While working on an application that requires drag and drop, I ran into trouble when trying to figure out where in the target list (in my case, a ListBox) to insert the dropped item. I ran across Josh Smith's article Drag and Drop Items in a WPF ListView which covers (quite nicely) how to handle drag and drop operations within and between ListViews. While reading through the code, I found that he uses some code from Dan Crevier which was posted on Lester's Blog. Ok, now that I have taken you through the tangled web of other people's code, I will share how I used the code and changed it a little to work in my situation.
public static Point GetMousePosition(Visual relativeTo)
{
Win32Point mouse = new Win32Point();
GetCursorPos(ref mouse);
System.Windows.Interop.HwndSource presentationSource =
(System.Windows.Interop.HwndSource)PresentationSource.FromVisual(relativeTo);
ScreenToClient(presentationSource.Handle, ref mouse);
GeneralTransform transform = relativeTo.TransformToAncestor(presentationSource.RootVisual);
Point offset = transform.Transform(new Point(0, 0));
return new Point(mouse.X - offset.X, mouse.Y - offset.Y);
}
public static int GetIndexUnderDragCursor(ItemsControl control)
{
int index = -1;
for (int i = 0; i < control.Items.Count; ++i)
{
if (control.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
{
DependencyObject item = control.ItemContainerGenerator.ContainerFromIndex(i);
if (IsMouseOver(item as Visual))
{
index = i;
break;
}
}
}
return index;
}
public static bool IsMouseOver(Visual target)
{
if (target == null)
return false;
Rect bounds = VisualTreeHelper.GetDescendantBounds(target);
Point mousePos = GetMousePosition(target);
return bounds.Contains(mousePos);
}
I didn't change the GetMousePosition method at all from what I found on Lester's blog. Then I slightly modified some of Josh's code so that it is a little more general. I hope this helps. Suggestions welcome.
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