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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;}