jdk/src/java.desktop/share/classes/javax/swing/TransferHandler.java
changeset 25859 3317bb8137f4
parent 23010 6dadb192ad81
child 32834 e1dca5fe4de3
child 32865 f9cb6e427f9e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.desktop/share/classes/javax/swing/TransferHandler.java	Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,1796 @@
+/*
+ * Copyright (c) 2000, 2013, 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 javax.swing;
+
+import java.awt.*;
+import java.awt.event.*;
+import java.awt.datatransfer.*;
+import java.awt.dnd.*;
+import java.beans.*;
+import java.lang.reflect.*;
+import java.io.*;
+import java.util.TooManyListenersException;
+import javax.swing.plaf.UIResource;
+import javax.swing.event.*;
+import javax.swing.text.JTextComponent;
+
+import sun.reflect.misc.MethodUtil;
+import sun.swing.SwingUtilities2;
+import sun.awt.AppContext;
+import sun.swing.*;
+import sun.awt.SunToolkit;
+
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+
+import java.security.AccessControlContext;
+import java.security.ProtectionDomain;
+import sun.misc.SharedSecrets;
+import sun.misc.JavaSecurityAccess;
+
+import sun.awt.AWTAccessor;
+
+/**
+ * This class is used to handle the transfer of a <code>Transferable</code>
+ * to and from Swing components.  The <code>Transferable</code> is used to
+ * represent data that is exchanged via a cut, copy, or paste
+ * to/from a clipboard.  It is also used in drag-and-drop operations
+ * to represent a drag from a component, and a drop to a component.
+ * Swing provides functionality that automatically supports cut, copy,
+ * and paste keyboard bindings that use the functionality provided by
+ * an implementation of this class.  Swing also provides functionality
+ * that automatically supports drag and drop that uses the functionality
+ * provided by an implementation of this class.  The Swing developer can
+ * concentrate on specifying the semantics of a transfer primarily by setting
+ * the <code>transferHandler</code> property on a Swing component.
+ * <p>
+ * This class is implemented to provide a default behavior of transferring
+ * a component property simply by specifying the name of the property in
+ * the constructor.  For example, to transfer the foreground color from
+ * one component to another either via the clipboard or a drag and drop operation
+ * a <code>TransferHandler</code> can be constructed with the string "foreground".  The
+ * built in support will use the color returned by <code>getForeground</code> as the source
+ * of the transfer, and <code>setForeground</code> for the target of a transfer.
+ * <p>
+ * Please see
+ * <a href="http://docs.oracle.com/javase/tutorial/uiswing/dnd/index.html">
+ * How to Use Drag and Drop and Data Transfer</a>,
+ * a section in <em>The Java Tutorial</em>, for more information.
+ *
+ *
+ * @author Timothy Prinzing
+ * @author Shannon Hickey
+ * @since 1.4
+ */
+@SuppressWarnings("serial")
+public class TransferHandler implements Serializable {
+
+    /**
+     * An <code>int</code> representing no transfer action.
+     */
+    public static final int NONE = DnDConstants.ACTION_NONE;
+
+    /**
+     * An <code>int</code> representing a &quot;copy&quot; transfer action.
+     * This value is used when data is copied to a clipboard
+     * or copied elsewhere in a drag and drop operation.
+     */
+    public static final int COPY = DnDConstants.ACTION_COPY;
+
+    /**
+     * An <code>int</code> representing a &quot;move&quot; transfer action.
+     * This value is used when data is moved to a clipboard (i.e. a cut)
+     * or moved elsewhere in a drag and drop operation.
+     */
+    public static final int MOVE = DnDConstants.ACTION_MOVE;
+
+    /**
+     * An <code>int</code> representing a source action capability of either
+     * &quot;copy&quot; or &quot;move&quot;.
+     */
+    public static final int COPY_OR_MOVE = DnDConstants.ACTION_COPY_OR_MOVE;
+
+    /**
+     * An <code>int</code> representing a &quot;link&quot; transfer action.
+     * This value is used to specify that data should be linked in a drag
+     * and drop operation.
+     *
+     * @see java.awt.dnd.DnDConstants#ACTION_LINK
+     * @since 1.6
+     */
+    public static final int LINK = DnDConstants.ACTION_LINK;
+
+    /**
+     * An interface to tag things with a {@code getTransferHandler} method.
+     */
+    interface HasGetTransferHandler {
+
+        /** Returns the {@code TransferHandler}.
+         *
+         * @return The {@code TransferHandler} or {@code null}
+         */
+        public TransferHandler getTransferHandler();
+    }
+
+    /**
+     * Represents a location where dropped data should be inserted.
+     * This is a base class that only encapsulates a point.
+     * Components supporting drop may provide subclasses of this
+     * containing more information.
+     * <p>
+     * Developers typically shouldn't create instances of, or extend, this
+     * class. Instead, these are something provided by the DnD
+     * implementation by <code>TransferSupport</code> instances and by
+     * components with a <code>getDropLocation()</code> method.
+     *
+     * @see javax.swing.TransferHandler.TransferSupport#getDropLocation
+     * @since 1.6
+     */
+    public static class DropLocation {
+        private final Point dropPoint;
+
+        /**
+         * Constructs a drop location for the given point.
+         *
+         * @param dropPoint the drop point, representing the mouse's
+         *        current location within the component.
+         * @throws IllegalArgumentException if the point
+         *         is <code>null</code>
+         */
+        protected DropLocation(Point dropPoint) {
+            if (dropPoint == null) {
+                throw new IllegalArgumentException("Point cannot be null");
+            }
+
+            this.dropPoint = new Point(dropPoint);
+        }
+
+        /**
+         * Returns the drop point, representing the mouse's
+         * current location within the component.
+         *
+         * @return the drop point.
+         */
+        public final Point getDropPoint() {
+            return new Point(dropPoint);
+        }
+
+        /**
+         * Returns a string representation of this drop location.
+         * This method is intended to be used for debugging purposes,
+         * and the content and format of the returned string may vary
+         * between implementations.
+         *
+         * @return a string representation of this drop location
+         */
+        public String toString() {
+            return getClass().getName() + "[dropPoint=" + dropPoint + "]";
+        }
+    };
+
+    /**
+     * This class encapsulates all relevant details of a clipboard
+     * or drag and drop transfer, and also allows for customizing
+     * aspects of the drag and drop experience.
+     * <p>
+     * The main purpose of this class is to provide the information
+     * needed by a developer to determine the suitability of a
+     * transfer or to import the data contained within. But it also
+     * doubles as a controller for customizing properties during drag
+     * and drop, such as whether or not to show the drop location,
+     * and which drop action to use.
+     * <p>
+     * Developers typically need not create instances of this
+     * class. Instead, they are something provided by the DnD
+     * implementation to certain methods in <code>TransferHandler</code>.
+     *
+     * @see #canImport(TransferHandler.TransferSupport)
+     * @see #importData(TransferHandler.TransferSupport)
+     * @since 1.6
+     */
+    public final static class TransferSupport {
+        private boolean isDrop;
+        private Component component;
+
+        private boolean showDropLocationIsSet;
+        private boolean showDropLocation;
+
+        private int dropAction = -1;
+
+        /**
+         * The source is a {@code DropTargetDragEvent} or
+         * {@code DropTargetDropEvent} for drops,
+         * and a {@code Transferable} otherwise
+         */
+        private Object source;
+
+        private DropLocation dropLocation;
+
+        /**
+         * Create a <code>TransferSupport</code> with <code>isDrop()</code>
+         * <code>true</code> for the given component, event, and index.
+         *
+         * @param component the target component
+         * @param event a <code>DropTargetEvent</code>
+         */
+        private TransferSupport(Component component,
+                             DropTargetEvent event) {
+
+            isDrop = true;
+            setDNDVariables(component, event);
+        }
+
+        /**
+         * Create a <code>TransferSupport</code> with <code>isDrop()</code>
+         * <code>false</code> for the given component and
+         * <code>Transferable</code>.
+         *
+         * @param component the target component
+         * @param transferable the transferable
+         * @throws NullPointerException if either parameter
+         *         is <code>null</code>
+         */
+        public TransferSupport(Component component, Transferable transferable) {
+            if (component == null) {
+                throw new NullPointerException("component is null");
+            }
+
+            if (transferable == null) {
+                throw new NullPointerException("transferable is null");
+            }
+
+            isDrop = false;
+            this.component = component;
+            this.source = transferable;
+        }
+
+        /**
+         * Allows for a single instance to be reused during DnD.
+         *
+         * @param component the target component
+         * @param event a <code>DropTargetEvent</code>
+         */
+        private void setDNDVariables(Component component,
+                                     DropTargetEvent event) {
+
+            assert isDrop;
+
+            this.component = component;
+            this.source = event;
+            dropLocation = null;
+            dropAction = -1;
+            showDropLocationIsSet = false;
+
+            if (source == null) {
+                return;
+            }
+
+            assert source instanceof DropTargetDragEvent ||
+                   source instanceof DropTargetDropEvent;
+
+            Point p = source instanceof DropTargetDragEvent
+                          ? ((DropTargetDragEvent)source).getLocation()
+                          : ((DropTargetDropEvent)source).getLocation();
+
+            if (SunToolkit.isInstanceOf(component, "javax.swing.text.JTextComponent")) {
+                dropLocation = SwingAccessor.getJTextComponentAccessor().
+                                   dropLocationForPoint((JTextComponent)component, p);
+            } else if (component instanceof JComponent) {
+                dropLocation = ((JComponent)component).dropLocationForPoint(p);
+            }
+
+            /*
+             * The drop location may be null at this point if the component
+             * doesn't return custom drop locations. In this case, a point-only
+             * drop location will be created lazily when requested.
+             */
+        }
+
+        /**
+         * Returns whether or not this <code>TransferSupport</code>
+         * represents a drop operation.
+         *
+         * @return <code>true</code> if this is a drop operation,
+         *         <code>false</code> otherwise.
+         */
+        public boolean isDrop() {
+            return isDrop;
+        }
+
+        /**
+         * Returns the target component of this transfer.
+         *
+         * @return the target component
+         */
+        public Component getComponent() {
+            return component;
+        }
+
+        /**
+         * Checks that this is a drop and throws an
+         * {@code IllegalStateException} if it isn't.
+         *
+         * @throws IllegalStateException if {@code isDrop} is false.
+         */
+        private void assureIsDrop() {
+            if (!isDrop) {
+                throw new IllegalStateException("Not a drop");
+            }
+        }
+
+        /**
+         * Returns the current (non-{@code null}) drop location for the component,
+         * when this {@code TransferSupport} represents a drop.
+         * <p>
+         * Note: For components with built-in drop support, this location
+         * will be a subclass of {@code DropLocation} of the same type
+         * returned by that component's {@code getDropLocation} method.
+         * <p>
+         * This method is only for use with drag and drop transfers.
+         * Calling it when {@code isDrop()} is {@code false} results
+         * in an {@code IllegalStateException}.
+         *
+         * @return the drop location
+         * @throws IllegalStateException if this is not a drop
+         * @see #isDrop()
+         */
+        public DropLocation getDropLocation() {
+            assureIsDrop();
+
+            if (dropLocation == null) {
+                /*
+                 * component didn't give us a custom drop location,
+                 * so lazily create a point-only location
+                 */
+                Point p = source instanceof DropTargetDragEvent
+                              ? ((DropTargetDragEvent)source).getLocation()
+                              : ((DropTargetDropEvent)source).getLocation();
+
+                dropLocation = new DropLocation(p);
+            }
+
+            return dropLocation;
+        }
+
+        /**
+         * Sets whether or not the drop location should be visually indicated
+         * for the transfer - which must represent a drop. This is applicable to
+         * those components that automatically
+         * show the drop location when appropriate during a drag and drop
+         * operation). By default, the drop location is shown only when the
+         * {@code TransferHandler} has said it can accept the import represented
+         * by this {@code TransferSupport}. With this method you can force the
+         * drop location to always be shown, or always not be shown.
+         * <p>
+         * This method is only for use with drag and drop transfers.
+         * Calling it when {@code isDrop()} is {@code false} results
+         * in an {@code IllegalStateException}.
+         *
+         * @param showDropLocation whether or not to indicate the drop location
+         * @throws IllegalStateException if this is not a drop
+         * @see #isDrop()
+         */
+        public void setShowDropLocation(boolean showDropLocation) {
+            assureIsDrop();
+
+            this.showDropLocation = showDropLocation;
+            this.showDropLocationIsSet = true;
+        }
+
+        /**
+         * Sets the drop action for the transfer - which must represent a drop
+         * - to the given action,
+         * instead of the default user drop action. The action must be
+         * supported by the source's drop actions, and must be one
+         * of {@code COPY}, {@code MOVE} or {@code LINK}.
+         * <p>
+         * This method is only for use with drag and drop transfers.
+         * Calling it when {@code isDrop()} is {@code false} results
+         * in an {@code IllegalStateException}.
+         *
+         * @param dropAction the drop action
+         * @throws IllegalStateException if this is not a drop
+         * @throws IllegalArgumentException if an invalid action is specified
+         * @see #getDropAction
+         * @see #getUserDropAction
+         * @see #getSourceDropActions
+         * @see #isDrop()
+         */
+        public void setDropAction(int dropAction) {
+            assureIsDrop();
+
+            int action = dropAction & getSourceDropActions();
+
+            if (!(action == COPY || action == MOVE || action == LINK)) {
+                throw new IllegalArgumentException("unsupported drop action: " + dropAction);
+            }
+
+            this.dropAction = dropAction;
+        }
+
+        /**
+         * Returns the action chosen for the drop, when this
+         * {@code TransferSupport} represents a drop.
+         * <p>
+         * Unless explicitly chosen by way of {@code setDropAction},
+         * this returns the user drop action provided by
+         * {@code getUserDropAction}.
+         * <p>
+         * You may wish to query this in {@code TransferHandler}'s
+         * {@code importData} method to customize processing based
+         * on the action.
+         * <p>
+         * This method is only for use with drag and drop transfers.
+         * Calling it when {@code isDrop()} is {@code false} results
+         * in an {@code IllegalStateException}.
+         *
+         * @return the action chosen for the drop
+         * @throws IllegalStateException if this is not a drop
+         * @see #setDropAction
+         * @see #getUserDropAction
+         * @see #isDrop()
+         */
+        public int getDropAction() {
+            return dropAction == -1 ? getUserDropAction() : dropAction;
+        }
+
+        /**
+         * Returns the user drop action for the drop, when this
+         * {@code TransferSupport} represents a drop.
+         * <p>
+         * The user drop action is chosen for a drop as described in the
+         * documentation for {@link java.awt.dnd.DropTargetDragEvent} and
+         * {@link java.awt.dnd.DropTargetDropEvent}. A different action
+         * may be chosen as the drop action by way of the {@code setDropAction}
+         * method.
+         * <p>
+         * You may wish to query this in {@code TransferHandler}'s
+         * {@code canImport} method when determining the suitability of a
+         * drop or when deciding on a drop action to explicitly choose.
+         * <p>
+         * This method is only for use with drag and drop transfers.
+         * Calling it when {@code isDrop()} is {@code false} results
+         * in an {@code IllegalStateException}.
+         *
+         * @return the user drop action
+         * @throws IllegalStateException if this is not a drop
+         * @see #setDropAction
+         * @see #getDropAction
+         * @see #isDrop()
+         */
+        public int getUserDropAction() {
+            assureIsDrop();
+
+            return (source instanceof DropTargetDragEvent)
+                ? ((DropTargetDragEvent)source).getDropAction()
+                : ((DropTargetDropEvent)source).getDropAction();
+        }
+
+        /**
+         * Returns the drag source's supported drop actions, when this
+         * {@code TransferSupport} represents a drop.
+         * <p>
+         * The source actions represent the set of actions supported by the
+         * source of this transfer, and are represented as some bitwise-OR
+         * combination of {@code COPY}, {@code MOVE} and {@code LINK}.
+         * You may wish to query this in {@code TransferHandler}'s
+         * {@code canImport} method when determining the suitability of a drop
+         * or when deciding on a drop action to explicitly choose. To determine
+         * if a particular action is supported by the source, bitwise-AND
+         * the action with the source drop actions, and then compare the result
+         * against the original action. For example:
+         * <pre>
+         * boolean copySupported = (COPY &amp; getSourceDropActions()) == COPY;
+         * </pre>
+         * <p>
+         * This method is only for use with drag and drop transfers.
+         * Calling it when {@code isDrop()} is {@code false} results
+         * in an {@code IllegalStateException}.
+         *
+         * @return the drag source's supported drop actions
+         * @throws IllegalStateException if this is not a drop
+         * @see #isDrop()
+         */
+        public int getSourceDropActions() {
+            assureIsDrop();
+
+            return (source instanceof DropTargetDragEvent)
+                ? ((DropTargetDragEvent)source).getSourceActions()
+                : ((DropTargetDropEvent)source).getSourceActions();
+        }
+
+        /**
+         * Returns the data flavors for this transfer.
+         *
+         * @return the data flavors for this transfer
+         */
+        public DataFlavor[] getDataFlavors() {
+            if (isDrop) {
+                if (source instanceof DropTargetDragEvent) {
+                    return ((DropTargetDragEvent)source).getCurrentDataFlavors();
+                } else {
+                    return ((DropTargetDropEvent)source).getCurrentDataFlavors();
+                }
+            }
+
+            return ((Transferable)source).getTransferDataFlavors();
+        }
+
+        /**
+         * Returns whether or not the given data flavor is supported.
+         *
+         * @param df the <code>DataFlavor</code> to test
+         * @return whether or not the given flavor is supported.
+         */
+        public boolean isDataFlavorSupported(DataFlavor df) {
+            if (isDrop) {
+                if (source instanceof DropTargetDragEvent) {
+                    return ((DropTargetDragEvent)source).isDataFlavorSupported(df);
+                } else {
+                    return ((DropTargetDropEvent)source).isDataFlavorSupported(df);
+                }
+            }
+
+            return ((Transferable)source).isDataFlavorSupported(df);
+        }
+
+        /**
+         * Returns the <code>Transferable</code> associated with this transfer.
+         * <p>
+         * Note: Unless it is necessary to fetch the <code>Transferable</code>
+         * directly, use one of the other methods on this class to inquire about
+         * the transfer. This may perform better than fetching the
+         * <code>Transferable</code> and asking it directly.
+         *
+         * @return the <code>Transferable</code> associated with this transfer
+         */
+        public Transferable getTransferable() {
+            if (isDrop) {
+                if (source instanceof DropTargetDragEvent) {
+                    return ((DropTargetDragEvent)source).getTransferable();
+                } else {
+                    return ((DropTargetDropEvent)source).getTransferable();
+                }
+            }
+
+            return (Transferable)source;
+        }
+    }
+
+
+    /**
+     * Returns an {@code Action} that performs cut operations to the
+     * clipboard. When performed, this action operates on the {@code JComponent}
+     * source of the {@code ActionEvent} by invoking {@code exportToClipboard},
+     * with a {@code MOVE} action, on the component's {@code TransferHandler}.
+     *
+     * @return an {@code Action} for performing cuts to the clipboard
+     */
+    public static Action getCutAction() {
+        return cutAction;
+    }
+
+    /**
+     * Returns an {@code Action} that performs copy operations to the
+     * clipboard. When performed, this action operates on the {@code JComponent}
+     * source of the {@code ActionEvent} by invoking {@code exportToClipboard},
+     * with a {@code COPY} action, on the component's {@code TransferHandler}.
+     *
+     * @return an {@code Action} for performing copies to the clipboard
+     */
+    public static Action getCopyAction() {
+        return copyAction;
+    }
+
+    /**
+     * Returns an {@code Action} that performs paste operations from the
+     * clipboard. When performed, this action operates on the {@code JComponent}
+     * source of the {@code ActionEvent} by invoking {@code importData},
+     * with the clipboard contents, on the component's {@code TransferHandler}.
+     *
+     * @return an {@code Action} for performing pastes from the clipboard
+     */
+    public static Action getPasteAction() {
+        return pasteAction;
+    }
+
+
+    /**
+     * Constructs a transfer handler that can transfer a Java Bean property
+     * from one component to another via the clipboard or a drag and drop
+     * operation.
+     *
+     * @param property  the name of the property to transfer; this can
+     *  be <code>null</code> if there is no property associated with the transfer
+     *  handler (a subclass that performs some other kind of transfer, for example)
+     */
+    public TransferHandler(String property) {
+        propertyName = property;
+    }
+
+    /**
+     * Convenience constructor for subclasses.
+     */
+    protected TransferHandler() {
+        this(null);
+    }
+
+
+    /**
+     * image for the {@code startDrag} method
+     *
+     * @see java.awt.dnd.DragGestureEvent#startDrag(Cursor dragCursor, Image dragImage, Point imageOffset, Transferable transferable, DragSourceListener dsl)
+     */
+    private  Image dragImage;
+
+    /**
+     * anchor offset for the {@code startDrag} method
+     *
+     * @see java.awt.dnd.DragGestureEvent#startDrag(Cursor dragCursor, Image dragImage, Point imageOffset, Transferable transferable, DragSourceListener dsl)
+     */
+    private  Point dragImageOffset;
+
+    /**
+     * Sets the drag image parameter. The image has to be prepared
+     * for rendering by the moment of the call. The image is stored
+     * by reference because of some performance reasons.
+     *
+     * @param img an image to drag
+     */
+    public void setDragImage(Image img) {
+        dragImage = img;
+    }
+
+    /**
+     * Returns the drag image. If there is no image to drag,
+     * the returned value is {@code null}.
+     *
+     * @return the reference to the drag image
+     */
+    public Image getDragImage() {
+        return dragImage;
+    }
+
+    /**
+     * Sets an anchor offset for the image to drag.
+     * It can not be {@code null}.
+     *
+     * @param p a {@code Point} object that corresponds
+     * to coordinates of an anchor offset of the image
+     * relative to the upper left corner of the image
+     */
+    public void setDragImageOffset(Point p) {
+        dragImageOffset = new Point(p);
+    }
+
+    /**
+     * Returns an anchor offset for the image to drag.
+     *
+     * @return a {@code Point} object that corresponds
+     * to coordinates of an anchor offset of the image
+     * relative to the upper left corner of the image.
+     * The point {@code (0,0)} returns by default.
+     */
+    public Point getDragImageOffset() {
+        if (dragImageOffset == null) {
+            return new Point(0,0);
+        }
+        return new Point(dragImageOffset);
+    }
+
+    /**
+     * Causes the Swing drag support to be initiated.  This is called by
+     * the various UI implementations in the <code>javax.swing.plaf.basic</code>
+     * package if the dragEnabled property is set on the component.
+     * This can be called by custom UI
+     * implementations to use the Swing drag support.  This method can also be called
+     * by a Swing extension written as a subclass of <code>JComponent</code>
+     * to take advantage of the Swing drag support.
+     * <p>
+     * The transfer <em>will not necessarily</em> have been completed at the
+     * return of this call (i.e. the call does not block waiting for the drop).
+     * The transfer will take place through the Swing implementation of the
+     * <code>java.awt.dnd</code> mechanism, requiring no further effort
+     * from the developer. The <code>exportDone</code> method will be called
+     * when the transfer has completed.
+     *
+     * @param comp  the component holding the data to be transferred;
+     *              provided to enable sharing of <code>TransferHandler</code>s
+     * @param e     the event that triggered the transfer
+     * @param action the transfer action initially requested;
+     *               either {@code COPY}, {@code MOVE} or {@code LINK};
+     *               the DnD system may change the action used during the
+     *               course of the drag operation
+     */
+    public void exportAsDrag(JComponent comp, InputEvent e, int action) {
+        int srcActions = getSourceActions(comp);
+
+        // only mouse events supported for drag operations
+        if (!(e instanceof MouseEvent)
+                // only support known actions
+                || !(action == COPY || action == MOVE || action == LINK)
+                // only support valid source actions
+                || (srcActions & action) == 0) {
+
+            action = NONE;
+        }
+
+        if (action != NONE && !GraphicsEnvironment.isHeadless()) {
+            if (recognizer == null) {
+                recognizer = new SwingDragGestureRecognizer(new DragHandler());
+            }
+            recognizer.gestured(comp, (MouseEvent)e, srcActions, action);
+        } else {
+            exportDone(comp, null, NONE);
+        }
+    }
+
+    /**
+     * Causes a transfer from the given component to the
+     * given clipboard.  This method is called by the default cut and
+     * copy actions registered in a component's action map.
+     * <p>
+     * The transfer will take place using the <code>java.awt.datatransfer</code>
+     * mechanism, requiring no further effort from the developer. Any data
+     * transfer <em>will</em> be complete and the <code>exportDone</code>
+     * method will be called with the action that occurred, before this method
+     * returns. Should the clipboard be unavailable when attempting to place
+     * data on it, the <code>IllegalStateException</code> thrown by
+     * {@link Clipboard#setContents(Transferable, ClipboardOwner)} will
+     * be propagated through this method. However,
+     * <code>exportDone</code> will first be called with an action
+     * of <code>NONE</code> for consistency.
+     *
+     * @param comp  the component holding the data to be transferred;
+     *              provided to enable sharing of <code>TransferHandler</code>s
+     * @param clip  the clipboard to transfer the data into
+     * @param action the transfer action requested; this should
+     *  be a value of either <code>COPY</code> or <code>MOVE</code>;
+     *  the operation performed is the intersection  of the transfer
+     *  capabilities given by getSourceActions and the requested action;
+     *  the intersection may result in an action of <code>NONE</code>
+     *  if the requested action isn't supported
+     * @throws IllegalStateException if the clipboard is currently unavailable
+     * @see Clipboard#setContents(Transferable, ClipboardOwner)
+     */
+    public void exportToClipboard(JComponent comp, Clipboard clip, int action)
+                                                  throws IllegalStateException {
+
+        if ((action == COPY || action == MOVE)
+                && (getSourceActions(comp) & action) != 0) {
+
+            Transferable t = createTransferable(comp);
+            if (t != null) {
+                try {
+                    clip.setContents(t, null);
+                    exportDone(comp, t, action);
+                    return;
+                } catch (IllegalStateException ise) {
+                    exportDone(comp, t, NONE);
+                    throw ise;
+                }
+            }
+        }
+
+        exportDone(comp, null, NONE);
+    }
+
+    /**
+     * Causes a transfer to occur from a clipboard or a drag and
+     * drop operation. The <code>Transferable</code> to be
+     * imported and the component to transfer to are contained
+     * within the <code>TransferSupport</code>.
+     * <p>
+     * While the drag and drop implementation calls {@code canImport}
+     * to determine the suitability of a transfer before calling this
+     * method, the implementation of paste does not. As such, it cannot
+     * be assumed that the transfer is acceptable upon a call to
+     * this method for paste. It is recommended that {@code canImport} be
+     * explicitly called to cover this case.
+     * <p>
+     * Note: The <code>TransferSupport</code> object passed to this method
+     * is only valid for the duration of the method call. It is undefined
+     * what values it may contain after this method returns.
+     *
+     * @param support the object containing the details of
+     *        the transfer, not <code>null</code>.
+     * @return true if the data was inserted into the component,
+     *         false otherwise
+     * @throws NullPointerException if <code>support</code> is {@code null}
+     * @see #canImport(TransferHandler.TransferSupport)
+     * @since 1.6
+     */
+    public boolean importData(TransferSupport support) {
+        return support.getComponent() instanceof JComponent
+            ? importData((JComponent)support.getComponent(), support.getTransferable())
+            : false;
+    }
+
+    /**
+     * Causes a transfer to a component from a clipboard or a
+     * DND drop operation.  The <code>Transferable</code> represents
+     * the data to be imported into the component.
+     * <p>
+     * Note: Swing now calls the newer version of <code>importData</code>
+     * that takes a <code>TransferSupport</code>, which in turn calls this
+     * method (if the component in the {@code TransferSupport} is a
+     * {@code JComponent}). Developers are encouraged to call and override the
+     * newer version as it provides more information (and is the only
+     * version that supports use with a {@code TransferHandler} set directly
+     * on a {@code JFrame} or other non-{@code JComponent}).
+     *
+     * @param comp  the component to receive the transfer;
+     *              provided to enable sharing of <code>TransferHandler</code>s
+     * @param t     the data to import
+     * @return  true if the data was inserted into the component, false otherwise
+     * @see #importData(TransferHandler.TransferSupport)
+     */
+    public boolean importData(JComponent comp, Transferable t) {
+        PropertyDescriptor prop = getPropertyDescriptor(comp);
+        if (prop != null) {
+            Method writer = prop.getWriteMethod();
+            if (writer == null) {
+                // read-only property. ignore
+                return false;
+            }
+            Class<?>[] params = writer.getParameterTypes();
+            if (params.length != 1) {
+                // zero or more than one argument, ignore
+                return false;
+            }
+            DataFlavor flavor = getPropertyDataFlavor(params[0], t.getTransferDataFlavors());
+            if (flavor != null) {
+                try {
+                    Object value = t.getTransferData(flavor);
+                    Object[] args = { value };
+                    MethodUtil.invoke(writer, comp, args);
+                    return true;
+                } catch (Exception ex) {
+                    System.err.println("Invocation failed");
+                    // invocation code
+                }
+            }
+        }
+        return false;
+    }
+
+    /**
+     * This method is called repeatedly during a drag and drop operation
+     * to allow the developer to configure properties of, and to return
+     * the acceptability of transfers; with a return value of {@code true}
+     * indicating that the transfer represented by the given
+     * {@code TransferSupport} (which contains all of the details of the
+     * transfer) is acceptable at the current time, and a value of {@code false}
+     * rejecting the transfer.
+     * <p>
+     * For those components that automatically display a drop location during
+     * drag and drop, accepting the transfer, by default, tells them to show
+     * the drop location. This can be changed by calling
+     * {@code setShowDropLocation} on the {@code TransferSupport}.
+     * <p>
+     * By default, when the transfer is accepted, the chosen drop action is that
+     * picked by the user via their drag gesture. The developer can override
+     * this and choose a different action, from the supported source
+     * actions, by calling {@code setDropAction} on the {@code TransferSupport}.
+     * <p>
+     * On every call to {@code canImport}, the {@code TransferSupport} contains
+     * fresh state. As such, any properties set on it must be set on every
+     * call. Upon a drop, {@code canImport} is called one final time before
+     * calling into {@code importData}. Any state set on the
+     * {@code TransferSupport} during that last call will be available in
+     * {@code importData}.
+     * <p>
+     * This method is not called internally in response to paste operations.
+     * As such, it is recommended that implementations of {@code importData}
+     * explicitly call this method for such cases and that this method
+     * be prepared to return the suitability of paste operations as well.
+     * <p>
+     * Note: The <code>TransferSupport</code> object passed to this method
+     * is only valid for the duration of the method call. It is undefined
+     * what values it may contain after this method returns.
+     *
+     * @param support the object containing the details of
+     *        the transfer, not <code>null</code>.
+     * @return <code>true</code> if the import can happen,
+     *         <code>false</code> otherwise
+     * @throws NullPointerException if <code>support</code> is {@code null}
+     * @see #importData(TransferHandler.TransferSupport)
+     * @see javax.swing.TransferHandler.TransferSupport#setShowDropLocation
+     * @see javax.swing.TransferHandler.TransferSupport#setDropAction
+     * @since 1.6
+     */
+    public boolean canImport(TransferSupport support) {
+        return support.getComponent() instanceof JComponent
+            ? canImport((JComponent)support.getComponent(), support.getDataFlavors())
+            : false;
+    }
+
+    /**
+     * Indicates whether a component will accept an import of the given
+     * set of data flavors prior to actually attempting to import it.
+     * <p>
+     * Note: Swing now calls the newer version of <code>canImport</code>
+     * that takes a <code>TransferSupport</code>, which in turn calls this
+     * method (only if the component in the {@code TransferSupport} is a
+     * {@code JComponent}). Developers are encouraged to call and override the
+     * newer version as it provides more information (and is the only
+     * version that supports use with a {@code TransferHandler} set directly
+     * on a {@code JFrame} or other non-{@code JComponent}).
+     *
+     * @param comp  the component to receive the transfer;
+     *              provided to enable sharing of <code>TransferHandler</code>s
+     * @param transferFlavors  the data formats available
+     * @return  true if the data can be inserted into the component, false otherwise
+     * @see #canImport(TransferHandler.TransferSupport)
+     */
+    public boolean canImport(JComponent comp, DataFlavor[] transferFlavors) {
+        PropertyDescriptor prop = getPropertyDescriptor(comp);
+        if (prop != null) {
+            Method writer = prop.getWriteMethod();
+            if (writer == null) {
+                // read-only property. ignore
+                return false;
+            }
+            Class<?>[] params = writer.getParameterTypes();
+            if (params.length != 1) {
+                // zero or more than one argument, ignore
+                return false;
+            }
+            DataFlavor flavor = getPropertyDataFlavor(params[0], transferFlavors);
+            if (flavor != null) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Returns the type of transfer actions supported by the source;
+     * any bitwise-OR combination of {@code COPY}, {@code MOVE}
+     * and {@code LINK}.
+     * <p>
+     * Some models are not mutable, so a transfer operation of {@code MOVE}
+     * should not be advertised in that case. Returning {@code NONE}
+     * disables transfers from the component.
+     *
+     * @param c  the component holding the data to be transferred;
+     *           provided to enable sharing of <code>TransferHandler</code>s
+     * @return {@code COPY} if the transfer property can be found,
+     *          otherwise returns <code>NONE</code>
+     */
+    public int getSourceActions(JComponent c) {
+        PropertyDescriptor prop = getPropertyDescriptor(c);
+        if (prop != null) {
+            return COPY;
+        }
+        return NONE;
+    }
+
+    /**
+     * Returns an object that establishes the look of a transfer.  This is
+     * useful for both providing feedback while performing a drag operation and for
+     * representing the transfer in a clipboard implementation that has a visual
+     * appearance.  The implementation of the <code>Icon</code> interface should
+     * not alter the graphics clip or alpha level.
+     * The icon implementation need not be rectangular or paint all of the
+     * bounding rectangle and logic that calls the icons paint method should
+     * not assume the all bits are painted. <code>null</code> is a valid return value
+     * for this method and indicates there is no visual representation provided.
+     * In that case, the calling logic is free to represent the
+     * transferable however it wants.
+     * <p>
+     * The default Swing logic will not do an alpha blended drag animation if
+     * the return is <code>null</code>.
+     *
+     * @param t  the data to be transferred; this value is expected to have been
+     *  created by the <code>createTransferable</code> method
+     * @return  <code>null</code>, indicating
+     *    there is no default visual representation
+     */
+    public Icon getVisualRepresentation(Transferable t) {
+        return null;
+    }
+
+    /**
+     * Creates a <code>Transferable</code> to use as the source for
+     * a data transfer. Returns the representation of the data to
+     * be transferred, or <code>null</code> if the component's
+     * property is <code>null</code>
+     *
+     * @param c  the component holding the data to be transferred;
+     *              provided to enable sharing of <code>TransferHandler</code>s
+     * @return  the representation of the data to be transferred, or
+     *  <code>null</code> if the property associated with <code>c</code>
+     *  is <code>null</code>
+     *
+     */
+    protected Transferable createTransferable(JComponent c) {
+        PropertyDescriptor property = getPropertyDescriptor(c);
+        if (property != null) {
+            return new PropertyTransferable(property, c);
+        }
+        return null;
+    }
+
+    /**
+     * Invoked after data has been exported.  This method should remove
+     * the data that was transferred if the action was <code>MOVE</code>.
+     * <p>
+     * This method is implemented to do nothing since <code>MOVE</code>
+     * is not a supported action of this implementation
+     * (<code>getSourceActions</code> does not include <code>MOVE</code>).
+     *
+     * @param source the component that was the source of the data
+     * @param data   The data that was transferred or possibly null
+     *               if the action is <code>NONE</code>.
+     * @param action the actual action that was performed
+     */
+    protected void exportDone(JComponent source, Transferable data, int action) {
+    }
+
+    /**
+     * Fetches the property descriptor for the property assigned to this transfer
+     * handler on the given component (transfer handler may be shared).  This
+     * returns <code>null</code> if the property descriptor can't be found
+     * or there is an error attempting to fetch the property descriptor.
+     */
+    private PropertyDescriptor getPropertyDescriptor(JComponent comp) {
+        if (propertyName == null) {
+            return null;
+        }
+        Class<?> k = comp.getClass();
+        BeanInfo bi;
+        try {
+            bi = Introspector.getBeanInfo(k);
+        } catch (IntrospectionException ex) {
+            return null;
+        }
+        PropertyDescriptor props[] = bi.getPropertyDescriptors();
+        for (int i=0; i < props.length; i++) {
+            if (propertyName.equals(props[i].getName())) {
+                Method reader = props[i].getReadMethod();
+
+                if (reader != null) {
+                    Class<?>[] params = reader.getParameterTypes();
+
+                    if (params == null || params.length == 0) {
+                        // found the desired descriptor
+                        return props[i];
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Fetches the data flavor from the array of possible flavors that
+     * has data of the type represented by property type.  Null is
+     * returned if there is no match.
+     */
+    private DataFlavor getPropertyDataFlavor(Class<?> k, DataFlavor[] flavors) {
+        for(int i = 0; i < flavors.length; i++) {
+            DataFlavor flavor = flavors[i];
+            if ("application".equals(flavor.getPrimaryType()) &&
+                "x-java-jvm-local-objectref".equals(flavor.getSubType()) &&
+                k.isAssignableFrom(flavor.getRepresentationClass())) {
+
+                return flavor;
+            }
+        }
+        return null;
+    }
+
+
+    private String propertyName;
+    private static SwingDragGestureRecognizer recognizer = null;
+
+    private static DropTargetListener getDropTargetListener() {
+        synchronized(DropHandler.class) {
+            DropHandler handler =
+                (DropHandler)AppContext.getAppContext().get(DropHandler.class);
+
+            if (handler == null) {
+                handler = new DropHandler();
+                AppContext.getAppContext().put(DropHandler.class, handler);
+            }
+
+            return handler;
+        }
+    }
+
+    static class PropertyTransferable implements Transferable {
+
+        PropertyTransferable(PropertyDescriptor p, JComponent c) {
+            property = p;
+            component = c;
+        }
+
+        // --- Transferable methods ----------------------------------------------
+
+        /**
+         * Returns an array of <code>DataFlavor</code> objects indicating the flavors the data
+         * can be provided in.  The array should be ordered according to preference
+         * for providing the data (from most richly descriptive to least descriptive).
+         * @return an array of data flavors in which this data can be transferred
+         */
+        public DataFlavor[] getTransferDataFlavors() {
+            DataFlavor[] flavors = new DataFlavor[1];
+            Class<?> propertyType = property.getPropertyType();
+            String mimeType = DataFlavor.javaJVMLocalObjectMimeType + ";class=" + propertyType.getName();
+            try {
+                flavors[0] = new DataFlavor(mimeType);
+            } catch (ClassNotFoundException cnfe) {
+                flavors = new DataFlavor[0];
+            }
+            return flavors;
+        }
+
+        /**
+         * Returns whether the specified data flavor is supported for
+         * this object.
+         * @param flavor the requested flavor for the data
+         * @return true if this <code>DataFlavor</code> is supported,
+         *   otherwise false
+         */
+        public boolean isDataFlavorSupported(DataFlavor flavor) {
+            Class<?> propertyType = property.getPropertyType();
+            if ("application".equals(flavor.getPrimaryType()) &&
+                "x-java-jvm-local-objectref".equals(flavor.getSubType()) &&
+                flavor.getRepresentationClass().isAssignableFrom(propertyType)) {
+
+                return true;
+            }
+            return false;
+        }
+
+        /**
+         * Returns an object which represents the data to be transferred.  The class
+         * of the object returned is defined by the representation class of the flavor.
+         *
+         * @param flavor the requested flavor for the data
+         * @see DataFlavor#getRepresentationClass
+         * @exception IOException                if the data is no longer available
+         *              in the requested flavor.
+         * @exception UnsupportedFlavorException if the requested data flavor is
+         *              not supported.
+         */
+        public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException {
+            if (! isDataFlavorSupported(flavor)) {
+                throw new UnsupportedFlavorException(flavor);
+            }
+            Method reader = property.getReadMethod();
+            Object value = null;
+            try {
+                value = MethodUtil.invoke(reader, component, (Object[])null);
+            } catch (Exception ex) {
+                throw new IOException("Property read failed: " + property.getName());
+            }
+            return value;
+        }
+
+        JComponent component;
+        PropertyDescriptor property;
+    }
+
+    /**
+     * This is the default drop target for drag and drop operations if
+     * one isn't provided by the developer.  <code>DropTarget</code>
+     * only supports one <code>DropTargetListener</code> and doesn't
+     * function properly if it isn't set.
+     * This class sets the one listener as the linkage of drop handling
+     * to the <code>TransferHandler</code>, and adds support for
+     * additional listeners which some of the <code>ComponentUI</code>
+     * implementations install to manipulate a drop insertion location.
+     */
+    static class SwingDropTarget extends DropTarget implements UIResource {
+
+        SwingDropTarget(Component c) {
+            super(c, COPY_OR_MOVE | LINK, null);
+            try {
+                // addDropTargetListener is overridden
+                // we specifically need to add to the superclass
+                super.addDropTargetListener(getDropTargetListener());
+            } catch (TooManyListenersException tmle) {}
+        }
+
+        public void addDropTargetListener(DropTargetListener dtl) throws TooManyListenersException {
+            // Since the super class only supports one DropTargetListener,
+            // and we add one from the constructor, we always add to the
+            // extended list.
+            if (listenerList == null) {
+                listenerList = new EventListenerList();
+            }
+            listenerList.add(DropTargetListener.class, dtl);
+        }
+
+        public void removeDropTargetListener(DropTargetListener dtl) {
+            if (listenerList != null) {
+                listenerList.remove(DropTargetListener.class, dtl);
+            }
+        }
+
+        // --- DropTargetListener methods (multicast) --------------------------
+
+        public void dragEnter(DropTargetDragEvent e) {
+            super.dragEnter(e);
+            if (listenerList != null) {
+                Object[] listeners = listenerList.getListenerList();
+                for (int i = listeners.length-2; i>=0; i-=2) {
+                    if (listeners[i]==DropTargetListener.class) {
+                        ((DropTargetListener)listeners[i+1]).dragEnter(e);
+                    }
+                }
+            }
+        }
+
+        public void dragOver(DropTargetDragEvent e) {
+            super.dragOver(e);
+            if (listenerList != null) {
+                Object[] listeners = listenerList.getListenerList();
+                for (int i = listeners.length-2; i>=0; i-=2) {
+                    if (listeners[i]==DropTargetListener.class) {
+                        ((DropTargetListener)listeners[i+1]).dragOver(e);
+                    }
+                }
+            }
+        }
+
+        public void dragExit(DropTargetEvent e) {
+            super.dragExit(e);
+            if (listenerList != null) {
+                Object[] listeners = listenerList.getListenerList();
+                for (int i = listeners.length-2; i>=0; i-=2) {
+                    if (listeners[i]==DropTargetListener.class) {
+                        ((DropTargetListener)listeners[i+1]).dragExit(e);
+                    }
+                }
+            }
+            if (!isActive()) {
+                // If the Drop target is inactive the dragExit will not be dispatched to the dtListener,
+                // so make sure that we clean up the dtListener anyway.
+                DropTargetListener dtListener = getDropTargetListener();
+                    if (dtListener != null && dtListener instanceof DropHandler) {
+                        ((DropHandler)dtListener).cleanup(false);
+                    }
+            }
+        }
+
+        public void drop(DropTargetDropEvent e) {
+            super.drop(e);
+            if (listenerList != null) {
+                Object[] listeners = listenerList.getListenerList();
+                for (int i = listeners.length-2; i>=0; i-=2) {
+                    if (listeners[i]==DropTargetListener.class) {
+                        ((DropTargetListener)listeners[i+1]).drop(e);
+                    }
+                }
+            }
+        }
+
+        public void dropActionChanged(DropTargetDragEvent e) {
+            super.dropActionChanged(e);
+            if (listenerList != null) {
+                Object[] listeners = listenerList.getListenerList();
+                for (int i = listeners.length-2; i>=0; i-=2) {
+                    if (listeners[i]==DropTargetListener.class) {
+                        ((DropTargetListener)listeners[i+1]).dropActionChanged(e);
+                    }
+                }
+            }
+        }
+
+        private EventListenerList listenerList;
+    }
+
+    private static class DropHandler implements DropTargetListener,
+                                                Serializable,
+                                                ActionListener {
+
+        private Timer timer;
+        private Point lastPosition;
+        private Rectangle outer = new Rectangle();
+        private Rectangle inner = new Rectangle();
+        private int hysteresis = 10;
+
+        private Component component;
+        private Object state;
+        private TransferSupport support =
+            new TransferSupport(null, (DropTargetEvent)null);
+
+        private static final int AUTOSCROLL_INSET = 10;
+
+        /**
+         * Update the geometry of the autoscroll region.  The geometry is
+         * maintained as a pair of rectangles.  The region can cause
+         * a scroll if the pointer sits inside it for the duration of the
+         * timer.  The region that causes the timer countdown is the area
+         * between the two rectangles.
+         * <p>
+         * This is implemented to use the visible area of the component
+         * as the outer rectangle, and the insets are fixed at 10. Should
+         * the component be smaller than a total of 20 in any direction,
+         * autoscroll will not occur in that direction.
+         */
+        private void updateAutoscrollRegion(JComponent c) {
+            // compute the outer
+            Rectangle visible = c.getVisibleRect();
+            outer.setBounds(visible.x, visible.y, visible.width, visible.height);
+
+            // compute the insets
+            Insets i = new Insets(0, 0, 0, 0);
+            if (c instanceof Scrollable) {
+                int minSize = 2 * AUTOSCROLL_INSET;
+
+                if (visible.width >= minSize) {
+                    i.left = i.right = AUTOSCROLL_INSET;
+                }
+
+                if (visible.height >= minSize) {
+                    i.top = i.bottom = AUTOSCROLL_INSET;
+                }
+            }
+
+            // set the inner from the insets
+            inner.setBounds(visible.x + i.left,
+                          visible.y + i.top,
+                          visible.width - (i.left + i.right),
+                          visible.height - (i.top  + i.bottom));
+        }
+
+        /**
+         * Perform an autoscroll operation.  This is implemented to scroll by the
+         * unit increment of the Scrollable using scrollRectToVisible.  If the
+         * cursor is in a corner of the autoscroll region, more than one axis will
+         * scroll.
+         */
+        private void autoscroll(JComponent c, Point pos) {
+            if (c instanceof Scrollable) {
+                Scrollable s = (Scrollable) c;
+                if (pos.y < inner.y) {
+                    // scroll upward
+                    int dy = s.getScrollableUnitIncrement(outer, SwingConstants.VERTICAL, -1);
+                    Rectangle r = new Rectangle(inner.x, outer.y - dy, inner.width, dy);
+                    c.scrollRectToVisible(r);
+                } else if (pos.y > (inner.y + inner.height)) {
+                    // scroll downard
+                    int dy = s.getScrollableUnitIncrement(outer, SwingConstants.VERTICAL, 1);
+                    Rectangle r = new Rectangle(inner.x, outer.y + outer.height, inner.width, dy);
+                    c.scrollRectToVisible(r);
+                }
+
+                if (pos.x < inner.x) {
+                    // scroll left
+                    int dx = s.getScrollableUnitIncrement(outer, SwingConstants.HORIZONTAL, -1);
+                    Rectangle r = new Rectangle(outer.x - dx, inner.y, dx, inner.height);
+                    c.scrollRectToVisible(r);
+                } else if (pos.x > (inner.x + inner.width)) {
+                    // scroll right
+                    int dx = s.getScrollableUnitIncrement(outer, SwingConstants.HORIZONTAL, 1);
+                    Rectangle r = new Rectangle(outer.x + outer.width, inner.y, dx, inner.height);
+                    c.scrollRectToVisible(r);
+                }
+            }
+        }
+
+        /**
+         * Initializes the internal properties if they haven't been already
+         * inited. This is done lazily to avoid loading of desktop properties.
+         */
+        private void initPropertiesIfNecessary() {
+            if (timer == null) {
+                Toolkit t = Toolkit.getDefaultToolkit();
+                Integer prop;
+
+                prop = (Integer)
+                    t.getDesktopProperty("DnD.Autoscroll.interval");
+
+                timer = new Timer(prop == null ? 100 : prop.intValue(), this);
+
+                prop = (Integer)
+                    t.getDesktopProperty("DnD.Autoscroll.initialDelay");
+
+                timer.setInitialDelay(prop == null ? 100 : prop.intValue());
+
+                prop = (Integer)
+                    t.getDesktopProperty("DnD.Autoscroll.cursorHysteresis");
+
+                if (prop != null) {
+                    hysteresis = prop.intValue();
+                }
+            }
+        }
+
+        /**
+         * The timer fired, perform autoscroll if the pointer is within the
+         * autoscroll region.
+         * <P>
+         * @param e the <code>ActionEvent</code>
+         */
+        public void actionPerformed(ActionEvent e) {
+            updateAutoscrollRegion((JComponent)component);
+            if (outer.contains(lastPosition) && !inner.contains(lastPosition)) {
+                autoscroll((JComponent)component, lastPosition);
+            }
+        }
+
+        // --- DropTargetListener methods -----------------------------------
+
+        private void setComponentDropLocation(TransferSupport support,
+                                              boolean forDrop) {
+
+            DropLocation dropLocation = (support == null)
+                                        ? null
+                                        : support.getDropLocation();
+
+            if (SunToolkit.isInstanceOf(component, "javax.swing.text.JTextComponent")) {
+                state = SwingAccessor.getJTextComponentAccessor().
+                            setDropLocation((JTextComponent)component, dropLocation, state, forDrop);
+            } else if (component instanceof JComponent) {
+                state = ((JComponent)component).setDropLocation(dropLocation, state, forDrop);
+            }
+        }
+
+        private void handleDrag(DropTargetDragEvent e) {
+            TransferHandler importer =
+                ((HasGetTransferHandler)component).getTransferHandler();
+
+            if (importer == null) {
+                e.rejectDrag();
+                setComponentDropLocation(null, false);
+                return;
+            }
+
+            support.setDNDVariables(component, e);
+            boolean canImport = importer.canImport(support);
+
+            if (canImport) {
+                e.acceptDrag(support.getDropAction());
+            } else {
+                e.rejectDrag();
+            }
+
+            boolean showLocation = support.showDropLocationIsSet ?
+                                   support.showDropLocation :
+                                   canImport;
+
+            setComponentDropLocation(showLocation ? support : null, false);
+        }
+
+        public void dragEnter(DropTargetDragEvent e) {
+            state = null;
+            component = e.getDropTargetContext().getComponent();
+
+            handleDrag(e);
+
+            if (component instanceof JComponent) {
+                lastPosition = e.getLocation();
+                updateAutoscrollRegion((JComponent)component);
+                initPropertiesIfNecessary();
+            }
+        }
+
+        public void dragOver(DropTargetDragEvent e) {
+            handleDrag(e);
+
+            if (!(component instanceof JComponent)) {
+                return;
+            }
+
+            Point p = e.getLocation();
+
+            if (Math.abs(p.x - lastPosition.x) > hysteresis
+                    || Math.abs(p.y - lastPosition.y) > hysteresis) {
+                // no autoscroll
+                if (timer.isRunning()) timer.stop();
+            } else {
+                if (!timer.isRunning()) timer.start();
+            }
+
+            lastPosition = p;
+        }
+
+        public void dragExit(DropTargetEvent e) {
+            cleanup(false);
+        }
+
+        public void drop(DropTargetDropEvent e) {
+            TransferHandler importer =
+                ((HasGetTransferHandler)component).getTransferHandler();
+
+            if (importer == null) {
+                e.rejectDrop();
+                cleanup(false);
+                return;
+            }
+
+            support.setDNDVariables(component, e);
+            boolean canImport = importer.canImport(support);
+
+            if (canImport) {
+                e.acceptDrop(support.getDropAction());
+
+                boolean showLocation = support.showDropLocationIsSet ?
+                                       support.showDropLocation :
+                                       canImport;
+
+                setComponentDropLocation(showLocation ? support : null, false);
+
+                boolean success;
+
+                try {
+                    success = importer.importData(support);
+                } catch (RuntimeException re) {
+                    success = false;
+                }
+
+                e.dropComplete(success);
+                cleanup(success);
+            } else {
+                e.rejectDrop();
+                cleanup(false);
+            }
+        }
+
+        public void dropActionChanged(DropTargetDragEvent e) {
+            /*
+             * Work-around for Linux bug where dropActionChanged
+             * is called before dragEnter.
+             */
+            if (component == null) {
+                return;
+            }
+
+            handleDrag(e);
+        }
+
+        private void cleanup(boolean forDrop) {
+            setComponentDropLocation(null, forDrop);
+            if (component instanceof JComponent) {
+                ((JComponent)component).dndDone();
+            }
+
+            if (timer != null) {
+                timer.stop();
+            }
+
+            state = null;
+            component = null;
+            lastPosition = null;
+        }
+    }
+
+    /**
+     * This is the default drag handler for drag and drop operations that
+     * use the <code>TransferHandler</code>.
+     */
+    private static class DragHandler implements DragGestureListener, DragSourceListener {
+
+        private boolean scrolls;
+
+        // --- DragGestureListener methods -----------------------------------
+
+        /**
+         * a Drag gesture has been recognized
+         */
+        public void dragGestureRecognized(DragGestureEvent dge) {
+            JComponent c = (JComponent) dge.getComponent();
+            TransferHandler th = c.getTransferHandler();
+            Transferable t = th.createTransferable(c);
+            if (t != null) {
+                scrolls = c.getAutoscrolls();
+                c.setAutoscrolls(false);
+                try {
+                    Image im = th.getDragImage();
+                    if (im == null) {
+                        dge.startDrag(null, t, this);
+                    } else {
+                        dge.startDrag(null, im, th.getDragImageOffset(), t, this);
+                    }
+                    return;
+                } catch (RuntimeException re) {
+                    c.setAutoscrolls(scrolls);
+                }
+            }
+
+            th.exportDone(c, t, NONE);
+        }
+
+        // --- DragSourceListener methods -----------------------------------
+
+        /**
+         * as the hotspot enters a platform dependent drop site
+         */
+        public void dragEnter(DragSourceDragEvent dsde) {
+        }
+
+        /**
+         * as the hotspot moves over a platform dependent drop site
+         */
+        public void dragOver(DragSourceDragEvent dsde) {
+        }
+
+        /**
+         * as the hotspot exits a platform dependent drop site
+         */
+        public void dragExit(DragSourceEvent dsde) {
+        }
+
+        /**
+         * as the operation completes
+         */
+        public void dragDropEnd(DragSourceDropEvent dsde) {
+            DragSourceContext dsc = dsde.getDragSourceContext();
+            JComponent c = (JComponent)dsc.getComponent();
+            if (dsde.getDropSuccess()) {
+                c.getTransferHandler().exportDone(c, dsc.getTransferable(), dsde.getDropAction());
+            } else {
+                c.getTransferHandler().exportDone(c, dsc.getTransferable(), NONE);
+            }
+            c.setAutoscrolls(scrolls);
+        }
+
+        public void dropActionChanged(DragSourceDragEvent dsde) {
+        }
+    }
+
+    private static class SwingDragGestureRecognizer extends DragGestureRecognizer {
+
+        SwingDragGestureRecognizer(DragGestureListener dgl) {
+            super(DragSource.getDefaultDragSource(), null, NONE, dgl);
+        }
+
+        void gestured(JComponent c, MouseEvent e, int srcActions, int action) {
+            setComponent(c);
+            setSourceActions(srcActions);
+            appendEvent(e);
+            fireDragGestureRecognized(action, e.getPoint());
+        }
+
+        /**
+         * register this DragGestureRecognizer's Listeners with the Component
+         */
+        protected void registerListeners() {
+        }
+
+        /**
+         * unregister this DragGestureRecognizer's Listeners with the Component
+         *
+         * subclasses must override this method
+         */
+        protected void unregisterListeners() {
+        }
+
+    }
+
+    static final Action cutAction = new TransferAction("cut");
+    static final Action copyAction = new TransferAction("copy");
+    static final Action pasteAction = new TransferAction("paste");
+
+    static class TransferAction extends UIAction implements UIResource {
+
+        TransferAction(String name) {
+            super(name);
+        }
+
+        public boolean isEnabled(Object sender) {
+            if (sender instanceof JComponent
+                && ((JComponent)sender).getTransferHandler() == null) {
+                    return false;
+            }
+
+            return true;
+        }
+
+        private static final JavaSecurityAccess javaSecurityAccess =
+            SharedSecrets.getJavaSecurityAccess();
+
+        public void actionPerformed(final ActionEvent e) {
+            final Object src = e.getSource();
+
+            final PrivilegedAction<Void> action = new PrivilegedAction<Void>() {
+                public Void run() {
+                    actionPerformedImpl(e);
+                    return null;
+                }
+            };
+
+            final AccessControlContext stack = AccessController.getContext();
+            final AccessControlContext srcAcc = AWTAccessor.getComponentAccessor().getAccessControlContext((Component)src);
+            final AccessControlContext eventAcc = AWTAccessor.getAWTEventAccessor().getAccessControlContext(e);
+
+                if (srcAcc == null) {
+                    javaSecurityAccess.doIntersectionPrivilege(action, stack, eventAcc);
+                } else {
+                    javaSecurityAccess.doIntersectionPrivilege(
+                        new PrivilegedAction<Void>() {
+                            public Void run() {
+                                javaSecurityAccess.doIntersectionPrivilege(action, eventAcc);
+                                return null;
+                             }
+                    }, stack, srcAcc);
+                }
+        }
+
+        private void actionPerformedImpl(ActionEvent e) {
+            Object src = e.getSource();
+            if (src instanceof JComponent) {
+                JComponent c = (JComponent) src;
+                TransferHandler th = c.getTransferHandler();
+                Clipboard clipboard = getClipboard(c);
+                String name = (String) getValue(Action.NAME);
+
+                Transferable trans = null;
+
+                // any of these calls may throw IllegalStateException
+                try {
+                    if ((clipboard != null) && (th != null) && (name != null)) {
+                        if ("cut".equals(name)) {
+                            th.exportToClipboard(c, clipboard, MOVE);
+                        } else if ("copy".equals(name)) {
+                            th.exportToClipboard(c, clipboard, COPY);
+                        } else if ("paste".equals(name)) {
+                            trans = clipboard.getContents(null);
+                        }
+                    }
+                } catch (IllegalStateException ise) {
+                    // clipboard was unavailable
+                    UIManager.getLookAndFeel().provideErrorFeedback(c);
+                    return;
+                }
+
+                // this is a paste action, import data into the component
+                if (trans != null) {
+                    th.importData(new TransferSupport(c, trans));
+                }
+            }
+        }
+
+        /**
+         * Returns the clipboard to use for cut/copy/paste.
+         */
+        private Clipboard getClipboard(JComponent c) {
+            if (SwingUtilities2.canAccessSystemClipboard()) {
+                return c.getToolkit().getSystemClipboard();
+            }
+            Clipboard clipboard = (Clipboard)sun.awt.AppContext.getAppContext().
+                get(SandboxClipboardKey);
+            if (clipboard == null) {
+                clipboard = new Clipboard("Sandboxed Component Clipboard");
+                sun.awt.AppContext.getAppContext().put(SandboxClipboardKey,
+                                                       clipboard);
+            }
+            return clipboard;
+        }
+
+        /**
+         * Key used in app context to lookup Clipboard to use if access to
+         * System clipboard is denied.
+         */
+        private static Object SandboxClipboardKey = new Object();
+
+    }
+
+}