cell* ul, cell* ur, cell* ll,
   return -1;
 }
 
+static inline int
+ncplane_rounded_box_cells(struct ncplane* n, cell* ul, cell* ur, cell* ll,
+                          cell* lr, cell* hl, cell* vl){
+  return ncplane_box_cells(n, ul, ur, ll, lr, hl, vl, "╭╮╰╯─│");
+}
+
+static inline int
+ncplane_double_box_cells(struct ncplane* n, cell* ul, cell* ur, cell* ll,
+                          cell* lr, cell* hl, cell* vl){
+  return ncplane_box_cells(n, ul, ur, ll, lr, hl, vl, "╔╗╚╝═║");
+}
+
 // multimedia functionality
 struct AVFrame;
 

src/demo/sliding.c

@@ -16,12 +16,12 @@ fill_chunk(struct ncplane* n, int idx){
   cell ul = CELL_TRIVIAL_INITIALIZER, ur = CELL_TRIVIAL_INITIALIZER;
   cell ll = CELL_TRIVIAL_INITIALIZER, lr = CELL_TRIVIAL_INITIALIZER;
   cell hl = CELL_TRIVIAL_INITIALIZER, vl = CELL_TRIVIAL_INITIALIZER;
-  if(ncplane_rounded_box_cells(n, &ul, &ur, &ll, &lr, &hl, &vl)){
+  if(ncplane_double_box_cells(n, &ul, &ur, &ll, &lr, &hl, &vl)){
     return -1;
   }
-  int r = 255 - (idx * 3);
-  int g = idx * 3;
-  int b = 255 - (idx * 3);
+  int r = (255 - (idx * 3)) % 256;
+  int g = (idx * 3) % 256;
+  int b = (255 - (idx * 3)) % 256;
   cell_set_fg(&ul, r, g, b);
   cell_set_fg(&ur, r, g, b);
   cell_set_fg(&ll, r, g, b);