Java tutorial
/* * This library is part of the Acacia Editor - * an open source inline and form based content editor for GWT. * * Copyright (c) Alkacon Software GmbH (http://www.alkacon.com) * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library 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 * Lesser General Public License for more details. * * For further information about Alkacon Software, please see the * company website: http://www.alkacon.com * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ package com.alkacon.acacia.client.ui; import com.alkacon.acacia.client.ButtonBarHandler; import com.alkacon.acacia.client.ChoiceMenuEntryBean; import com.alkacon.acacia.client.I_WidgetService; import com.alkacon.acacia.client.css.I_LayoutBundle; import com.google.gwt.core.client.GWT; import com.google.gwt.dom.client.SpanElement; import com.google.gwt.event.dom.client.HasMouseOutHandlers; import com.google.gwt.event.dom.client.HasMouseOverHandlers; import com.google.gwt.event.dom.client.MouseOutEvent; import com.google.gwt.event.dom.client.MouseOutHandler; import com.google.gwt.event.dom.client.MouseOverEvent; import com.google.gwt.event.dom.client.MouseOverHandler; import com.google.gwt.event.shared.HandlerRegistration; import com.google.gwt.uibinder.client.UiBinder; import com.google.gwt.uibinder.client.UiField; import com.google.gwt.user.client.Window; import com.google.gwt.user.client.rpc.AsyncCallback; import com.google.gwt.user.client.ui.Composite; import com.google.gwt.user.client.ui.FlowPanel; import com.google.gwt.user.client.ui.HTMLPanel; import com.google.gwt.user.client.ui.Panel; import com.google.gwt.user.client.ui.Widget; /** * The attribute choice widget.<p> */ public class AttributeChoiceWidget extends Composite implements HasMouseOverHandlers, HasMouseOutHandlers { /** * The UI binder interface.<p> */ interface AttributeChoiceWidgetUiBinder extends UiBinder<HTMLPanel, AttributeChoiceWidget> { // nothing to do } /** The UI binder instance. */ private static AttributeChoiceWidgetUiBinder uiBinder = GWT.create(AttributeChoiceWidgetUiBinder.class); /** The button icon element. */ @UiField SpanElement m_buttonIcon; /** The choices panel. */ @UiField FlowPanel m_choices; /** * Constructor.<p> */ public AttributeChoiceWidget() { initWidget(uiBinder.createAndBindUi(this)); addMouseOutHandler(ButtonBarHandler.INSTANCE); addMouseOverHandler(ButtonBarHandler.INSTANCE); } /** * Adds a new choice entry.<p> * * @param widgetService the widget service to use for labels * @param menuEntry the menu entry bean * @param selectHandler the handler to use for selecting entries */ public void addChoice(I_WidgetService widgetService, ChoiceMenuEntryBean menuEntry, AsyncCallback<ChoiceMenuEntryBean> selectHandler) { Widget choice = new ChoiceMenuEntryWidget(widgetService.getAttributeLabel(menuEntry.getPathComponent()), widgetService.getAttributeHelp(menuEntry.getPathComponent()), menuEntry, selectHandler, this, null); addChoice(choice); } /** * Adds a choice to the widget.<p> * * @param choice the choice to add */ public void addChoice(Widget choice) { choice.setStyleName(I_LayoutBundle.INSTANCE.attributeChoice().choice()); m_choices.add(choice); } /** * @see com.google.gwt.event.dom.client.HasMouseOutHandlers#addMouseOutHandler(com.google.gwt.event.dom.client.MouseOutHandler) */ public HandlerRegistration addMouseOutHandler(MouseOutHandler handler) { return addDomHandler(handler, MouseOutEvent.getType()); } /** * @see com.google.gwt.event.dom.client.HasMouseOverHandlers#addMouseOverHandler(com.google.gwt.event.dom.client.MouseOverHandler) */ public HandlerRegistration addMouseOverHandler(MouseOverHandler handler) { return addDomHandler(handler, MouseOverEvent.getType()); } /** * Gets the panel into which submenus of this menu should be inserted.<p> * * @return the panel for submenus */ public Panel getSubmenuPanel() { return (Panel) getParent(); } /** * Hides the choice menu.<p> */ public void hide() { removeStyleName(I_LayoutBundle.INSTANCE.attributeChoice().hovering()); } /** * Shows the choice menu.<p> */ public void show() { addStyleName(I_LayoutBundle.INSTANCE.attributeChoice().hovering()); if (displayAbove()) { addStyleName(I_LayoutBundle.INSTANCE.attributeChoice().displayAbove()); } else { removeStyleName(I_LayoutBundle.INSTANCE.attributeChoice().displayAbove()); } } /** * Evaluates if the choice select should be displayed above the button.<p> * * @return <code>true</code> if the choice select should be displayed above the button */ private boolean displayAbove() { int popupHeight = m_choices.getOffsetHeight(); // Calculate top position for the choice select int top = m_buttonIcon.getAbsoluteTop(); // Make sure scrolling is taken into account, since // box.getAbsoluteTop() takes scrolling into account. int windowTop = Window.getScrollTop(); int windowBottom = Window.getScrollTop() + Window.getClientHeight(); // Distance from the top edge of the window to the top edge of the // text box int distanceFromWindowTop = top - windowTop; // Distance from the bottom edge of the window to the bottom edge of // the text box int distanceToWindowBottom = windowBottom - (top + m_buttonIcon.getOffsetHeight()); // If there is not enough space for the popup's height below the button // and there IS enough space for the popup's height above the button, // then then position the popup above the button. However, if there // is not enough space on either side, then stick with displaying the // popup below the button. boolean displayAbove = (distanceFromWindowTop > distanceToWindowBottom) && (distanceToWindowBottom < popupHeight); return displayAbove; } }