add simple_box() and heavy_box() forms

NEWS.md

@@ -21,6 +21,9 @@ rearrangements of Notcurses.
   * A new binary is installed, `notcurses-info`. It prints information about
     the terminal environment in which it runs. More information is available
     from its man page, `notcurses-info(1)`.
+  * Added `ncdirect_simple_box()`, `ncdirect_heavy_box()`,
+    `nccells_simple_box()`, and `nccells_heavy_box()`. Publicized
+    `nccells_ascii_box()`. All are `static inline`.
 
 * 2.3.2 (2021-06-03)
   * Fixed a bug affecting certain scalings of `ncvisual` objects created from

include/notcurses/direct.h

@@ -271,6 +271,20 @@ API int ncdirect_box(struct ncdirect* n, uint64_t ul, uint64_t ur,
                      int ylen, int xlen, unsigned ctlword)
   __attribute__ ((nonnull (1)));
 
+__attribute__ ((nonnull (1))) static inline int
+ncdirect_simple_box(struct ncdirect* n, uint64_t ul, uint64_t ur,
+                    uint64_t ll, uint64_t lr,
+                    int ylen, int xlen, unsigned ctlword){
+  return ncdirect_box(n, ul, ur, ll, lr, L"┌┐└┘─│", ylen, xlen, ctlword);
+}
+
+__attribute__ ((nonnull (1))) static inline int
+ncdirect_heavy_box(struct ncdirect* n, uint64_t ul, uint64_t ur,
+                   uint64_t ll, uint64_t lr,
+                   int ylen, int xlen, unsigned ctlword){
+  return ncdirect_box(n, ul, ur, ll, lr, L"┏┓┗┛━┃", ylen, xlen, ctlword);
+}
+
 // ncdirect_box() with the rounded box-drawing characters
 API int ncdirect_rounded_box(struct ncdirect* n, uint64_t ul, uint64_t ur,
                              uint64_t ll, uint64_t lr,

include/notcurses/notcurses.h

@@ -2313,6 +2313,30 @@ API int nccells_rounded_box(struct ncplane* n, uint32_t styles, uint64_t channel
                             nccell* ul, nccell* ur, nccell* ll,
                             nccell* lr, nccell* hl, nccell* vl);
 
+static inline int
+nccells_ascii_box(struct ncplane* n, uint32_t attr, uint64_t channels,
+                  nccell* ul, nccell* ur, nccell* ll, nccell* lr, nccell* hl, nccell* vl){
+  return nccells_load_box(n, attr, channels, ul, ur, ll, lr, hl, vl, "/\\\\/-|");
+}
+
+static inline int
+nccells_simple_box(struct ncplane* n, uint32_t attr, uint64_t channels,
+                   nccell* ul, nccell* ur, nccell* ll, nccell* lr, nccell* hl, nccell* vl){
+  if(notcurses_canutf8(ncplane_notcurses(n))){
+    return nccells_load_box(n, attr, channels, ul, ur, ll, lr, hl, vl, "┌┐└┘─│");
+  }
+  return nccells_ascii_box(n, attr, channels, ul, ur, ll, lr, hl, vl);
+}
+
+static inline int
+nccells_heavy_box(struct ncplane* n, uint32_t attr, uint64_t channels,
+                  nccell* ul, nccell* ur, nccell* ll, nccell* lr, nccell* hl, nccell* vl){
+  if(notcurses_canutf8(ncplane_notcurses(n))){
+    return nccells_load_box(n, attr, channels, ul, ur, ll, lr, hl, vl, "┏┓┗┛━┃");
+  }
+  return nccells_ascii_box(n, attr, channels, ul, ur, ll, lr, hl, vl);
+}
+
 static inline int
 ncplane_rounded_box(struct ncplane* n, uint32_t styles, uint64_t channels,
                     int ystop, int xstop, unsigned ctlword){

src/lib/notcurses.c

@@ -2821,16 +2821,6 @@ char* ncplane_contents(ncplane* nc, int begy, int begx, int leny, int lenx){
   return ret;
 }
 
-int nccells_ascii_box(ncplane* n, uint32_t attr, uint64_t channels,
-                      nccell* ul, nccell* ur, nccell* ll, nccell* lr, nccell* hl, nccell* vl){
-  return nccells_load_box(n, attr, channels, ul, ur, ll, lr, hl, vl, "/\\\\/-|");
-}
-
-int cells_ascii_box(ncplane* n, uint32_t attr, uint64_t channels,
-                    nccell* ul, nccell* ur, nccell* ll, nccell* lr, nccell* hl, nccell* vl){
-  return nccells_ascii_box(n, attr, channels, ul, ur, ll, lr, hl, vl);
-}
-
 int nccells_double_box(ncplane* n, uint32_t attr, uint64_t channels,
                        nccell* ul, nccell* ur, nccell* ll, nccell* lr, nccell* hl, nccell* vl){
   if(notcurses_canutf8(ncplane_notcurses(n))){