Drag and drop adapters The hierarchy of drag and drop adapter classes is the following: Class hierarchy Responsibility EwDragAndDropAdapter Defines common behavior for all adapters EwSourceAdapter Defines common behavior for all drag and drop sources EwBlockSourceAdapter Defines a drag and drop source that uses an application-defined block to determine the drag source items EwContainerListSourceAdapter Defines a source adapter for EW container- style widgets EwIconAreaSourceAdapter Defines a source adapter for EwIconArea widgets EwDrawnListSourceAdapter Defines a source adapter for EwDrawnList widgets EwTargetAdapter Defines common behavior for all drag and drop targets EwContainerListTargetAdapter Defines a target adapter for EW container-style widgets EwIconAreaTargetAdapter Defines a target adapter for EwIconArea widgets The Drag and Drop subsystem provides two kinds of adapters for use in drag and drop: source adapters and target adapters. The adapters serve as a wrapper around widgets, providing drag and drop callbacks that the widgets themselves do not provide. An application should create a source adapter for each widget that an application designates as a drag and drop source. An application creates one source adapter for each source widget as follows: aSourceAdapter := EwSourceAdapter on: aWidget. The source adapter provides the following callbacks for drag and drop source operations: dragStartCallback A drag has been started from the source widget. dragChangeCallback The target or semantics of the drag have changed. dragCompleteCallback The drag and drop operation has completed. dragCancelCallback The drag and drop operation was canceled or did not complete. The application also should create a target adapter for each widget that is to be a target for drag and drop. The target adapter is created as follows: aTargetAdapter := EwTargetAdapter on: aWidget The target adapter provides the following callbacks for drag and drop target operations: dragOverCallback The mouse pointer is moving over the drag target widget. dragLeaveCallback The mouse pointer has left the drag target widget. dropCallback The drop operation was indicated over the drag target widget. dragCancelCallback The drag and drop operation was canceled or did not complete.
