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4/14/2010

You can easily extend the program-key associated behavior of your application. This topic uses an example application called testkeys ( testkeys.exe) to demonstrate the following tasks:

To determine which program key is currently assigned to testkeys and to register that keyboard shortcut when testkeys.exe starts

  • The message handler for WM_CREATEis a convenient place for the following code.

    Note:
    The call to the Windows Embedded CE function RegisterHotKeyuses MOD_WINas the keyboard shortcut modifier because the hardware keys all send MOD_WINwith their key code.
    Copy Code 
    BYTE appkey;
appkey = SHGetAppKeyAssoc(_T("testkeys.exe"));
if (appkey != 0)
{
	if (!RegisterHotKey(hWnd, 400, MOD_WIN, appkey)) 
	{
		// Can't register keyboard shortcut.
		MessageBox(NULL, _T("Can't register hotkey."),
						 _T("Warning"), MB_OK);
		exit(0);  // Replace with specific error handling.
}
}

To check whether your application is in the foreground and to bring it to the foreground if it is not

  • The following example assumes you are handling the WM_HOTKEYmessage as part of the WndProcmethod used to handle Windows messages.

    Note:
    You also need code to perform any special action, such as changing views, based on pressing the keyboard shortcut.
    Copy Code 
    case WM_HOTKEY:
	switch(wParam)
	{
		case 400:
	// This is the keyboard shortcut you registered.
	// Is the application in the foreground?
	if (hWnd != GetForegroundWindow())
	{
	// No, bring it forward and that is all.
	// Set focus to foremost child window.
	// The "| 0x01" is used to bring any owned 
	// windows to the foreground and open them.
	SetForegroundWindow((HWND)((ULONG) hWnd | 0x00000001));
}
	else
	{
	// Already on top, so take an action.
	MessageBox(hWnd, _T("Hotkey Pressed"), 
					 _T("Hotkey"), MB_OK);
}
	break;

To release the program key back to the shell

  • When the application closes, it should call UnregisterHotkeyto release the program key back to the shell, as shown in the following example.

    Copy Code 
    	case WM_DESTROY:
		appkey = SHGetAppKeyAssoc(_T("testkeys.exe"));
		if (appkey != 0)
		{
			if(!UnregisterHotKey(hWnd, 400)) 
		{
			// Can't unregister hotkey.
			MessageBox(NULL, _T("Can't unregister hotkey"),
							 _T("Warning"), MB_OK);
			exit(0);  // Replace with specific error handling.
	}
}

See Also