Key down events in a CView derived class

Hi IssacJones,

well, for simple keystrokes like 'Ctrl-A' easiest is to use the view's default command message handling by adding a new command for this keystroke in the application's accelerator table.

'Tab-A' is not a single keystroke, are you sure you need it and it's not a typo?

To distinguish between keystrokes on numeric keypad you directly have to handle WM_KEYDOWN message - unfortunateley this only can be done within a overridden PreTranslateMessage function since the view doesn't pass unhandled keystroke-messages to a WM_KEYDOWN message handler.

To do so override the PreTranslateMessage function of the view and implement it somehow like this:

> BOOL CTestViewSDIView::PreTranslateMessage(MSG* pMsg)
> {
>       if ( pMsg->message == WM_KEYDOWN )
>       {
>             if ( pMsg->wParam == VK_PRIOR )
>             {
>                  bool bNumPad = ( pMsg->lParam & ( 1 << 24 ) ) == 0; // see MSDN about WM_KEYDOWN for description of extended-key flag
>
>                  TRACE( "PageUp pressed (extended: %s)\n", false == bNumPad ? "false" : "true" );
>
>                  // don't pass it to the view's default message handler as long as you handle it yourself
>                  return TRUE;
>            }
>      }
>
>      return CView::PreTranslateMessage(pMsg);
> }

Hope this helps,

ZOPPO

Hi Zoppo

Many thanks for your help. I didn't explain the "single keystroke" very well. What I was planning to trap was when a user presses Tab and A simultaneously e.g. in a similar manner in Visual Studio you can press Ctrl and Tab at the same time to cycle through files.

Indeed, what I want to do with trapping Tab and A at the same time is to cycle through some views. I thought I'd worked out how to do this but now I suspect I need help with this as well. There are two views that I want to cycle through. Both views are in two seperate functions which I'm going to call  in OnDraw.

Any ideas on how to do it?

John

Hi again,

well, IMo it's quite unusual to combine two keys for a command - CTRL, SHIFT and ALT are treated as some kind of state-modifiers for a pressed key, TAB and A are treated as single keystrokes.

Anyway, it can be done either the way alb66 suggested - see attached code for this ...

ZOPPO

BOOL CTestViewSDIView::PreTranslateMessage(MSG* pMsg)
{
	if ( pMsg->message == WM_KEYDOWN )
	{
		if ( pMsg->wParam == VK_PRIOR )
		{
			bool bNumPad = ( pMsg->lParam & ( 1 << 24 ) ) == 0; // see MSDN about WM_KEYDOWN for description of extended-key flag
 
			TRACE( "PageUp pressed (extended: %s)\n", false == bNumPad ? "false" : "true" );
		}
		else if ( pMsg->wParam == 'A' )
		{
			if ( GetKeyState( VK_TAB ) < 0 )
			{
				TRACE( "A+TAB pressed ...\n" );
			}
		}
 
		// don't pass it to the view's default message handler
		return TRUE;
	}
 
	return CView::PreTranslateMessage(pMsg);
}

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Hi Zoppo

Ah, okay, could I bother you with one final thing, what would be the best way to deal with Ctrl and Tab i.e. the same as the example I gave with Visual Studio?

John

Excellent! I'll allocate points to both of you because I learnt something new from you both.