Gets the index and relative place in the collection that an object is being dropped over.
drop-object-collection-index drop-object => index , placement
(setf (drop-object-collection-index drop-object ) (values new-index new-placement ))
A drop-object , as passed to the drop-callback .
An integer.
One of
:above
,
:item
or
:below
.
The function
drop-object-collection-index
returns the index and place relative to that index within the collection that the object
drop-object
is being dropped over. This information is only meaningful when the pane is an instance of list-panel or tree-view.
The returned value index is the position in the collection (see get-collection-item or choice-selection). The returned value placement indicates whether the user is dropping above, on or below the item at index .
There is also a setf expander that can be called with these two values within the
:drag
stage of the operation, to adjust where the user will be allowed to drop the object.
drop-object-collection-index
should only be called within a
drop-callback
. It is not supported on X11/Motif. See simple-pane for information about drop callbacks.
For an example illustrating the use of drag and drop in a choice, see
examples/capi/choices/drag-and-drop.lisp