Gets the index and relative place in the collection that an object is being dropped over.
capi
drop-object-collection-index drop-object => index, placement
(setf (drop-object-collection-index drop-object) (values new-index new-placement))
drop-object⇩ |
A drop-object, as passed to the drop-callback. |
new-index⇩ |
An integer. |
new-placement⇩ |
One of :above , :item or :below . |
index⇩ |
An integer. |
placement⇩ |
One of :above , :item or :below . |
The accessor drop-object-collection-index
accesses 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 the values new-index and new-placement 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:
(example-edit-file "capi/choice/drag-and-drop")
CAPI User Guide and Reference Manual (Unix version) - 01 Dec 2021 19:32:42