edu.northwestern.at.utils.swing
Class ListDropTargetOnItem

java.lang.Object
  edu.northwestern.at.utils.swing.XDropTarget
      edu.northwestern.at.utils.swing.ListDropTargetOnItem

All Implemented Interfaces:

java.awt.dnd.DropTargetListener, java.util.EventListener

public abstract class ListDropTargetOnItem
extends XDropTarget

An abstract base class for JList drop targets where the targets are the list elements.

This base class is appropriate for use in situations where drops are on elements rather than between them.

As the user moves the mouse over the list, the cell under the mouse is hilighted by outlining it and painting over it with translucent green. Only "valid" target cells are hilighted. The concrete subclass must implement the targetIsValid method to make the decision about which cells are valid targets.

Thanks to the superclass XDropTarget lists autoscroll during drags.

Constructor Summary

ListDropTargetOnItem(javax.swing.JList list, javax.swing.JScrollPane scrollPane)
Constructs a new list drop target.

Method Summary

abstract void	acceptDrop(int targetIndex, java.awt.dnd.DropTargetDropEvent dtde) Accepts a drop on a target.
void	dragExit(java.awt.dnd.DropTargetEvent dte) Handles drag exit events.
void	dragOver(java.awt.dnd.DropTargetDragEvent dtde) Handles drag over events.
void	drop(java.awt.dnd.DropTargetDropEvent dtde) Handles drop events.
int	getScrollIncrement(boolean up) Gets the scroll increment for autoscrolling.
void	stopDrag() Stops a drag.
abstract boolean	targetIsValid(int targetIndex, java.util.List flavors) Returns true if a target cell is valid.

Methods inherited from class edu.northwestern.at.utils.swing.XDropTarget

dragEnter, dropActionChanged, setGhost, stopCurrentTarget

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ListDropTargetOnItem

public ListDropTargetOnItem(javax.swing.JList list,
                            javax.swing.JScrollPane scrollPane)

Constructs a new list drop target.

Parameters:

list - The list.

scrollPane - The scroll pane if the list is scrollable, else null.

Method Detail

getScrollIncrement

public int getScrollIncrement(boolean up)

Gets the scroll increment for autoscrolling.

Specified by:

getScrollIncrement in class XDropTarget

Parameters:

up - True if scrolling up, false if scrolling down.

stopDrag

public void stopDrag()

Stops a drag.

Overrides:

stopDrag in class XDropTarget

dragExit

public void dragExit(java.awt.dnd.DropTargetEvent dte)

Handles drag exit events.

Specified by:

dragExit in interface java.awt.dnd.DropTargetListener

Overrides:

dragExit in class XDropTarget

Parameters:

dte - The event.

dragOver

public void dragOver(java.awt.dnd.DropTargetDragEvent dtde)

Handles drag over events.

Specified by:

dragOver in interface java.awt.dnd.DropTargetListener

Overrides:

dragOver in class XDropTarget

Parameters:

dtde - The event.

drop

public void drop(java.awt.dnd.DropTargetDropEvent dtde)

Handles drop events.

Specified by:

drop in interface java.awt.dnd.DropTargetListener

Specified by:

drop in class XDropTarget

Parameters:

dtde - The event.

targetIsValid

public abstract boolean targetIsValid(int targetIndex,
                                      java.util.List flavors)

Returns true if a target cell is valid.

Parameters:

targetIndex - The target cell index.

flavors - A list of the data flavors in the drag source.

Returns:

True if target cell is valid, false otherwise.

acceptDrop

public abstract void acceptDrop(int targetIndex,
                                java.awt.dnd.DropTargetDropEvent dtde)

Accepts a drop on a target.

Parameters:

targetIndex - The target cell index on which the drop occurred.

dtde - The drop target drop event.