/*

 * Copyright (c) 2000, 2009, 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

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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;

/**

 * 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://java.sun.com/docs/books/tutorial/uiswing/misc/dnd.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

     * "copy" or "move".

     */

    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

         */

        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

         */

        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

         */

        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

         */

        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

         */

        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 & 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

         */

        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();

                }

            }