001/*
002 * This library is part of OpenCms -
003 * the Open Source Content Management System
004 *
005 * Copyright (C) Alkacon Software (http://www.alkacon.com)
006 *
007 * This library is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * This library is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * For further information about Alkacon Software, please see the
018 * company website: http://www.alkacon.com
019 *
020 * For further information about OpenCms, please see the
021 * project website: http://www.opencms.org
022 *
023 * You should have received a copy of the GNU Lesser General Public
024 * License along with this library; if not, write to the Free Software
025 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
026 */
027
028package org.opencms.acacia.client.ui;
029
030import org.opencms.acacia.client.CmsChoiceMenuEntryBean;
031import org.opencms.acacia.client.css.I_CmsLayoutBundle;
032
033import com.google.gwt.core.client.Scheduler;
034import com.google.gwt.core.client.Scheduler.ScheduledCommand;
035import com.google.gwt.dom.client.Element;
036import com.google.gwt.dom.client.Style;
037import com.google.gwt.dom.client.Style.Unit;
038import com.google.gwt.user.client.Window;
039import com.google.gwt.user.client.ui.Composite;
040import com.google.gwt.user.client.ui.FlowPanel;
041
042/**
043 * A choice submenu widget.<p>
044 */
045public class CmsChoiceSubmenu extends Composite {
046
047    /** The composite widget. */
048    private FlowPanel m_root = new FlowPanel();
049
050    /**
051     * Creates a new submenu.<p>
052     *
053     * @param parentEntry the parent menu entry bean
054     */
055    public CmsChoiceSubmenu(CmsChoiceMenuEntryBean parentEntry) {
056
057        initWidget(m_root);
058        addStyleName(I_CmsLayoutBundle.INSTANCE.attributeChoice().choices());
059        addStyleName(I_CmsLayoutBundle.INSTANCE.attributeChoice().submenu());
060    }
061
062    /**
063     * Adds a new choice widget.<p>
064     *
065     * @param choice the choice widget
066     */
067    public void addChoice(CmsChoiceMenuEntryWidget choice) {
068
069        m_root.add(choice);
070    }
071
072    /**
073     * Checks whether the submenu should be opened above instead of below.<p>
074     *
075     * @param referenceElement the reference element
076     * @return true if the new submenu should be opened above
077     */
078    public boolean openAbove(Element referenceElement) {
079
080        int windowTop = Window.getScrollTop();
081        int windowBottom = Window.getScrollTop() + Window.getClientHeight();
082        int spaceAbove = referenceElement.getAbsoluteTop() - windowTop;
083        int spaceBelow = windowBottom - referenceElement.getAbsoluteBottom();
084        return spaceAbove > spaceBelow;
085    }
086
087    /**
088     * Positions a new submenu asynchronously.<p>
089     *
090     * @param widgetEntry the menu entry relative to which the submenu should be positioned
091     */
092    public void positionDeferred(final CmsChoiceMenuEntryWidget widgetEntry) {
093
094        getElement().getStyle().setPosition(Style.Position.ABSOLUTE);
095        getElement().getStyle().setVisibility(Style.Visibility.HIDDEN);
096        Scheduler.get().scheduleDeferred(new ScheduledCommand() {
097
098            public void execute() {
099
100                positionNextToMenuEntry(widgetEntry);
101                getElement().getStyle().setVisibility(Style.Visibility.VISIBLE);
102            }
103
104        });
105    }
106
107    /**
108     * Helper method to position a submenu on the left side of a menu entry.<p>
109     *
110     * @param widgetEntry the widget entry relative to which the submenu should  be positioned
111     */
112    protected void positionNextToMenuEntry(final CmsChoiceMenuEntryWidget widgetEntry) {
113
114        Element elem = getElement();
115        elem.getStyle().setPosition(Style.Position.ABSOLUTE);
116        Element referenceElement = null;
117        int startX = -2000;
118        int startY = -2000;
119        int deltaX = 0;
120        int deltaY = 0;
121        referenceElement = widgetEntry.getElement();
122        Style style = elem.getStyle();
123        style.setLeft(startX, Unit.PX);
124        style.setTop(startY, Unit.PX);
125        int myRight = elem.getAbsoluteRight();
126        int myTop = elem.getAbsoluteTop();
127        int refLeft = referenceElement.getAbsoluteLeft();
128        int refTop = referenceElement.getAbsoluteTop();
129        int newLeft = startX + (refLeft - myRight) + deltaX;
130        int newTop;
131        if (openAbove(referenceElement)) {
132            int myHeight = elem.getOffsetHeight();
133            int refHeight = referenceElement.getOffsetHeight();
134            newTop = startY + ((refTop + refHeight) - (myTop + myHeight)) + deltaY;
135        } else {
136            newTop = startY + (refTop - myTop) + deltaY;
137        }
138        style.setLeft(newLeft, Unit.PX);
139        style.setTop(newTop, Unit.PX);
140    }
141
142}