java.awt.dnd
class DragSourceContext

java.lang.Object java.awt.dnd.DragSourceContext

All Implemented Interfaces:

DragSourceListener, DragSourceMotionListener, Serializable

Most common way to construct:

DragSourceDragEvent e = …;

DragSourceContext ctx = e.getDragSourceContext();

Based on 14 examples

public class DragSourceContext
extends Object
implements DragSourceListener, DragSourceMotionListener, Serializable

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.

CHANGED

protected static final int CHANGED

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

DEFAULT

protected static final int DEFAULT

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

ENTER

protected static final int ENTER

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

OVER

protected static final int OVER

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

DragSourceContext

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

addDragSourceListener

public synchronized void addDragSourceListener(DragSourceListener dsl)
                                        throws TooManyListenersException

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:

TooManyListenersException

dragDropEnd

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

dragEnter

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

dragExit

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

dragMouseMoved

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

dragOver

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

dropActionChanged

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

getComponent

public Component getComponent()

Returns the Component associated with this DragSourceContext.

Returns:

the Component that started the drag

getCursor

public Cursor getCursor()

Returns the current drag Cursor.

Returns:

the current drag Cursor

getDragSource

public DragSource getDragSource()

Returns the DragSource that instantiated this DragSourceContext.

Returns:

the DragSource that instantiated this DragSourceContext

getSourceActions

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

getTransferable

public Transferable getTransferable()

Returns the Transferable associated with this DragSourceContext.

Returns:

the Transferable

getTrigger

public DragGestureEvent getTrigger()

Returns the DragGestureEvent that initially triggered the drag.

Returns:

the Event that triggered the drag

removeDragSourceListener

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

setCursor

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

transferablesFlavorsChanged

public void transferablesFlavorsChanged()

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

updateCurrentCursor

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