[input] provide utf8 form in ncinput

NEWS.md

@@ -35,6 +35,9 @@ rearrangements of Notcurses.
   * `CELL_TRIVIAL_INITIALIZER`, `CELL_CHAR_INITIALIZER`, and
     `CELL_INITIALIZER` are all now prefixed with `NC`.
   * A new resize callback, `ncplane_resize_placewithin()`, has been added.
+  * The `ncinput` struct has a new field, `utf8`. `notcurses_get()` will fill
+    in this array of `char` with the NUL-terminated UTF-8 representation of
+    the input whenever one exists.
 
 * 2.4.9 (2021-11-11)
   * Added `ncnmetric()`, which uses `snprintf()` internally. `ncmetric()`

doc/man/man3/notcurses_input.3.md

@@ -18,6 +18,7 @@ typedef struct ncinput {
   uint32_t id;     // Unicode codepoint
   int y;           // Y cell coordinate of event, -1 for undefined
   int x;           // X cell coordinate of event, -1 for undefined
+  char utf8[5];    // utf8 representation, when one exists
   bool alt;        // Was Alt held during the event?
   bool shift;      // Was Shift held during the event?
   bool ctrl;       // Was Ctrl held during the event?
@@ -69,6 +70,8 @@ must be explicitly enabled via **notcurses_mice_enable**. The full 32-bit
 range of Unicode is supported (see **unicode(7)**), with synthesized events
 mapped above the 1,114,112 codepoints of Unicode 14.0's seventeen Planes.
 Unicode characters are returned directly as UCS-32, one codepoint at a time.
+When the input has a UTF8 representation, it is written to **utf8**; this
+field is always NUL-terminated.
 
 notcurses takes its keyboard input from **stdin**, which will be placed into
 non-blocking mode for the duration of operation. The terminal is put into

include/notcurses/notcurses.h

@@ -1065,6 +1065,7 @@ nckey_mouse_p(uint32_t r){
 typedef struct ncinput {
   uint32_t id;       // Unicode codepoint or synthesized NCKEY event
   int y, x;          // y/x cell coordinate of event, -1 for undefined
+  char utf8[5];      // utf8 representation, if one exists
   bool alt;          // was alt held?
   bool shift;        // was shift held?
   bool ctrl;         // was ctrl held?

src/input/input.cpp

@@ -346,7 +346,7 @@ int input_demo(ncpp::NotCurses* nc) {
         }
       }else{
         n->set_fg_rgb8(64, 128, 250);
-        n->printf("Unicode: [0x%08x] '%lc'", r, (wchar_t)r);
+        n->printf("Unicode: [0x%08x] '%s'", r, ni.utf8);
       }
     }
     unsigned x;

src/lib/in.c

@@ -2220,6 +2220,10 @@ internal_get(inputctx* ictx, const struct timespec* ts, ncinput* ni){
   uint32_t id;
   if(ictx->drain){
     logerror("input is being drained\n");
+    if(ni){
+      memset(ni, 0, sizeof(*ni));
+      ni->id = (uint32_t)-1;
+    }
     return (uint32_t)-1;
   }
   pthread_mutex_lock(&ictx->ilock);
@@ -2239,9 +2243,16 @@ internal_get(inputctx* ictx, const struct timespec* ts, ncinput* ni){
       int r = pthread_cond_timedwait(&ictx->icond, &ictx->ilock, ts);
       if(r == ETIMEDOUT){
         pthread_mutex_unlock(&ictx->ilock);
+        if(ni){
+          memset(ni, 0, sizeof(*ni));
+        }
         return 0;
       }else if(r < 0){
         inc_input_errors(ictx);
+        if(ni){
+          memset(ni, 0, sizeof(*ni));
+          ni->id = (uint32_t)-1;
+        }
         return (uint32_t)-1;
       }
     }
@@ -2249,6 +2260,9 @@ internal_get(inputctx* ictx, const struct timespec* ts, ncinput* ni){
   id = ictx->inputs[ictx->iread].id;
   if(ni){
     memcpy(ni, &ictx->inputs[ictx->iread], sizeof(*ni));
+    if(notcurses_ucs32_to_utf8(&ni->id, 1, (unsigned char*)ni->utf8, sizeof(ni->utf8)) < 0){
+      ni->utf8[0] = 0;
+    }
   }
   if(++ictx->iread == ictx->isize){
     ictx->iread = 0;
@@ -2278,14 +2292,8 @@ internal_get(inputctx* ictx, const struct timespec* ts, ncinput* ni){
 
 // infp has already been set non-blocking
 uint32_t notcurses_get(notcurses* nc, const struct timespec* absdl, ncinput* ni){
-  uint32_t id = internal_get(nc->tcache.ictx, absdl, ni);
-  if(ni){
-    if(id == (uint32_t)-1){
-      ni->id = id;
-    }
-  }
-  logdebug("returning 0x%08x\n", id);
-  return id;
+  uint32_t ret = internal_get(nc->tcache.ictx, absdl, ni);
+  return ret;
 }
 
 // FIXME better performance if we move this within the locked area