dragsourcecontext.java

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    }

    /**
     * Notifies the peer that the <code>Transferable</code>'s
     * <code>DataFlavor</code>s have changed.
     */

    public void transferablesFlavorsChanged() {
	if (peer != null) peer.transferablesFlavorsChanged();
    }

    /**
     * Calls <code>dragEnter</code> on the
     * <code>DragSourceListener</code>s registered with this
     * <code>DragSourceContext</code> and with the associated
     * <code>DragSource</code>, and passes them the specified
     * <code>DragSourceDragEvent</code>.
     *
     * @param dsde the <code>DragSourceDragEvent</code>
     */
    public void dragEnter(DragSourceDragEvent dsde) {
        DragSourceListener dsl = listener;
        if (dsl != null) {
            dsl.dragEnter(dsde);
        }
        getDragSource().processDragEnter(dsde);

	updateCurrentCursor(dsde.getDropAction(), dsde.getTargetActions(), ENTER);
    }

    /**
     * Calls <code>dragOver</code> on the
     * <code>DragSourceListener</code>s registered with this
     * <code>DragSourceContext</code> and with the associated
     * <code>DragSource</code>, and passes them the specified
     * <code>DragSourceDragEvent</code>.
     *
     * @param dsde the <code>DragSourceDragEvent</code>
     */
    public void dragOver(DragSourceDragEvent dsde) {
        DragSourceListener dsl = listener;
        if (dsl != null) {
            dsl.dragOver(dsde);
        }
        getDragSource().processDragOver(dsde);

	updateCurrentCursor(dsde.getDropAction(), dsde.getTargetActions(), OVER);
    }

    /**
     * Calls <code>dragExit</code> on the
     * <code>DragSourceListener</code>s registered with this
     * <code>DragSourceContext</code> and with the associated
     * <code>DragSource</code>, and passes them the specified
     * <code>DragSourceEvent</code>.
     *
     * @param dse the <code>DragSourceEvent</code>
     */
    public void dragExit(DragSourceEvent dse) {
        DragSourceListener dsl = listener;
        if (dsl != null) {
            dsl.dragExit(dse);
        }
        getDragSource().processDragExit(dse);

	updateCurrentCursor(DnDConstants.ACTION_NONE, DnDConstants.ACTION_NONE, DEFAULT);
    }

    /**
     * Calls <code>dropActionChanged</code> on the
     * <code>DragSourceListener</code>s registered with this
     * <code>DragSourceContext</code> and with the associated
     * <code>DragSource</code>, and passes them the specified
     * <code>DragSourceDragEvent</code>.
     *
     * @param dsde the <code>DragSourceDragEvent</code>
     */
    public void dropActionChanged(DragSourceDragEvent dsde) {
        DragSourceListener dsl = listener;
        if (dsl != null) {
            dsl.dropActionChanged(dsde);
        }
        getDragSource().processDropActionChanged(dsde);

	updateCurrentCursor(dsde.getDropAction(), dsde.getTargetActions(), CHANGED);
    }

    /**
     * Calls <code>dragDropEnd</code> on the
     * <code>DragSourceListener</code>s registered with this
     * <code>DragSourceContext</code> and with the associated
     * <code>DragSource</code>, and passes them the specified
     * <code>DragSourceDropEvent</code>.
     *
     * @param dsde the <code>DragSourceDropEvent</code>
     */
    public void dragDropEnd(DragSourceDropEvent dsde) {
        DragSourceListener dsl = listener;
        if (dsl != null) {
            dsl.dragDropEnd(dsde);
        }
        getDragSource().processDragDropEnd(dsde);
    }

    /**
     * Calls <code>dragMouseMoved</code> on the
     * <code>DragSourceMotionListener</code>s registered with the
     * <code>DragSource</code> associated with this
     * <code>DragSourceContext</code>, and them passes the specified
     * <code>DragSourceDragEvent</code>.
     *
     * @param dsde the <code>DragSourceDragEvent</code>
     * @since 1.4
     */
    public void dragMouseMoved(DragSourceDragEvent dsde) {
        getDragSource().processDragMouseMoved(dsde);
    }

    /**
     * Returns the <code>Transferable</code> associated with
     * this <code>DragSourceContext</code>.
     * 
     * @return the <code>Transferable</code>
     */
    public Transferable getTransferable() { return transferable; }
   
    /**
     * 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
     */

    protected synchronized void updateCurrentCursor(int dropOp, int targetAct, int status) {

	// 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 setCursorImpl(Cursor c) {
        if (cursor == null || !cursor.equals(c)) {
            cursor = c;
            if (peer != null) peer.setCursor(cursor);
        }
    }

    /**
     * Serializes this <code>DragSourceContext</code>. This method first
     * performs default serialization. Next, this object's
     * <code>Transferable</code> is written out if and only if it can be
     * serialized. If not, <code>null</code> is written instead. In this case,
     * a <code>DragSourceContext</code> created from the resulting deserialized
     * stream will contain a dummy <code>Transferable</code> which supports no
     * <code>DataFlavor</code>s. Finally, this object's
     * <code>DragSourceListener</code> is written out if and only if it can be
     * serialized. If not, <code>null</code> is written instead.
     *
     * @serialData The default serializable fields, in alphabetical order,
     *             followed by either a <code>Transferable</code> instance, or
     *             <code>null</code>, followed by either a
     *             <code>DragSourceListener</code> instance, or
     *             <code>null</code>.
     * @since 1.4
     */
    private void writeObject(ObjectOutputStream s) throws IOException {
        s.defaultWriteObject();

        s.writeObject(SerializationTester.test(transferable)
                      ? transferable : null);
        s.writeObject(SerializationTester.test(listener)
                      ? listener : null);
    }

    /**
     * Deserializes this <code>DragSourceContext</code>. This method first
     * performs default deserialization for all non-<code>transient</code>
     * fields. This object's <code>Transferable</code> and
     * <code>DragSourceListener</code> are then deserialized as well by using
     * the next two objects in the stream. If the resulting
     * <code>Transferable</code> is <code>null</code>, this object's
     * <code>Transferable</code> is set to a dummy <code>Transferable</code>
     * which supports no <code>DataFlavor</code>s.
     *
     * @since 1.4
     */
    private void readObject(ObjectInputStream s)
        throws ClassNotFoundException, IOException
    {
        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;
        }
    }

    private static Transferable emptyTransferable;

    /*
     * fields
     */

    private transient DragSourceContextPeer peer;

    /**
     * The event which triggered the start of the drag.
     *
     * @serial
     */
    private DragGestureEvent    trigger;

    /**
     * The current drag cursor.
     *
     * @serial
     */
    private Cursor              cursor;

    private transient Transferable      transferable;

    private transient DragSourceListener    listener;

    /**
     * <code>true</code> if the custom drag cursor is used instead of the
     * default one.
     *
     * @serial
     */
    private boolean useCustomCursor;

    /**
     * A bitwise mask of <code>DnDConstants</code> that represents the set of
     * drop actions supported by the drag source for the drag operation associated
     * with this <code>DragSourceContext.</code>  
     *
     * @serial
     */
    private final int sourceActions;
}