Re: Drag N Drop Woes

From: Robert (noone_at_nowhere.com)
Date: 04/30/04 

Date: Fri, 30 Apr 2004 09:11:47 +0200

Hi,

are you using the DragOver and DragDrop events? Take a look at the
OLEDrag... events, they offer a lot more functionality. That way you'll have
more control when to display which cursor, and you'll know from the
OLEDragCompleted event when a drag was completed (or canceled)

And what kinds of widgets do you have?

Robert

"Joseph Geretz" <jgeretz@nospam.com> wrote in message
news:ex1uVUYLEHA.1272@tk2msftngp13.phx.gbl...
> I haven't done a whole lot of drag and drop so maybe I'm missing something
> obvious.
>
> Let's say I have 25 widgets on my application form. That's not a lot.
Let's
> say also that one of these widgets is the source of a drag-n-drop, and one
> is a legitimate target onto which it can be dropped. The source widget is
in
> Manual mode. Starting the drag is no big deal. A module level variable
> tracks the mouse down state for the control (MouseDown, MouseUp); if a
> MouseMove event occurs while the mouse is down then SourceWidget.Drag
starts
> the drag operation.
>
> Starting the drag operation is no big deal. It's ending it which seems to
be
> a real pain. Although the application will only process the drop if
dropped
> on a particular TargetWidget, the user might drop the SourceWidget
anywhere
> on the screen. This means that in order to know when the user has
completed
> the drag, I need to implement every single DragDrop event handler for
every
> single widget on the form? This is a development / maintenance nightmare!
>
> And what about changing the icon? We start off with the default drag icon,
> but as the icon is dragged over it's drop zone, I'd like to morph the icon
> to indicate that it can be dropped here. OK, that's easy enough, simply
> replace the DragIcon in the DragOver event handler of the TargetWidget.
But
> now the user moves off the drop zone without dropping. Now I need to
change
> the icon back. So again, do I have to place code into the DragOver event
> handler of every widget on the form to make sure that the correct icon is
> showed while the object is dragged over that region? (Technically, I'd
only
> have to implement the handler for those widgets which border on the drop
> zone. But even this is not strictly true. Sometimes a quick mouse move
will
> traverse a small area without triggering a DragOver.) Again, a development
/
> maintenance nightmare!
>
> It gets worse. In this primitive example, I cited 25 widgets and one Drag
> source. In my scenario, we're more likely talking about three separate
drag
> sources, with 2 different icons for each, depending on whether the object
is
> over the drop zone or not. And between all frames, buttons, checkboxes,
text
> boxes, etc., I have a heck of a lot more than 25 widgets on this
particular
> form.
>
> Please tell me I'm missing something. It can't really be as cumbersome as
it
> seems. Can it?
>
> Please say it ain't so! Thanks for your help,
>
> - Joe Geretz -
>
>