Java tutorial
/* * Copyright (c) 1997, 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 java.awt.dnd; import java.awt.event.InputEvent; /** * The {@code DragSourceDragEvent} is * delivered from the {@code DragSourceContextPeer}, * via the {@code DragSourceContext}, to the {@code DragSourceListener} * registered with that {@code DragSourceContext} and with its associated * {@code DragSource}. * <p> * The {@code DragSourceDragEvent} 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} 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} 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} that represents the selected drop action if this * drop action is supported by the drag source or * {@code DnDConstants.ACTION_NONE} 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} that represents the set of drop actions supported * by the drag source is searched for {@code DnDConstants.ACTION_MOVE}, * then for {@code DnDConstants.ACTION_COPY}, then for * {@code DnDConstants.ACTION_LINK} 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}. * * @since 1.2 * */ public class DragSourceDragEvent extends DragSourceEvent { private static final long serialVersionUID = 481346297933902471L; /** * Constructs a {@code DragSourceDragEvent}. * This class is typically * instantiated by the {@code DragSourceContextPeer} * rather than directly * by client code. * The coordinates for this {@code DragSourceDragEvent} * are not specified, so {@code getLocation} will return * {@code null} for this event. * <p> * The arguments {@code dropAction} and {@code action} should * be one of {@code DnDConstants} that represents a single action. * The argument {@code modifiers} should be either a bitwise mask * of old {@code java.awt.event.InputEvent.*_MASK} constants or a * bitwise mask of extended {@code java.awt.event.InputEvent.*_DOWN_MASK} * constants. * This constructor does not throw any exception for invalid {@code dropAction}, * {@code action} and {@code modifiers}. * * @param dsc the {@code DragSourceContext} 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 IllegalArgumentException if {@code dsc} is {@code null}. * * @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} given the specified * {@code DragSourceContext}, user drop action, target drop action, * modifiers and coordinates. * <p> * The arguments {@code dropAction} and {@code action} should * be one of {@code DnDConstants} that represents a single action. * The argument {@code modifiers} should be either a bitwise mask * of old {@code java.awt.event.InputEvent.*_MASK} constants or a * bitwise mask of extended {@code java.awt.event.InputEvent.*_DOWN_MASK} * constants. * This constructor does not throw any exception for invalid {@code dropAction}, * {@code action} and {@code modifiers}. * * @param dsc the {@code DragSourceContext} 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 IllegalArgumentException if {@code dsc} is {@code null}. * * @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} 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} 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} 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} 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} are invalid. * * @serial */ private boolean invalidModifiers; /** * Sets new modifiers by the old ones. * The mouse modifiers have higher priority than overlaying key * modifiers. */ @SuppressWarnings("deprecation") 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. */ @SuppressWarnings("deprecation") 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; } } }