I just create a dialog-based project in MFC (VS2008) and add OnKeyDown
event to the dialog.
When I run the project and press the keys on the keyboard, nothing happens. But, if I remove all the controls from the dialog and rerun the project it works.
What should I do to get key events even when I have controls on the dialog?
Here's a piece of code:
void CgDlg::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
// TODO: Add your message handler code here and/or call default
AfxMessageBox(L"Key down!");
CDialog::OnKeyDown(nChar, nRepCnt, nFlags);
}
When a dialog has controls on it, the dialog itself never gets the focus. It's stolen by the child controls. When you press a button, a WM_KEYDOWN
message is sent to the control with focus so your CgDlg::OnKeyDown
is never called. Override the dialog's PreTranslateMessage
function if you want dialog to handle the WM_KEYDOWN
message:
BOOL CgDlg::PreTranslateMessage(MSG* pMsg)
{
if(pMsg->message == WM_KEYDOWN )
{
if(pMsg->wParam == VK_DOWN)
{
...
}
else if(pMsg->wParam == ...)
{
...
}
...
else
{
...
}
}
return CDialog::PreTranslateMessage(pMsg);
}
Also see this article on CodeProject: http://www.codeproject.com/KB/dialog/pretransdialog01.aspx
Many of my CDialog apps use OnKeyDown(). As long you only want to receive key presses and draw on the screen (as in make a game), delete the default buttons and static text (the CDialog must be empty) and OnKeyDown() will start working. Once controls are placed on the CDialog, OnKeyDown() will no longer be called.