/*
 * Copyright (c) 2005-2014 JGoodies Software GmbH. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  o Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  o Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 *  o Neither the name of JGoodies Software GmbH nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jgoodies.looks.common;

import java.awt.Component;

import javax.swing.LookAndFeel;
import javax.swing.Popup;
import javax.swing.PopupFactory;

import com.jgoodies.common.base.SystemUtils;
import com.jgoodies.looks.Options;


/**
 * The JGoodies Looks implementation of {@code PopupFactory}.
 * Adds a drop shadow border to all popups except ComboBox popups.
 * It is installed by the JGoodies Plastic L&amp;F, as well as by
 * the JGoodies Windows L&amp;F during the Look&amp;Feel initialization,
 * see {@link com.jgoodies.looks.plastic.PlasticLookAndFeel#initialize} and
 * {@link com.jgoodies.looks.windows.WindowsLookAndFeel#initialize}.<p>
 *
 * This factory shall not be used on platforms that provide native drop shadows,
 * such as the Mac OS X. Therefore the invocation of the {@link #install()}
 * method will have no effect on such platforms.<p>
 *
 * <strong>Note:</strong> To be used in a sandbox environment, this PopupFactory
 * requires two AWT permissions: {@code createRobot} and
 * {@code readDisplayPixels}. The reason for it is, that in the case of
 * the heavy weight popups this PopupFactory uses a Robot to snapshot
 * the screen background to simulate the drop shadow effect.
 *
 * @author Karsten Lentzsch
 * @version $Revision: 1.8 $
 *
 * @see java.awt.AWTPermission
 * @see java.awt.Robot
 * @see javax.swing.Popup
 * @see LookAndFeel#initialize
 * @see LookAndFeel#uninitialize
 */
public final class ShadowPopupFactory extends PopupFactory {

    /**
     * In the case of heavy weight popups, snapshots of the screen background
     * will be stored as client properties of the popup contents' parent.
     * These snapshots will be used by the popup border to simulate the drop
     * shadow effect. The two following constants define the names of
     * these client properties.
     *
     * @see com.jgoodies.looks.common.ShadowPopupBorder
     */
    static final String PROP_HORIZONTAL_BACKGROUND = "jgoodies.hShadowBg";
    static final String PROP_VERTICAL_BACKGROUND   = "jgoodies.vShadowBg";

    /**
     * The PopupFactory used before this PopupFactory has been installed
     * in {@code #install}. Used to restored the original state
     * in {@code #uninstall}.
     */
    private final PopupFactory storedFactory;


    // Instance Creation ******************************************************

    private ShadowPopupFactory(PopupFactory storedFactory) {
        this.storedFactory = storedFactory;
    }


    // API ********************************************************************

    /**
     * Installs the ShadowPopupFactory as the shared popup factory
     * on non-Mac platforms. Also stores the previously set factory,
     * so that it can be restored in {@code #uninstall}.<p>
     *
     * In some Mac Java environments the popup factory throws
     * a NullPointerException when we call {@code #getPopup}.<p>
     *
     * TODO: The Mac case shows that we may have problems replacing
     * non PopupFactory instances. Therefore we should consider
     * replacing only instances of PopupFactory.
     *
     * @see #uninstall()
     */
    public static void install() {
        if (SystemUtils.IS_OS_MAC) {
            return;
        }

        PopupFactory factory = PopupFactory.getSharedInstance();
        if (factory instanceof ShadowPopupFactory) {
            return;
        }

        PopupFactory.setSharedInstance(new ShadowPopupFactory(factory));
    }

    /**
     * Uninstalls the ShadowPopupFactory and restores the original
     * popup factory as the new shared popup factory.
     *
     * @see #install()
     */
    public static void uninstall() {
        PopupFactory factory = PopupFactory.getSharedInstance();
        if (!(factory instanceof ShadowPopupFactory)) {
            return;
        }

        PopupFactory stored = ((ShadowPopupFactory) factory).storedFactory;
        PopupFactory.setSharedInstance(stored);
    }


    /**
     * Creates a {@code Popup} for the Component {@code owner}
     * containing the Component {@code contents}. In addition to
     * the superclass behavior, we try to return a Popup that has a drop shadow,
     * if popup drop shadows are active - as returned by
     * {@code Options#isPopupDropShadowActive}.<p>
     *
     * {@code owner} is used to determine which {@code Window} the new
     * {@code Popup} will parent the {@code Component} the
     * {@code Popup} creates to. A null {@code owner} implies there
     * is no valid parent. {@code x} and
     * {@code y} specify the preferred initial location to place
     * the {@code Popup} at. Based on screen size, or other paramaters,
     * the {@code Popup} may not display at {@code x} and
     * {@code y}.<p>
     *
     * We invoke the super {@code #getPopup}, not the one in the
     * stored factory, because the popup type is set in this instance,
     * not in the stored one.
     *
     * @param owner    Component mouse coordinates are relative to, may be null
     * @param contents Contents of the Popup
     * @param x        Initial x screen coordinate
     * @param y        Initial y screen coordinate
     * @return Popup containing Contents
     * @throws IllegalArgumentException if contents is null
     *
     * @see Options#isPopupDropShadowActive()
     */
    @Override
    public Popup getPopup(Component owner, Component contents, int x, int y) {
        Popup popup = super.getPopup(owner, contents, x, y);
        return Options.isPopupDropShadowActive()
            ? ShadowPopup.getInstance(owner, contents, x, y, popup)
            : popup;
    }

}
