public class

DragSourceContext

extends Object
implements DragSourceListener DragSourceMotionListener Serializable
java.lang.Object
   ↳ java.awt.dnd.DragSourceContext

Class Overview

The DragSourceContext class is responsible for managing the initiator side of the Drag and Drop protocol. In particular, it is responsible for managing drag event notifications to the DragSourceListeners and DragSourceMotionListeners, and providing the Transferable representing the source data for the drag operation.

Note that the DragSourceContext itself implements the DragSourceListener and DragSourceMotionListener interfaces. This is to allow the platform peer (the DragSourceContextPeer instance) created by the DragSource to notify the DragSourceContext of state changes in the ongoing operation. This allows the DragSourceContext to interpose itself between the platform and the listeners provided by the initiator of the drag operation.

See Also

Summary

Constants
int CHANGED An int used by updateCurrentCursor() indicating that the user operation has changed.
int DEFAULT An int used by updateCurrentCursor() indicating that the Cursor should change to the default (no drop) Cursor.
int ENTER An int used by updateCurrentCursor() indicating that the Cursor has entered a DropTarget.
int OVER An int used by updateCurrentCursor() indicating that the Cursor is over a DropTarget.
Public Constructors
DragSourceContext(DragSourceContextPeer dscp, DragGestureEvent trigger, Cursor dragCursor, Image dragImage, Point offset, Transferable t, DragSourceListener dsl)
Called from DragSource, this constructor creates a new DragSourceContext given the DragSourceContextPeer for this Drag, the DragGestureEvent that triggered the Drag, the initial Cursor to use for the Drag, an (optional) Image to display while the Drag is taking place, the offset of the Image origin from the hotspot at the instant of the triggering event, the Transferable subject data, and the DragSourceListener to use during the Drag and Drop operation.
Public Methods
synchronized void addDragSourceListener(DragSourceListener dsl)
Add a DragSourceListener to this DragSourceContext if one has not already been added.
void dragDropEnd(DragSourceDropEvent dsde)
Calls dragDropEnd on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDropEvent.
void dragEnter(DragSourceDragEvent dsde)
Calls dragEnter on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent.
void dragExit(DragSourceEvent dse)
Calls dragExit on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceEvent.
void dragMouseMoved(DragSourceDragEvent dsde)
Calls dragMouseMoved on the DragSourceMotionListeners registered with the DragSource associated with this DragSourceContext, and them passes the specified DragSourceDragEvent.
void dragOver(DragSourceDragEvent dsde)
Calls dragOver on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent.
void dropActionChanged(DragSourceDragEvent dsde)
Calls dropActionChanged on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent.
Component getComponent()
Returns the Component associated with this DragSourceContext.
Cursor getCursor()
Returns the current drag Cursor.
DragSource getDragSource()
Returns the DragSource that instantiated this DragSourceContext.
int getSourceActions()
Returns a bitwise mask of DnDConstants that represent the set of drop actions supported by the drag source for the drag operation associated with this DragSourceContext.
Transferable getTransferable()
Returns the Transferable associated with this DragSourceContext.
DragGestureEvent getTrigger()
Returns the DragGestureEvent that initially triggered the drag.
synchronized void removeDragSourceListener(DragSourceListener dsl)
Removes the specified DragSourceListener from this DragSourceContext.
synchronized void setCursor(Cursor c)
Sets the cursor for this drag operation to the specified Cursor.
void transferablesFlavorsChanged()
Notifies the peer that the Transferable's DataFlavors have changed.
Protected Methods
synchronized void updateCurrentCursor(int sourceAct, int targetAct, int status)
If the default drag cursor behavior is active, this method sets the default drag cursor for the specified actions supported by the drag source, the drop target action, and status, otherwise this method does nothing.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.awt.dnd.DragSourceListener
From interface java.awt.dnd.DragSourceMotionListener

Constants

protected static final int CHANGED

An int used by updateCurrentCursor() indicating that the user operation has changed.

Constant Value: 3 (0x00000003)

protected static final int DEFAULT

An int used by updateCurrentCursor() indicating that the Cursor should change to the default (no drop) Cursor.

Constant Value: 0 (0x00000000)

protected static final int ENTER

An int used by updateCurrentCursor() indicating that the Cursor has entered a DropTarget.

Constant Value: 1 (0x00000001)

protected static final int OVER

An int used by updateCurrentCursor() indicating that the Cursor is over a DropTarget.

Constant Value: 2 (0x00000002)

Public Constructors

public DragSourceContext (DragSourceContextPeer dscp, DragGestureEvent trigger, Cursor dragCursor, Image dragImage, Point offset, Transferable t, DragSourceListener dsl)

Called from DragSource, this constructor creates a new DragSourceContext given the DragSourceContextPeer for this Drag, the DragGestureEvent that triggered the Drag, the initial Cursor to use for the Drag, an (optional) Image to display while the Drag is taking place, the offset of the Image origin from the hotspot at the instant of the triggering event, the Transferable subject data, and the DragSourceListener to use during the Drag and Drop operation.
If DragSourceContextPeer is null NullPointerException is thrown.
If DragGestureEvent is null NullPointerException is thrown.
If Cursor is null no exception is thrown and the default drag cursor behavior is activated for this drag operation.
If Image is null no exception is thrown.
If Image is not null and the offset is null NullPointerException is thrown.
If Transferable is null NullPointerException is thrown.
If DragSourceListener is null no exception is thrown.

Parameters
dscp the DragSourceContextPeer for this drag
trigger the triggering event
dragCursor the initial Cursor
dragImage the Image to drag (or null)
offset the offset of the image origin from the hotspot at the instant of the triggering event
t the Transferable
dsl the DragSourceListener
Throws
IllegalArgumentException if the Component associated with the trigger event is null.
IllegalArgumentException if the DragSource for the trigger event is null.
IllegalArgumentException if the drag action for the trigger event is DnDConstants.ACTION_NONE.
IllegalArgumentException if the source actions for the DragGestureRecognizer associated with the trigger event are equal to DnDConstants.ACTION_NONE.
NullPointerException if dscp, trigger, or t are null, or if dragImage is non-null and offset is null

Public Methods

public synchronized void addDragSourceListener (DragSourceListener dsl)

Add a DragSourceListener to this DragSourceContext if one has not already been added. If a DragSourceListener already exists, this method throws a TooManyListenersException.

Parameters
dsl the DragSourceListener to add. Note that while null is not prohibited, it is not acceptable as a parameter.

Throws
if a DragSourceListener has already been added
TooManyListenersException

public void dragDropEnd (DragSourceDropEvent dsde)

Calls dragDropEnd on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDropEvent.

Parameters
dsde the DragSourceDropEvent

public void dragEnter (DragSourceDragEvent dsde)

Calls dragEnter on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent.

Parameters
dsde the DragSourceDragEvent

public void dragExit (DragSourceEvent dse)

Calls dragExit on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceEvent.

Parameters
dse the DragSourceEvent

public void dragMouseMoved (DragSourceDragEvent dsde)

Calls dragMouseMoved on the DragSourceMotionListeners registered with the DragSource associated with this DragSourceContext, and them passes the specified DragSourceDragEvent.

Parameters
dsde the DragSourceDragEvent

public void dragOver (DragSourceDragEvent dsde)

Calls dragOver on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent.

Parameters
dsde the DragSourceDragEvent

public void dropActionChanged (DragSourceDragEvent dsde)

Calls dropActionChanged on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent.

Parameters
dsde the DragSourceDragEvent

public Component getComponent ()

Returns the Component associated with this DragSourceContext.

Returns
  • the Component that started the drag

public Cursor getCursor ()

Returns the current drag Cursor.

Returns
  • the current drag Cursor

public DragSource getDragSource ()

Returns the DragSource that instantiated this DragSourceContext.

Returns
  • the DragSource that instantiated this DragSourceContext

public int getSourceActions ()

Returns a bitwise mask of DnDConstants that represent the set of drop actions supported by the drag source for the drag operation associated with this DragSourceContext.

Returns
  • the drop actions supported by the drag source

public Transferable getTransferable ()

Returns the Transferable associated with this DragSourceContext.

Returns
  • the Transferable

public DragGestureEvent getTrigger ()

Returns the DragGestureEvent that initially triggered the drag.

Returns
  • the Event that triggered the drag

public synchronized void removeDragSourceListener (DragSourceListener dsl)

Removes the specified DragSourceListener from this DragSourceContext.

Parameters
dsl the DragSourceListener to remove; note that while null is not prohibited, it is not acceptable as a parameter

public synchronized void setCursor (Cursor c)

Sets the cursor for this drag operation to the specified Cursor. If the specified Cursor is null, the default drag cursor behavior is activated for this drag operation, otherwise it is deactivated.

Parameters
c the Cursor to display, or null to activate the default drag cursor behavior

public void transferablesFlavorsChanged ()

Notifies the peer that the Transferable's DataFlavors have changed.

Protected Methods

protected synchronized void updateCurrentCursor (int sourceAct, int targetAct, int status)

If the default drag cursor behavior is active, this method sets the default drag cursor for the specified actions supported by the drag source, the drop target action, and status, otherwise this method does nothing.

Parameters
sourceAct the actions supported by the drag source
targetAct the drop target action
status one of the fields DEFAULT, ENTER, OVER, CHANGED