Friggin' Windows remaps alphabetic keys based on keyboard layout.

We try to figure out what the actual layout independent values are.

src/video/win32/SDL_win32events.c

@@ -54,17 +54,12 @@ RemapVKEY(WPARAM wParam, LPARAM lParam)
        We try to provide USB scancodes, so undo this mapping.
      */
     if (wParam >= 'A' && wParam <= 'Z') {
-        /* Alphabetic scancodes for PC keyboards */
-        static BYTE scancodes[26] = {
-            30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38, 50, 49, 24,
-            25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44
-        };
         BYTE scancode = (lParam >> 16) & 0xFF;
         int i;
 
-        if (scancode != scancodes[wParam - 'A']) {
-            for (i = 0; i < SDL_arraysize(scancodes); ++i) {
-                if (scancode == scancodes[i]) {
+        if (scancode != alpha_scancodes[wParam - 'A']) {
+            for (i = 0; i < SDL_arraysize(alpha_scancodes); ++i) {
+                if (scancode == alpha_scancodes[i]) {
                     wParam = 'A' + i;
                     break;
                 }
@@ -448,6 +443,12 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
         }
         return (0);
 
+    case WM_INPUTLANGCHANGE:
+        {
+            WIN_UpdateKeymap(data->videodata->keyboard);
+        }
+        return (1);
+
     case WM_GETMINMAXINFO:
         {
             MINMAXINFO *info;

src/video/win32/SDL_win32keyboard.c

@@ -26,27 +26,52 @@
 #include "../../events/SDL_keyboard_c.h"
 #include "../../events/scancodes_win32.h"
 
+#ifndef MAPVK_VK_TO_VSC
+#define MAPVK_VK_TO_VSC     0
+#endif
+#ifndef MAPVK_VSC_TO_VK
+#define MAPVK_VSC_TO_VK     1
+#endif
+#ifndef MAPVK_VK_TO_CHAR
+#define MAPVK_VK_TO_CHAR    2
+#endif
+
+/* Alphabetic scancodes for PC keyboards */
+BYTE alpha_scancodes[26] = {
+    30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38, 50, 49, 24,
+    25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44
+};
+
 void
 WIN_InitKeyboard(_THIS)
 {
     SDL_VideoData *data = (SDL_VideoData *) _this->driverdata;
     SDL_Keyboard keyboard;
+    int i;
+
+    /* Make sure the alpha scancodes are correct.  T isn't usually remapped */
+    if (MapVirtualKey('T', MAPVK_VK_TO_VSC) != alpha_scancodes['T'-'A']) {
+printf("Fixing alpha scancode map, assuming US QWERTY layout!\nPlease send the following 26 lines of output to the SDL mailing list <sdl@libsdl.org>, including a description of your keyboard hardware.\n");
+        for (i = 0; i < SDL_arraysize(alpha_scancodes); ++i) {
+            alpha_scancodes[i] = MapVirtualKey('A'+i, MAPVK_VK_TO_VSC);
+printf("%d = %d\n", i, alpha_scancodes[i]);
+        }
+    }
 
     data->key_layout = win32_scancode_table;
 
     SDL_zero(keyboard);
     data->keyboard = SDL_AddKeyboard(&keyboard, -1);
-    WIN_UpdateKeymap(_this);
+    WIN_UpdateKeymap(data->keyboard);
 
     SDL_SetScancodeName(SDL_SCANCODE_APPLICATION, "Menu");
     SDL_SetScancodeName(SDL_SCANCODE_LGUI, "Left Windows");
     SDL_SetScancodeName(SDL_SCANCODE_RGUI, "Right Windows");
 }
 
 void
-WIN_UpdateKeymap(_THIS)
+WIN_UpdateKeymap(int keyboard)
 {
-    SDL_VideoData *data = (SDL_VideoData *) _this->driverdata;
     int i;
     SDL_scancode scancode;
     SDLKey keymap[SDL_NUM_SCANCODES];
@@ -61,12 +86,16 @@ WIN_UpdateKeymap(_THIS)
             (keymap[scancode] & SDLK_SCANCODE_MASK)) {
             continue;
         }
-#ifndef MAPVK_VK_TO_CHAR
-#define MAPVK_VK_TO_CHAR    2
-#endif
-        keymap[scancode] = (MapVirtualKey(i, MAPVK_VK_TO_CHAR) & 0x7FFF);
+
+        /* Alphabetic keys are handled specially, since Windows remaps them */
+        if (i >= 'A' && i <= 'Z') {
+            BYTE vsc = alpha_scancodes[i-'A'];
+            keymap[scancode] = MapVirtualKey(vsc, MAPVK_VSC_TO_VK) + 0x20;
+        } else {
+            keymap[scancode] = (MapVirtualKey(i, MAPVK_VK_TO_CHAR) & 0x7FFF);
+        }
     }
-    SDL_SetKeymap(data->keyboard, 0, keymap, SDL_NUM_SCANCODES);
+    SDL_SetKeymap(keyboard, 0, keymap, SDL_NUM_SCANCODES);
 }
 
 void

src/video/win32/SDL_win32keyboard.h

@@ -24,8 +24,10 @@
 #ifndef _SDL_win32keyboard_h
 #define _SDL_win32keyboard_h
 
+extern BYTE alpha_scancodes[26];
+
 extern void WIN_InitKeyboard(_THIS);
-extern void WIN_UpdateKeymap(_THIS);
+extern void WIN_UpdateKeymap(int keyboard);
 extern void WIN_QuitKeyboard(_THIS);
 
 #endif /* _SDL_win32keyboard_h */