Win32: Fix key names not matching other platforms

This brings printable key names more in line with the results provided
on other platforms.

Fixes #943.

README.md

@@ -193,6 +193,7 @@ information on what to include when reporting a bug.
 - [Win32] Bugfix: `glfw3native.h` would undefine a foreign `APIENTRY` (#1062)
 - [Win32] Bugfix: Disabled cursor mode prevented use of caption buttons
                   (#650,#1071)
+- [Win32] Bugfix: Returned key names did not match other platforms (#943)
 - [X11] Moved to XI2 `XI_RawMotion` for disable cursor mode motion input (#125)
 - [X11] Replaced `_GLFW_HAS_XF86VM` compile-time option with dynamic loading
 - [X11] Bugfix: `glfwGetVideoMode` would segfault on Cygwin/X

src/win32_init.c

@@ -429,6 +429,60 @@ void _glfwInputErrorWin32(int error, const char* description)
     _glfwInputError(error, "%s: %s", description, message);
 }
 
+// Updates key names according to the current keyboard layout
+//
+void _glfwUpdateKeyNamesWin32(void)
+{
+    int key;
+    BYTE state[256] = {0};
+
+    memset(_glfw.win32.keynames, 0, sizeof(_glfw.win32.keynames));
+
+    for (key = GLFW_KEY_SPACE;  key <= GLFW_KEY_LAST;  key++)
+    {
+        UINT vk;
+        int scancode, length;
+        WCHAR chars[16];
+
+        scancode = _glfw.win32.scancodes[key];
+        if (scancode == -1)
+            continue;
+
+        if (key >= GLFW_KEY_KP_0 && key <= GLFW_KEY_KP_ADD)
+        {
+            const UINT vks[] = {
+                VK_NUMPAD0,  VK_NUMPAD1,  VK_NUMPAD2, VK_NUMPAD3,
+                VK_NUMPAD4,  VK_NUMPAD5,  VK_NUMPAD6, VK_NUMPAD7,
+                VK_NUMPAD8,  VK_NUMPAD9,  VK_DECIMAL, VK_DIVIDE,
+                VK_MULTIPLY, VK_SUBTRACT, VK_ADD
+            };
+
+            vk = vks[key - GLFW_KEY_KP_0];
+        }
+        else
+            vk = MapVirtualKey(scancode, MAPVK_VSC_TO_VK);
+
+        length = ToUnicode(vk, scancode, state,
+                           chars, sizeof(chars) / sizeof(WCHAR),
+                           0);
+
+        if (length == -1)
+        {
+            length = ToUnicode(vk, scancode, state,
+                               chars, sizeof(chars) / sizeof(WCHAR),
+                               0);
+        }
+
+        if (length < 1)
+            continue;
+
+        WideCharToMultiByte(CP_UTF8, 0, chars, 1,
+                            _glfw.win32.keynames[key],
+                            sizeof(_glfw.win32.keynames[key]),
+                            NULL, NULL);
+    }
+}
+
 
 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW platform API                      //////
@@ -448,6 +502,7 @@ int _glfwPlatformInit(void)
         return GLFW_FALSE;
 
     createKeyTables();
+    _glfwUpdateKeyNamesWin32();
 
     if (_glfw_SetProcessDpiAwareness)
         _glfw_SetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE);

src/win32_platform.h

@@ -250,9 +250,9 @@ typedef struct _GLFWlibraryWin32
     DWORD               foregroundLockTimeout;
     int                 acquiredMonitorCount;
     char*               clipboardString;
-    char                keyName[64];
     short int           keycodes[512];
     short int           scancodes[GLFW_KEY_LAST + 1];
+    char                keynames[GLFW_KEY_LAST + 1][5];
     // Where to place the cursor when re-enabled
     double              restoreCursorPosX, restoreCursorPosY;
     // The window whose disabled cursor mode is active
@@ -353,6 +353,7 @@ void _glfwUnregisterWindowClassWin32(void);
 WCHAR* _glfwCreateWideStringFromUTF8Win32(const char* source);
 char* _glfwCreateUTF8FromWideStringWin32(const WCHAR* source);
 void _glfwInputErrorWin32(int error, const char* description);
+void _glfwUpdateKeyNamesWin32(void);
 
 void _glfwInitTimerWin32(void);
 

src/win32_window.c

@@ -584,6 +584,12 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
             return 0;
         }
 
+        case WM_INPUTLANGCHANGE:
+        {
+            _glfwUpdateKeyNamesWin32();
+            break;
+        }
+
         case WM_CHAR:
         case WM_SYSCHAR:
         case WM_UNICHAR:
@@ -1652,20 +1658,7 @@ void _glfwPlatformSetCursorMode(_GLFWwindow* window, int mode)
 
 const char* _glfwPlatformGetScancodeName(int scancode)
 {
-    WCHAR name[16];
+    return _glfw.win32.keynames[_glfw.win32.keycodes[scancode]];
-
-    if (!GetKeyNameTextW(scancode << 16, name, sizeof(name) / sizeof(WCHAR)))
-        return NULL;
-
-    if (!WideCharToMultiByte(CP_UTF8, 0, name, -1,
-                             _glfw.win32.keyName,
-                             sizeof(_glfw.win32.keyName),
-                             NULL, NULL))
-    {
-        return NULL;
-    }
-
-    return _glfw.win32.keyName;
 }
 
 int _glfwPlatformGetKeyScancode(int key)