/*

 * Copyright 1997-2006 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.awt.dnd;

import java.awt.event.InputEvent;

/**

 * The <code>DragSourceDragEvent</code> is

 * delivered from the <code>DragSourceContextPeer</code>,

 * via the <code>DragSourceContext</code>, to the <code>DragSourceListener</code>

 * registered with that <code>DragSourceContext</code> and with its associated

 * <code>DragSource</code>.

 * <p>

 * The <code>DragSourceDragEvent</code> reports the <i>target drop action</i>

 * and the <i>user drop action</i> that reflect the current state of

 * the drag operation.

 * <p>

 * <i>Target drop action</i> is one of <code>DnDConstants</code> that represents

 * the drop action selected by the current drop target if this drop action is

 * supported by the drag source or <code>DnDConstants.ACTION_NONE</code> if this

 * drop action is not supported by the drag source.

 * <p>

 * <i>User drop action</i> depends on the drop actions supported by the drag

 * source and the drop action selected by the user. The user can select a drop

 * action by pressing modifier keys during the drag operation:

 * <pre>

 *   Ctrl + Shift -> ACTION_LINK

 *   Ctrl         -> ACTION_COPY

 *   Shift        -> ACTION_MOVE

 * </pre>

 * If the user selects a drop action, the <i>user drop action</i> is one of

 * <code>DnDConstants</code> that represents the selected drop action if this

 * drop action is supported by the drag source or

 * <code>DnDConstants.ACTION_NONE</code> if this drop action is not supported

 * by the drag source.

 * <p>

 * If the user doesn't select a drop action, the set of

 * <code>DnDConstants</code> that represents the set of drop actions supported

 * by the drag source is searched for <code>DnDConstants.ACTION_MOVE</code>,

 * then for <code>DnDConstants.ACTION_COPY</code>, then for

 * <code>DnDConstants.ACTION_LINK</code> and the <i>user drop action</i> is the

 * first constant found. If no constant is found the <i>user drop action</i>

 * is <code>DnDConstants.ACTION_NONE</code>.

 *

 * @since 1.2

 *

 */

public class DragSourceDragEvent extends DragSourceEvent {

    private static final long serialVersionUID = 481346297933902471L;

    /**

     * Constructs a <code>DragSourceDragEvent</code>.

     * This class is typically

     * instantiated by the <code>DragSourceContextPeer</code>

     * rather than directly

     * by client code.

     * The coordinates for this <code>DragSourceDragEvent</code>

     * are not specified, so <code>getLocation</code> will return

     * <code>null</code> for this event.

     * <p>

     * The arguments <code>dropAction</code> and <code>action</code> should

     * be one of <code>DnDConstants</code> that represents a single action.

     * The argument <code>modifiers</code> should be either a bitwise mask

     * of old <code>java.awt.event.InputEvent.*_MASK</code> constants or a

     * bitwise mask of extended <code>java.awt.event.InputEvent.*_DOWN_MASK</code>

     * constants.

     * This constructor does not throw any exception for invalid <code>dropAction</code>,

     * <code>action</code> and <code>modifiers</code>.

     *

     * @param dsc the <code>DragSourceContext</code> that is to manage

     *            notifications for this event.

     * @param dropAction the user drop action.

     * @param action the target drop action.

     * @param modifiers the modifier keys down during event (shift, ctrl,

     *        alt, meta)

     *        Either extended _DOWN_MASK or old _MASK modifiers

     *        should be used, but both models should not be mixed

     *        in one event. Use of the extended modifiers is

     *        preferred.

     *

     * @throws <code>IllegalArgumentException</code> if <code>dsc</code> is <code>null</code>.

     *

     * @see java.awt.event.InputEvent

     * @see DragSourceEvent#getLocation

     */

    public DragSourceDragEvent(DragSourceContext dsc, int dropAction,

                               int action, int modifiers) {

        super(dsc);

        targetActions    = action;

        gestureModifiers = modifiers;

        this.dropAction  = dropAction;

        if ((modifiers & ~(JDK_1_3_MODIFIERS | JDK_1_4_MODIFIERS)) != 0) {

            invalidModifiers = true;

        } else if ((getGestureModifiers() != 0) && (getGestureModifiersEx() == 0)) {

            setNewModifiers();

        } else if ((getGestureModifiers() == 0) && (getGestureModifiersEx() != 0)) {

            setOldModifiers();

        } else {

            invalidModifiers = true;

        }

    }

    /**

     * Constructs a <code>DragSourceDragEvent</code> given the specified

     * <code>DragSourceContext</code>, user drop action, target drop action,

     * modifiers and coordinates.

     * <p>

     * The arguments <code>dropAction</code> and <code>action</code> should

     * be one of <code>DnDConstants</code> that represents a single action.

     * The argument <code>modifiers</code> should be either a bitwise mask

     * of old <code>java.awt.event.InputEvent.*_MASK</code> constants or a

     * bitwise mask of extended <code>java.awt.event.InputEvent.*_DOWN_MASK</code>

     * constants.

     * This constructor does not throw any exception for invalid <code>dropAction</code>,

     * <code>action</code> and <code>modifiers</code>.

     *

     * @param dsc the <code>DragSourceContext</code> associated with this

     *        event.

     * @param dropAction the user drop action.

     * @param action the target drop action.

     * @param modifiers the modifier keys down during event (shift, ctrl,

     *        alt, meta)

     *        Either extended _DOWN_MASK or old _MASK modifiers

     *        should be used, but both models should not be mixed

     *        in one event. Use of the extended modifiers is

     *        preferred.

     * @param x   the horizontal coordinate for the cursor location

     * @param y   the vertical coordinate for the cursor location

     *

     * @throws <code>IllegalArgumentException</code> if <code>dsc</code> is <code>null</code>.

     *

     * @see java.awt.event.InputEvent

     * @since 1.4

     */

    public DragSourceDragEvent(DragSourceContext dsc, int dropAction,

                               int action, int modifiers, int x, int y) {

        super(dsc, x, y);

        targetActions    = action;

        gestureModifiers = modifiers;

        this.dropAction  = dropAction;

        if ((modifiers & ~(JDK_1_3_MODIFIERS | JDK_1_4_MODIFIERS)) != 0) {

            invalidModifiers = true;

        } else if ((getGestureModifiers() != 0) && (getGestureModifiersEx() == 0)) {

            setNewModifiers();

        } else if ((getGestureModifiers() == 0) && (getGestureModifiersEx() != 0)) {

            setOldModifiers();

        } else {

            invalidModifiers = true;

        }

    }

    /**

     * This method returns the target drop action.

     *

     * @return the target drop action.

     */

    public int getTargetActions() {

        return targetActions;

    }

    private static final int JDK_1_3_MODIFIERS = InputEvent.SHIFT_DOWN_MASK - 1;

    private static final int JDK_1_4_MODIFIERS =

            ((InputEvent.ALT_GRAPH_DOWN_MASK << 1) - 1) & ~JDK_1_3_MODIFIERS;

    /**

     * This method returns an <code>int</code> representing

     * the current state of the input device modifiers

     * associated with the user's gesture. Typically these

     * would be mouse buttons or keyboard modifiers.

     * <P>

     * If the <code>modifiers</code> passed to the constructor

     * are invalid, this method returns them unchanged.

     *

     * @return the current state of the input device modifiers

     */

    public int getGestureModifiers() {

        return invalidModifiers ? gestureModifiers : gestureModifiers & JDK_1_3_MODIFIERS;

    }

    /**

     * This method returns an <code>int</code> representing

     * the current state of the input device extended modifiers

     * associated with the user's gesture.

     * See {@link InputEvent#getModifiersEx}

     * <P>

     * If the <code>modifiers</code> passed to the constructor

     * are invalid, this method returns them unchanged.

     *

     * @return the current state of the input device extended modifiers

     * @since 1.4

     */

    public int getGestureModifiersEx() {

        return invalidModifiers ? gestureModifiers : gestureModifiers & JDK_1_4_MODIFIERS;

    }

    /**

     * This method returns the user drop action.

     *

     * @return the user drop action.

     */

    public int getUserAction() { return dropAction; }

    /**

     * This method returns the logical intersection of

     * the target drop action and the set of drop actions supported by

     * the drag source.

     *

     * @return the logical intersection of the target drop action and

     *         the set of drop actions supported by the drag source.

     */

    public int getDropAction() {

        return targetActions & getDragSourceContext().getSourceActions();

    }

    /*

     * fields

     */

    /**

     * The target drop action.

     *

     * @serial

     */

    private int     targetActions    = DnDConstants.ACTION_NONE;

    /**

     * The user drop action.

     *

     * @serial

     */

    private int     dropAction       = DnDConstants.ACTION_NONE;

    /**

     * The state of the input device modifiers associated with the user

     * gesture.

     *

     * @serial

     */

    private int     gestureModifiers = 0;

    /**

     * Indicates whether the <code>gestureModifiers</code> are invalid.

     *

     * @serial

     */

    private boolean invalidModifiers;

    /**

     * Sets new modifiers by the old ones.

     * The mouse modifiers have higher priority than overlaying key

     * modifiers.

     */

    private void setNewModifiers() {

        if ((gestureModifiers & InputEvent.BUTTON1_MASK) != 0) {

            gestureModifiers |= InputEvent.BUTTON1_DOWN_MASK;

        }

        if ((gestureModifiers & InputEvent.BUTTON2_MASK) != 0) {

            gestureModifiers |= InputEvent.BUTTON2_DOWN_MASK;

        }

        if ((gestureModifiers & InputEvent.BUTTON3_MASK) != 0) {

            gestureModifiers |= InputEvent.BUTTON3_DOWN_MASK;

        }

        if ((gestureModifiers & InputEvent.SHIFT_MASK) != 0) {

            gestureModifiers |= InputEvent.SHIFT_DOWN_MASK;

        }

        if ((gestureModifiers & InputEvent.CTRL_MASK) != 0) {

            gestureModifiers |= InputEvent.CTRL_DOWN_MASK;

        }

        if ((gestureModifiers & InputEvent.ALT_GRAPH_MASK) != 0) {

            gestureModifiers |= InputEvent.ALT_GRAPH_DOWN_MASK;

        }

    }

    /**

     * Sets old modifiers by the new ones.

     */

    private void setOldModifiers() {

        if ((gestureModifiers & InputEvent.BUTTON1_DOWN_MASK) != 0) {

            gestureModifiers |= InputEvent.BUTTON1_MASK;

        }

        if ((gestureModifiers & InputEvent.BUTTON2_DOWN_MASK) != 0) {

            gestureModifiers |= InputEvent.BUTTON2_MASK;

        }

        if ((gestureModifiers & InputEvent.BUTTON3_DOWN_MASK) != 0) {

            gestureModifiers |= InputEvent.BUTTON3_MASK;

        }

        if ((gestureModifiers & InputEvent.SHIFT_DOWN_MASK) != 0) {

            gestureModifiers |= InputEvent.SHIFT_MASK;

        }

        if ((gestureModifiers & InputEvent.CTRL_DOWN_MASK) != 0) {

            gestureModifiers |= InputEvent.CTRL_MASK;

        }

        if ((gestureModifiers & InputEvent.ALT_GRAPH_DOWN_MASK) != 0) {

            gestureModifiers |= InputEvent.ALT_GRAPH_MASK;

        }

    }

}