File	Doc	Category	Size	Date	Package
DragSourceContext.java	API Doc	Java SE 5 API	20715	Fri Aug 26 14:56:48 BST 2005	java.awt.dnd

DragSourceContext

• java.lang.Object

Fields Summary
private static final long	serialVersionUID
protected static final int	DEFAULT An int used by updateCurrentCursor() indicating that the Cursor should change to the default (no drop) Cursor.
protected static final int	ENTER An int used by updateCurrentCursor() indicating that the Cursor has entered a DropTarget.
protected static final int	OVER An int used by updateCurrentCursor() indicating that the Cursor is over a DropTarget.
protected static final int	CHANGED An int used by updateCurrentCursor() indicating that the user operation has changed.
private static Transferable	emptyTransferable
private transient DragSourceContextPeer	peer
private DragGestureEvent	trigger The event which triggered the start of the drag.
private Cursor	cursor The current drag cursor.
private transient Transferable	transferable
private transient DragSourceListener	listener
private boolean	useCustomCursor true if the custom drag cursor is used instead of the default one.
private final int	sourceActions A bitwise mask of DnDConstants that represents the set of drop actions supported by the drag source for the drag operation associated with this DragSourceContext.

Constructors Summary

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. param dscp the DragSourceContextPeer for this drag param trigger the triggering event param dragCursor the initial Cursor param dragImage the Image to drag (or null) param offset the offset of the image origin from the hotspot at the instant of the triggering event param t the Transferable param dsl the DragSourceListener throws IllegalArgumentException if the Component associated with the trigger event is null. throws IllegalArgumentException if the DragSource for the trigger event is null. throws IllegalArgumentException if the drag action for the trigger event is DnDConstants.ACTION_NONE. throws IllegalArgumentException if the source actions for the DragGestureRecognizer associated with the trigger event are equal to DnDConstants.ACTION_NONE. throws NullPointerException if dscp, trigger, or t are null, or if dragImage is non-null and offset is null if (dscp == null) { throw new NullPointerException("DragSourceContextPeer"); } if (trigger == null) { throw new NullPointerException("Trigger"); } if (trigger.getDragSource() == null) { throw new IllegalArgumentException("DragSource"); } if (trigger.getComponent() == null) { throw new IllegalArgumentException("Component"); } if (trigger.getSourceAsDragGestureRecognizer().getSourceActions() == DnDConstants.ACTION_NONE) { throw new IllegalArgumentException("source actions"); } if (trigger.getDragAction() == DnDConstants.ACTION_NONE) { throw new IllegalArgumentException("no drag action"); } if (t == null) { throw new NullPointerException("Transferable"); } if (dragImage != null && offset == null) { throw new NullPointerException("offset"); } peer = dscp; this.trigger = trigger; cursor = dragCursor; transferable = t; listener = dsl; sourceActions = trigger.getSourceAsDragGestureRecognizer().getSourceActions(); useCustomCursor = (dragCursor != null); updateCurrentCursor(trigger.getDragAction(), getSourceActions(), DEFAULT);

Methods Summary
public synchronized void	addDragSourceListener(java.awt.dnd.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. param dsl the DragSourceListener to add. Note that while null is not prohibited, it is not acceptable as a parameter. throws TooManyListenersException if a DragSourceListener has already been added if (dsl == null) return; if (equals(dsl)) throw new IllegalArgumentException("DragSourceContext may not be its own listener"); if (listener != null) throw new TooManyListenersException(); else listener = dsl;
public void	dragDropEnd(java.awt.dnd.DragSourceDropEvent dsde) Calls dragDropEnd on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDropEvent. param dsde the DragSourceDropEvent DragSourceListener dsl = listener; if (dsl != null) { dsl.dragDropEnd(dsde); } getDragSource().processDragDropEnd(dsde);
public void	dragEnter(java.awt.dnd.DragSourceDragEvent dsde) Calls dragEnter on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent. param dsde the DragSourceDragEvent DragSourceListener dsl = listener; if (dsl != null) { dsl.dragEnter(dsde); } getDragSource().processDragEnter(dsde); updateCurrentCursor(dsde.getDropAction(), dsde.getTargetActions(), ENTER);
public void	dragExit(java.awt.dnd.DragSourceEvent dse) Calls dragExit on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceEvent. param dse the DragSourceEvent DragSourceListener dsl = listener; if (dsl != null) { dsl.dragExit(dse); } getDragSource().processDragExit(dse); updateCurrentCursor(DnDConstants.ACTION_NONE, DnDConstants.ACTION_NONE, DEFAULT);
public void	dragMouseMoved(java.awt.dnd.DragSourceDragEvent dsde) Calls dragMouseMoved on the DragSourceMotionListeners registered with the DragSource associated with this DragSourceContext, and them passes the specified DragSourceDragEvent. param dsde the DragSourceDragEvent since 1.4 getDragSource().processDragMouseMoved(dsde);
public void	dragOver(java.awt.dnd.DragSourceDragEvent dsde) Calls dragOver on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent. param dsde the DragSourceDragEvent DragSourceListener dsl = listener; if (dsl != null) { dsl.dragOver(dsde); } getDragSource().processDragOver(dsde); updateCurrentCursor(dsde.getDropAction(), dsde.getTargetActions(), OVER);
public void	dropActionChanged(java.awt.dnd.DragSourceDragEvent dsde) Calls dropActionChanged on the DragSourceListeners registered with this DragSourceContext and with the associated DragSource, and passes them the specified DragSourceDragEvent. param dsde the DragSourceDragEvent DragSourceListener dsl = listener; if (dsl != null) { dsl.dropActionChanged(dsde); } getDragSource().processDropActionChanged(dsde); updateCurrentCursor(dsde.getDropAction(), dsde.getTargetActions(), CHANGED);
public java.awt.Component	getComponent() Returns the Component associated with this DragSourceContext. return the Component that started the drag return trigger.getComponent();
public java.awt.Cursor	getCursor() Returns the current drag Cursor. return the current drag Cursor return cursor;
public java.awt.dnd.DragSource	getDragSource() Returns the DragSource that instantiated this DragSourceContext. return the DragSource that instantiated this DragSourceContext return trigger.getDragSource();
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. return the drop actions supported by the drag source return sourceActions;
public java.awt.datatransfer.Transferable	getTransferable() Returns the Transferable associated with this DragSourceContext. return the Transferable return transferable;
public java.awt.dnd.DragGestureEvent	getTrigger() Returns the DragGestureEvent that initially triggered the drag. return the Event that triggered the drag return trigger;
private void	readObject(java.io.ObjectInputStream s) Deserializes this DragSourceContext. This method first performs default deserialization for all non-transient fields. This object's Transferable and DragSourceListener are then deserialized as well by using the next two objects in the stream. If the resulting Transferable is null, this object's Transferable is set to a dummy Transferable which supports no DataFlavors. since 1.4 s.defaultReadObject(); transferable = (Transferable)s.readObject(); listener = (DragSourceListener)s.readObject(); // Implementation assumes 'transferable' is never null. if (transferable == null) { if (emptyTransferable == null) { emptyTransferable = new Transferable() { public DataFlavor[] getTransferDataFlavors() { return new DataFlavor[0]; } public boolean isDataFlavorSupported(DataFlavor flavor) { return false; } public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException { throw new UnsupportedFlavorException(flavor); } }; } transferable = emptyTransferable; }
public synchronized void	removeDragSourceListener(java.awt.dnd.DragSourceListener dsl) Removes the specified DragSourceListener from this DragSourceContext. param dsl the DragSourceListener to remove; note that while null is not prohibited, it is not acceptable as a parameter if (listener != null && listener.equals(dsl)) { listener = null; } else throw new IllegalArgumentException();
public synchronized void	setCursor(java.awt.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. param c the Cursor to display, or null to activate the default drag cursor behavior useCustomCursor = (c != null); setCursorImpl(c);
private void	setCursorImpl(java.awt.Cursor c) if (cursor == null || !cursor.equals(c)) { cursor = c; if (peer != null) peer.setCursor(cursor); }
public void	transferablesFlavorsChanged() Notifies the peer that the Transferable's DataFlavors have changed. if (peer != null) peer.transferablesFlavorsChanged();
protected synchronized void	updateCurrentCursor(int dropOp, int targetAct, int status) If the default drag cursor behavior is active, this method sets the default drag cursor for the specified selected operation, supported actions and status, otherwise this method does nothing. param dropOp the user's currently selected operation param targetAct the current target's supported actions param status the constant // if the cursor has been previously set then dont do any defaults // processing. if (useCustomCursor) { return; } // do defaults processing Cursor c = null; switch (status) { default: targetAct = DnDConstants.ACTION_NONE; case ENTER: case OVER: case CHANGED: int ra = dropOp & targetAct; if (ra == DnDConstants.ACTION_NONE) { // no drop possible if ((dropOp & DnDConstants.ACTION_LINK) == DnDConstants.ACTION_LINK) c = DragSource.DefaultLinkNoDrop; else if ((dropOp & DnDConstants.ACTION_MOVE) == DnDConstants.ACTION_MOVE) c = DragSource.DefaultMoveNoDrop; else c = DragSource.DefaultCopyNoDrop; } else { // drop possible if ((ra & DnDConstants.ACTION_LINK) == DnDConstants.ACTION_LINK) c = DragSource.DefaultLinkDrop; else if ((ra & DnDConstants.ACTION_MOVE) == DnDConstants.ACTION_MOVE) c = DragSource.DefaultMoveDrop; else c = DragSource.DefaultCopyDrop; } } setCursorImpl(c);
private void	writeObject(java.io.ObjectOutputStream s) Serializes this DragSourceContext. This method first performs default serialization. Next, this object's Transferable is written out if and only if it can be serialized. If not, null is written instead. In this case, a DragSourceContext created from the resulting deserialized stream will contain a dummy Transferable which supports no DataFlavors. Finally, this object's DragSourceListener is written out if and only if it can be serialized. If not, null is written instead. serialData The default serializable fields, in alphabetical order, followed by either a Transferable instance, or null, followed by either a DragSourceListener instance, or null. since 1.4 s.defaultWriteObject(); s.writeObject(SerializationTester.test(transferable) ? transferable : null); s.writeObject(SerializationTester.test(listener) ? listener : null);