Java tutorial
/* * Copyright 2008 Eckhart Arnold (eckhart_arnold@hotmail.com). * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ package de.eckhartarnold.client; import com.google.gwt.core.client.GWT; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.event.logical.shared.ResizeEvent; import com.google.gwt.event.logical.shared.ValueChangeEvent; import com.google.gwt.event.logical.shared.ValueChangeHandler; import com.google.gwt.user.client.History; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.ui.Panel; /** * Ties together the gallery and the * slide show. * * <p>The user can switch between the gallery and * the slide show by clicking on a picture or on the "start slide show" * button in the gallery, or by clicking on the gallery button of the * control panel in the slide show. * * <p>Thus, class <code>GalleryPresentation</code> selects between two types * of web pages, the "gallery page" and the "slide show page". The * "slide show page" is selected when a pick image or start slide show event * is received or when an the "slide show page" for a particular image is * found on top of the browser history. The "gallery page" is selected * when an <code>onClick</code> event is received * (usually from the gallery button on the control panel) or when a gallery * token is at top of the browser history or when none of the previous * conditions for selecting either the "slide show page" or the "gallery page" * holds. * * @author ecki * */ public class GalleryPresentation extends Presentation implements GalleryListener, ClickHandler, ValueChangeHandler<String>, SlideshowListener { /** The gallery widget that makes up the gallery page */ protected GalleryBase gallery; /** true, if the slideshow has been started from the gallery page; in this * case the slideshow will return to the gallery page after finishing. */ private boolean slideshowInitiated = false; /** * The constructor of class <code>GalleryPresentation</code>. * * @param parent the parent widget of the gallery and the slide show * respectively * @param gallery the gallery widget * @param layout the layout that contains the slide show */ public GalleryPresentation(Panel parent, GalleryBase gallery, Layout layout) { super(parent, layout); this.gallery = gallery; layout.setHomeButtonListener(this); gallery.addGalleryListener(this); layout.slideshow.addSlideshowListener(this); int imageNr = Presentation.parseSlideToken(History.getToken()); if (imageNr < 0) { parent.add(gallery); } else onPickImage(imageNr); History.addValueChangeHandler(this); Debugger.consoleLog("GWTPhotoAlbum started"); } /** * Reports whether the gallery page is active at the moment. * @return <code>true</code> if gallery page is active and * <code>false</code> if the slide show page is active */ public boolean isGalleryActive() { return !slideshowActive; } /** * This method ought to be called in order to request a switch to * the gallery page. * * @param event a click event This may also be <code>null</code> * if the caller is not a widget object. */ public void onClick(ClickEvent event) { returnToGallery(); } /* (non-Javadoc) * @see com.google.gwt.event.logical.shared.ValueChangeHandler#onValueChange(com.google.gwt.event.logical.shared.ValueChangeEvent) */ @Override public void onValueChange(ValueChangeEvent<String> event) { String historyToken = event.getValue(); GWT.log("GalleryPresentation.onValueChanged: " + historyToken); if (historyToken.equals(GalleryBase.GALLERY_TOKEN)) { if (slideshowActive) { onClick(null); } } else if (slideshowActive) { super.onValueChange(event); } else { int slideNr = Presentation.parseSlideToken(historyToken); if (slideNr >= 0) { onPickImage(slideNr); } else { History.back(); } } } /* (non-Javadoc) * @see de.eckhartarnold.client.GalleryListener#onPickImage(int) */ public void onPickImage(int imageNr) { parent.remove(gallery); layout.getSlideshow().show(-1); layout.getSlideshow().showImmediately(imageNr); activateSlideshow(); } /* (non-Javadoc) * @see de.eckhartarnold.client.GalleryListener#onStartSlideshow() */ public void onStartSlideshow() { parent.remove(gallery); layout.getSlideshow().show(-1); activateSlideshow(); slideshowInitiated = true; layout.getSlideshow().start(); } /* (non-Javadoc) * @see com.google.gwt.event.logical.shared.ResizeHandler#onResize(com.google.gwt.event.logical.shared.ResizeEvent) */ public void onResize(ResizeEvent event) { if (isGalleryActive()) { gallery.onResized(); } else { super.onResize(event); } } /* (non-Javadoc) * @see de.eckhartarnold.client.SlideshowListener#onFade() */ public void onFade() { } /* (non-Javadoc) * @see de.eckhartarnold.client.SlideshowListener#onShow() */ public void onShow(int slideNr) { } /* (non-Javadoc) * @see de.eckhartarnold.client.SlideshowListener#onStart() */ public void onStart() { } /* (non-Javadoc) * @see de.eckhartarnold.client.SlideshowListener#onStop() */ public void onStop() { if (layout.slideshow.getCurrentSlide() == layout.slideshow.size() - 1) { Timer timer = new Timer() { public void run() { if (slideshowInitiated) { returnToGallery(); } } }; timer.schedule(layout.slideshow.getDuration() * 120 / 100); // let the last image stay a little longer... } else { slideshowInitiated = false; } } /** * Switches back to the gallery if slideshow is active */ private void returnToGallery() { if (slideshowActive) { slideshowInitiated = false; deactivateSlideshow(); parent.add(gallery); } } }