Implement SDL_GetKeyName (#22921)

I found this pretty useful during debugging recently.

Author: sbc100

src/library_sdl.js

@@ -1767,9 +1767,16 @@ var LibrarySDL = {
   SDL_GetKeyState: () => _SDL_GetKeyboardState(0),
 
   SDL_GetKeyName__proxy: 'sync',
-  SDL_GetKeyName__deps: ['$stringToNewUTF8'],
+  SDL_GetKeyName__deps: ['$stringToUTF8', 'realloc'],
   SDL_GetKeyName: (key) => {
-    SDL.keyName ||= stringToNewUTF8('unknown key');
+    var name = '';
+    /* ASCII A-Z or 0-9 */
+    if ((key >= 97 && key <= 122) || (key >= 48 && key <= 57)) {
+      name = String.fromCharCode(key);
+    }
+    var size = lengthBytesUTF8(name) + 1;
+    SDL.keyName = _realloc(SDL.keyName, size);
+    stringToUTF8(name, SDL.keyName, size);
     return SDL.keyName;
   },
 

test/browser/test_sdl_key_test.c

@@ -7,8 +7,9 @@
 
 #include <stdio.h>
 #include <SDL/SDL.h>
-#include <SDL/SDL_ttf.h>
+#ifdef __EMSCRIPTEN__
 #include <emscripten.h>
+#endif
 
 int result = 1;
 
@@ -21,13 +22,13 @@ void one() {
       case SDL_KEYDOWN:
         if (!keys[event.key.keysym.sym]) {
           keys[event.key.keysym.sym] = 1;
-          printf("key down: sym %d scancode %d\n", event.key.keysym.sym, event.key.keysym.scancode);
+          printf("key down: sym=%d scancode=%d name=%s\n", event.key.keysym.sym, event.key.keysym.scancode, SDL_GetKeyName(event.key.keysym.sym));
         }
         break;
       case SDL_KEYUP:
         if (keys[event.key.keysym.sym]) {
           keys[event.key.keysym.sym] = 0;
-          printf("key up: sym %d scancode %d\n", event.key.keysym.sym, event.key.keysym.scancode);
+          printf("key up: sym=%d scancode=%d name=%s\n", event.key.keysym.sym, event.key.keysym.scancode, SDL_GetKeyName(event.key.keysym.sym));
         }
         break;
     }
@@ -40,7 +41,11 @@ int main(int argc, char **argv) {
   SDL_Init(SDL_INIT_VIDEO);
   SDL_Surface *screen = SDL_SetVideoMode(600, 450, 32, SDL_HWSURFACE);
 
+#if __EMSCRIPTEN__
   emscripten_set_main_loop(one, 0, 0);
+#else
+  while (1) one();
+#endif
 
   return 0;
 }

test/test_other.py

@@ -2392,6 +2392,28 @@ def test_sdl_scan_code_from_key(self):
     ''')
     self.do_runf('main.c', '204\n')
 
+  def test_sdl_get_key_name(self):
+    create_file('main.c', r'''
+      #include <stdio.h>
+      #include <SDL/SDL_keyboard.h>
+
+      int main() {
+        printf("a -> '%s'\n", SDL_GetKeyName(SDLK_a));
+        printf("z -> '%s'\n", SDL_GetKeyName(SDLK_z));
+        printf("0 -> '%s'\n", SDL_GetKeyName(SDLK_0));
+        printf("0 -> '%s'\n", SDL_GetKeyName(SDLK_9));
+        printf("F1 -> '%s'\n", SDL_GetKeyName(SDLK_F1));
+        return 0;
+      }
+    ''')
+    self.do_runf('main.c', '''\
+a -> 'a'
+z -> 'z'
+0 -> '0'
+0 -> '9'
+F1 -> ''
+''')
+
   @requires_network
   def test_sdl2_mixer_wav(self):
     self.emcc(test_file('browser/test_sdl2_mixer_wav.c'), ['-sUSE_SDL_MIXER=2'], output_filename='a.out.js')