Change Selection in CListCtrl when Arrow Keys are pressed

[maglite]

Hi.

I have a CListCtrl in a modal Dialog. The control has the following styles:

- Report
- Single Selection
- No Scroll
- No Sort Header
- Always Show Selection
- Grid Lines
- Full Row Selection

In OnInitDialog I select the first line (Item) and save the selection in the variable m_nItem. So far so good. Selecting items via mouse click and saving the selection also works fine:

void CMyDlg::OnNMClickMyList(NMHDR *pNMHDR, LRESULT *pResult)
{
	LPNMITEMACTIVATE temp = reinterpret_cast<LPNMITEMACTIVATE>(pNMHDR);

	if(temp->iItem == -1) // redundant as in my case only selectable items are visible
		return;
	m_nItem = temp->iItem;
	*pResult = 0;
}

Now I want to programatically change the selection when either the Up or Down Key is pressed and go back to the first item when the list's end is reached (and also the other way round).

So this is my code for handling the LVN_KEYDOWN message:

void CMyDlg::OnLvnKeydownMyList(NMHDR *pNMHDR, LRESULT *pResult)
{
	LPNMLVKEYDOWN pLVKeyDow = reinterpret_cast<LPNMLVKEYDOWN>(pNMHDR);
	
	switch(pLVKeyDow->wVKey)
	{
	case VK_DOWN:
		m_nItem = (m_nItem+1)&#37;m_nItemCount;
		m_ctrlList.SetItemState(m_nItem, LVIS_SELECTED|LVIS_FOCUSED, LVIS_SELECTED|LVIS_FOCUSED);
		break;
	case VK_UP:
		m_nItem = (m_nItem-1+m_nItemCount)%m_nItemCount;
		m_ctrlList.SetItemState(m_nItem, LVIS_SELECTED|LVIS_FOCUSED, LVIS_SELECTED|LVIS_FOCUSED);
		break;
	}
	*pResult = 0;
}

I debugged the code and m_nItem is actually calculated correctly but the wrong item gets selected nevertheless. It seems like - instead of going up/down one item - steps of two items are taken.

I've tried to leave out the LVIS_FOCUS flags and the control showed a different behaviour. Not a more satisfying one though. Still wrong selections from time to time.

Furthermore i tried various combinations of RedrawItems, Invalidate and UpdateWindow after SetItemState, which all seemed to have no effect whatsoever.

I'm pretty clueless. Please Help!

Thanks in advance,
Markus

[Arjay]

By default, don't the up/down arrows change the selection?

I mean isn't this the behavior if you just put a listview control on the page and add some items to it? After the selecting an item, the up/down arrows should work without any additional code.

[maglite]

I tried it and you're right. That explains a lot :-S Thank you. I would've wasted a couple more hours on this...
This way though the selection doesn't "jump" to the first item when pressing the down arrow and the last item is selected. Maybe i can at least handle that case in OnLvnKey....

[Arjay]

This way though the selection doesn't "jump" to the first item when pressing the down arrow and the last item is selected. Maybe i can at least handle that case in OnLvnKey....

You could, but this isn't standard Windows behavior. You'll notice for example, that a list of files in Windows Explorer doesn't wrap when you down arrow and reach the bottom.