Monday, August 10, 2009

Item Activation

I'm still not sure how this is going to end, but right now items can be focused, selected and activated. An item gets the focus when you use the arrow keys to navigate the list and that is meant to mean the "current" item in the list. When you select an item it gets added to a selection list (in case you need to use multiple-selection lists). Note that focus does not mean selection nor selection means focus. Finally, an activated item is the one you just "pressed" or clicked.

The code I'm publishing today shows how to set the focus on a particular item (just added a highlighter to the DrawItem method) by navigating the list with the arrow keys and how it can be activated by directly clicking it or by pressing the enter key on the focused item.

I had to make some changes to the CTouchWindow class template in order to make sure that scrolling (or flicking through) the list does not get confused with a click. If you hook the application with Remote Spy you will see an interesting pattern of messages when clicking an item: WM_LBUTTONDOWN, WM_MOUSEMOVE (may occur more than once) and WM_LBUTTONUP. What's interesting is that the "mouse move" message always shows up even if it reports the same screen position as the "button down" message. Is this a bug, Microsoft? Anyway, the code already handles null movements so...

When an item is selected, the CCrypSafeView::OnItemChangedState method is called by the base class and to handle the item activation you must handle the TLN_ITEMACTIVATED code. Just take a look at the sample code to see how it is done. Note that you test nmtl.dwState for nonzero meaning activation - it is zero when the item is "deactivated".

Sample code: (325 KB - now includes the OleDbClient lib)


vincent said...

Today I have received a WM6.5 device and I can see that now it uses Touch controls that look like your WTL touchlist. Have you collaborated with MS ?

João Paulo Figueira said...

I take that as a compliment! If I had collaborated with MS, they would not have allowed me to show the source code, would they? ;-)