add ncdirect_canopen_images() and ncdirect_canutf8() #753

USAGE.md

@@ -364,6 +364,13 @@ nc_err_e ncdirect_render_image(struct ncdirect* nc, const char* filename,
                                ncblitter_e blitter, ncscale_e scale);
 ```
 
+Several of the Notcurses capability predicates have `ncdirect` analogues:
+
+```c
+bool ncdirect_canopen_images(const struct ncdirect* n);
+bool ncdirect_canutf8(const struct ncdirect* n);
+```
+
 ## Alignment
 
 Most functions that generate output can be aligned relative to an ncplane.

doc/man/man3/notcurses_directmode.3.md

@@ -56,6 +56,10 @@ ncdirect_init - minimal notcurses instances for styling text
 
 **int ncdirect_putstr(struct ncdirect* nc, uint64_t channels, const char* utf8);**
 
+**bool ncdirect_canopen_images(const struct ncdirect* n);**
+
+**bool ncdirect_canutf8(const struct ncdirect* n);**
+
 **nc_err_e ncdirect_render_image(struct ncdirect* n, const char* filename, ncblitter_e blitter, ncscale_e scale);**
 
 # DESCRIPTION

include/notcurses/direct.h

@@ -96,8 +96,11 @@ API nc_err_e ncdirect_render_image(struct ncdirect* n, const char* filename,
 // Clear the screen.
 API int ncdirect_clear(struct ncdirect* nc);
 
-// Release 'nc' and any associated resources. 0 on success, non-0 on failure.
+// Can we load images? This requires being built against FFmpeg/OIIO.
-API int ncdirect_stop(struct ncdirect* nc);
+API bool ncdirect_canopen_images(const struct ncdirect* n);
+
+// Is our encoding UTF-8? Requires LANG being set to a UTF8 locale.
+API bool ncdirect_canutf8(const struct ncdirect* n);
 
 // Draw horizontal/vertical lines using the specified channels, interpolating
 // between them as we go. The EGC may not use more than one column. For a
@@ -109,6 +112,9 @@ API int ncdirect_hline_interp(struct ncdirect* n, const char* egc, int len,
 API int ncdirect_vline_interp(struct ncdirect* n, const char* egc, int len,
                               uint64_t h1, uint64_t h2);
 
+// Release 'nc' and any associated resources. 0 on success, non-0 on failure.
+API int ncdirect_stop(struct ncdirect* nc);
+
 #undef API
 
 #ifdef __cplusplus

python/src/notcurses/build_notcurses.py

@@ -503,6 +503,8 @@ int ncdirect_cursor_right(struct ncdirect* nc, int num);
 int ncdirect_cursor_down(struct ncdirect* nc, int num);
 int ncdirect_hline_interp(struct ncdirect* n, const char* egc, int len, uint64_t h1, uint64_t h2);
 int ncdirect_vline_interp(struct ncdirect* n, const char* egc, int len, uint64_t h1, uint64_t h2);
+bool ncdirect_canopen_images(const struct ncdirect* n);
+bool ncdirect_canutf8(const struct ncdirect* n);
 nc_err_e ncdirect_render_image(struct ncdirect* n, const char* filename, ncalign_e align, ncblitter_e blitter, ncscale_e scale);
 """)
 

src/lib/direct.cpp

@@ -651,3 +651,21 @@ int ncdirect_vline_interp(ncdirect* n, const char* egc, int len,
   }
   return ret;
 }
+
+// Can we load images? This requires being built against FFmpeg/OIIO.
+bool ncdirect_canopen_images(const ncdirect* n){
+  (void)n;
+#ifdef USE_FFMPEG
+  return true;
+#else
+#ifdef USE_OIIO
+  return true;
+#endif
+#endif
+  return false;
+}
+
+// Is our encoding UTF-8? Requires LANG being set to a UTF8 locale.
+bool ncdirect_canutf8(const ncdirect* n){
+  return n->utf8;
+}

src/poc/vizdirect.c

@@ -12,6 +12,10 @@ int main(void){
   if((n = ncdirect_init(NULL, stdout)) == NULL){
     return EXIT_FAILURE;
   }
+  if(!ncdirect_canopen_images(n)){
+    fprintf(stderr, "This notcurses was not build with multimedia support.\n");
+    return EXIT_FAILURE;
+  }
   if(ncdirect_render_image(n, "../data/normal.png", NCALIGN_LEFT,
                            NCBLIT_DEFAULT, NCSCALE_STRETCH) != NCERR_SUCCESS){
     return EXIT_FAILURE;