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	/*
	* Copyright (c) 1997, 2004, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.awt.dnd;

	import java.awt.Component;

	import java.awt.datatransfer.DataFlavor;
	import java.awt.datatransfer.Transferable;
	import java.awt.datatransfer.UnsupportedFlavorException;

	import java.awt.dnd.peer.DropTargetContextPeer;

	import java.io.IOException;
	import java.io.Serializable;

	import java.util.Arrays;
	import java.util.List;


	/**
	* A <code>DropTargetContext</code> is created
	* whenever the logical cursor associated
	* with a Drag and Drop operation coincides with the visible geometry of
	* a <code>Component</code> associated with a <code>DropTarget</code>.
	* The <code>DropTargetContext</code> provides
	* the mechanism for a potential receiver
	* of a drop operation to both provide the end user with the appropriate
	* drag under feedback, but also to effect the subsequent data transfer
	* if appropriate.
	*
	* @since 1.2
	*/

	public class DropTargetContext implements Serializable {

	private static final long serialVersionUID = -634158968993743371L;

	/**
	* Construct a <code>DropTargetContext</code>
	* given a specified <code>DropTarget</code>.
	* <P>
	* @param dt the DropTarget to associate with
	*/

	DropTargetContext(DropTarget dt) {
	super();

	dropTarget = dt;
	}

	/**
	* This method returns the <code>DropTarget</code> associated with this
	* <code>DropTargetContext</code>.
	* <P>
	* @return the <code>DropTarget</code> associated with this <code>DropTargetContext</code>
	*/

	public DropTarget getDropTarget() { return dropTarget; }

	/**
	* This method returns the <code>Component</code> associated with
	* this <code>DropTargetContext</code>.
	* <P>
	* @return the Component associated with this Context
	*/

	public Component getComponent() { return dropTarget.getComponent(); }

	/**
	* Called when associated with the <code>DropTargetContextPeer</code>.
	* <P>
	* @param dtcp the <code>DropTargetContextPeer</code>
	*/

	public void addNotify(DropTargetContextPeer dtcp) {
	dropTargetContextPeer = dtcp;
	}

	/**
	* Called when disassociated with the <code>DropTargetContextPeer</code>.
	*/

	public void removeNotify() {
	dropTargetContextPeer = null;
	transferable = null;
	}

	/**
	* This method sets the current actions acceptable to
	* this <code>DropTarget</code>.
	* <P>
	* @param actions an <code>int</code> representing the supported action(s)
	*/

	protected void setTargetActions(int actions) {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	if (peer != null) {
	synchronized (peer) {
	peer.setTargetActions(actions);
	getDropTarget().doSetDefaultActions(actions);
	}
	} else {
	getDropTarget().doSetDefaultActions(actions);
	}
	}

	/**
	* This method returns an <code>int</code> representing the
	* current actions this <code>DropTarget</code> will accept.
	* <P>
	* @return the current actions acceptable to this <code>DropTarget</code>
	*/

	protected int getTargetActions() {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	return ((peer != null)
	? peer.getTargetActions()
	: dropTarget.getDefaultActions()
	);
	}

	/**
	* This method signals that the drop is completed and
	* if it was successful or not.
	* <P>
	* @param success true for success, false if not
	* <P>
	* @throws InvalidDnDOperationException if a drop is not outstanding/extant
	*/

	public void dropComplete(boolean success) throws InvalidDnDOperationException{
	DropTargetContextPeer peer = getDropTargetContextPeer();
	if (peer != null) {
	peer.dropComplete(success);
	}
	}

	/**
	* accept the Drag.
	* <P>
	* @param dragOperation the supported action(s)
	*/

	protected void acceptDrag(int dragOperation) {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	if (peer != null) {
	peer.acceptDrag(dragOperation);
	}
	}

	/**
	* reject the Drag.
	*/

	protected void rejectDrag() {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	if (peer != null) {
	peer.rejectDrag();
	}
	}

	/**
	* called to signal that the drop is acceptable
	* using the specified operation.
	* must be called during DropTargetListener.drop method invocation.
	* <P>
	* @param dropOperation the supported action(s)
	*/

	protected void acceptDrop(int dropOperation) {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	if (peer != null) {
	peer.acceptDrop(dropOperation);
	}
	}

	/**
	* called to signal that the drop is unacceptable.
	* must be called during DropTargetListener.drop method invocation.
	*/

	protected void rejectDrop() {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	if (peer != null) {
	peer.rejectDrop();
	}
	}

	/**
	* get the available DataFlavors of the
	* <code>Transferable</code> operand of this operation.
	* <P>
	* @return a <code>DataFlavor[]</code> containing the
	* supported <code>DataFlavor</code>s of the
	* <code>Transferable</code> operand.
	*/

	protected DataFlavor[] getCurrentDataFlavors() {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	return peer != null ? peer.getTransferDataFlavors() : new DataFlavor[0];
	}

	/**
	* This method returns a the currently available DataFlavors
	* of the <code>Transferable</code> operand
	* as a <code>java.util.List</code>.
	* <P>
	* @return the currently available
	* DataFlavors as a <code>java.util.List</code>
	*/

	protected List<DataFlavor> getCurrentDataFlavorsAsList() {
	return Arrays.asList(getCurrentDataFlavors());
	}

	/**
	* This method returns a <code>boolean</code>
	* indicating if the given <code>DataFlavor</code> is
	* supported by this <code>DropTargetContext</code>.
	* <P>
	* @param df the <code>DataFlavor</code>
	* <P>
	* @return if the <code>DataFlavor</code> specified is supported
	*/

	protected boolean isDataFlavorSupported(DataFlavor df) {
	return getCurrentDataFlavorsAsList().contains(df);
	}

	/**
	* get the Transferable (proxy) operand of this operation
	* <P>
	* @throws InvalidDnDOperationException if a drag is not outstanding/extant
	* <P>
	* @return the <code>Transferable</code>
	*/

	protected Transferable getTransferable() throws InvalidDnDOperationException {
	DropTargetContextPeer peer = getDropTargetContextPeer();
	if (peer == null) {
	throw new InvalidDnDOperationException();
	} else {
	if (transferable == null) {
	Transferable t = peer.getTransferable();
	boolean isLocal = peer.isTransferableJVMLocal();
	synchronized (this) {
	if (transferable == null) {
	transferable = createTransferableProxy(t, isLocal);
	}
	}
	}

	return transferable;
	}
	}

	/**
	* Get the <code>DropTargetContextPeer</code>
	* <P>
	* @return the platform peer
	*/

	DropTargetContextPeer getDropTargetContextPeer() {
	return dropTargetContextPeer;
	}

	/**
	* Creates a TransferableProxy to proxy for the specified
	* Transferable.
	*
	* @param t the <tt>Transferable</tt> to be proxied
	* @param local <tt>true</tt> if <tt>t</tt> represents
	* the result of a local drag-n-drop operation.
	* @return the new <tt>TransferableProxy</tt> instance.
	*/
	protected Transferable createTransferableProxy(Transferable t, boolean local) {
	return new TransferableProxy(t, local);
	}

	/****************************************************************************/


	/**
	* <code>TransferableProxy</code> is a helper inner class that implements
	* <code>Transferable</code> interface and serves as a proxy for another
	* <code>Transferable</code> object which represents data transfer for
	* a particular drag-n-drop operation.
	* <p>
	* The proxy forwards all requests to the encapsulated transferable
	* and automatically performs additional conversion on the data
	* returned by the encapsulated transferable in case of local transfer.
	*/

	protected class TransferableProxy implements Transferable {

	/**
	* Constructs a <code>TransferableProxy</code> given
	* a specified <code>Transferable</code> object representing
	* data transfer for a particular drag-n-drop operation and
	* a <code>boolean</code> which indicates whether the
	* drag-n-drop operation is local (within the same JVM).
	* <p>
	* @param t the <code>Transferable</code> object
	* @param local <code>true</code>, if <code>t</code> represents
	* the result of local drag-n-drop operation
	*/
	TransferableProxy(Transferable t, boolean local) {
	proxy = new sun.awt.datatransfer.TransferableProxy(t, local);
	transferable = t;
	isLocal = local;
	}

	/**
	* Returns an array of DataFlavor objects indicating the flavors
	* the data can be provided in by the encapsulated transferable.
	* <p>
	* @return an array of data flavors in which the data can be
	* provided by the encapsulated transferable
	*/
	public DataFlavor[] getTransferDataFlavors() {
	return proxy.getTransferDataFlavors();
	}

	/**
	* Returns whether or not the specified data flavor is supported by
	* the encapsulated transferable.
	* @param flavor the requested flavor for the data
	* @return <code>true</code> if the data flavor is supported,
	* <code>false</code> otherwise
	*/
	public boolean isDataFlavorSupported(DataFlavor flavor) {
	return proxy.isDataFlavorSupported(flavor);
	}

	/**
	* Returns an object which represents the data provided by
	* the encapsulated transferable for the requested data flavor.
	* <p>
	* In case of local transfer a serialized copy of the object
	* returned by the encapsulated transferable is provided when
	* the data is requested in application/x-java-serialized-object
	* data flavor.
	*
	* @param df the requested flavor for the data
	* @throws IOException if the data is no longer available
	* in the requested flavor.
	* @throws UnsupportedFlavorException if the requested data flavor is
	* not supported.
	*/
	public Object getTransferData(DataFlavor df)
	throws UnsupportedFlavorException, IOException
	{
	return proxy.getTransferData(df);
	}

	/*
	* fields
	*/

	// We don't need to worry about client code changing the values of
	// these variables. Since TransferableProxy is a protected class, only
	// subclasses of DropTargetContext can access it. And DropTargetContext
	// cannot be subclassed by client code because it does not have a
	// public constructor.

	/**
	* The encapsulated <code>Transferable</code> object.
	*/
	protected Transferable transferable;

	/**
	* A <code>boolean</code> indicating if the encapsulated
	* <code>Transferable</code> object represents the result
	* of local drag-n-drop operation (within the same JVM).
	*/
	protected boolean isLocal;

	private sun.awt.datatransfer.TransferableProxy proxy;
	}

	/****************************************************************************/

	/*
	* fields
	*/

	/**
	* The DropTarget associated with this DropTargetContext.
	*
	* @serial
	*/
	private DropTarget dropTarget;

	private transient DropTargetContextPeer dropTargetContextPeer;

	private transient Transferable transferable;
	}

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