Java tutorial
/******************************************************************************* * Copyright (c) 2012 Google, Inc. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Google, Inc. - initial API and implementation *******************************************************************************/ package com.windowtester.swt.util; import java.net.MalformedURLException; import java.net.URL; import org.eclipse.jface.action.IAction; import org.eclipse.jface.resource.ImageDescriptor; import org.eclipse.jface.resource.ImageRegistry; import org.eclipse.swt.graphics.Image; /** * Manages the images and image descriptors implementing an efficient cache. This * implementations caches these objects in a {@link org.eclipse.jface.resource.ImageRegistry} * instance. * * <p>Before using an instance of this class it is necessary to invoke the * {@link #initialize()} method. * * <p>This implementation is based on the * {@link org.eclipse.jdt.internal.ui.JavaPluginImages} class. */ abstract public class ImageManager { /* * Image directory prefixes. */ public static final String T_LCL = "lcl16"; public static final String T_TOOL = "tool16"; public static final String T_VIEW = "view16"; public static final String T_OBJ = "obj16"; public static final String T_OVR = "ovr16"; public static final String T_WIZBAN = "wizban"; /** * URL to the plugin's icon base directory. */ private URL iconBaseURL; /** * Image registry used to cache the images and image descriptors. */ private ImageRegistry imageRegistry; /** * Indicates if the images were loaded to this image manager. */ private boolean imagesWereLoaded = false; /** * Initializes this image manager. Nothing happens if this method is * invoked after a previous initialization. * * <p>This method is not supposed to be invoked more than once. * * @param iconBaseURL The url to the plugin's icon base directory. * @param imageRegistry The image registry to cache the images and image * descriptors. */ public void initialize(URL iconBaseURL, ImageRegistry imageRegistry) { this.iconBaseURL = iconBaseURL; this.imageRegistry = imageRegistry; } /** * Checks if the images are loaded in the cache. The variable * <code>imagesWereLoaded</code> is used to ensure that they won't * be loaded more then once. */ protected void checkImages() { if (imagesWereLoaded) return; addImages(); imagesWereLoaded = true; } /** * Subclasses are supposed to add <b>all</b> the images to this manager in this * method implementation. * * <p>The images should be added by invoking one the <code>add</code> * methods. */ abstract protected void addImages(); /** * Creates an image descriptor for a given image directory prefix and * image name adding it to the image registry. * @param prefix * @param name * @return ImageDescriptor */ protected ImageDescriptor add(String prefix, String name) { ImageDescriptor imageDescriptor = createImageDescriptor(prefix, name); if (imageDescriptor != null && imageRegistry != null) imageRegistry.put(name, imageDescriptor); return imageDescriptor; } /** * Creates an image descriptor for a given image directory prefix, directory * type and image name adding it to the image registry. * * <p>This method is typically used to register action images. For example, to * register <i>clcl16/open.gif</i>, <i>dlcl16/open.gif</i> and <i>elcl16/open.gif</i> * client should execute <pre>addManaged("c", T_LCL, "open.gif")</pre>, * <pre>add("d", T_LCL, "open.gif")</pre> and * <pre>add("e", T_LCL, "open.gif")</pre>. * * @param prefixType * @param prefix * @param name * @return ImageDescriptor */ protected ImageDescriptor add(String prefixType, String prefix, String name) { ImageDescriptor imageDescriptor = createImageDescriptor(prefixType + prefix, name); if (imageDescriptor != null) imageRegistry.put(prefixType + name, imageDescriptor); return imageDescriptor; } /** * Adds an image descriptor to this image manager. * @param key * @param imageDescriptor * @return <code>true</code> if the image descriptor was added of <code>false</code> * if <code>key</code> or <code>imageDescriptor</code> is <code>null</code> or if the * default image registry has already the specified <code>key</code>. * @throws IllegalArgumentException if the key already exists */ protected boolean add(String key, ImageDescriptor imageDescriptor) throws IllegalArgumentException { if ((key == null) || (imageDescriptor == null)) return false; imageRegistry.put(key, imageDescriptor); return true; } /** * Creates an image descriptor for a given image directory prefix and * image name. The image prefix is appended to the * {@link #iconBaseURL base icon url} * @param prefix * @param name * @return ImageDescriptor */ protected ImageDescriptor createImageDescriptor(String prefix, String name) { try { return ImageDescriptor.createFromURL(makeIconFileURL(prefix, name)); } catch (MalformedURLException e) { return ImageDescriptor.getMissingImageDescriptor(); } } /** * Creates a URL for a given image directory prefix and * image name. * @param prefix * @param name * @return URL * @throws MalformedURLException */ protected URL makeIconFileURL(String prefix, String name) throws MalformedURLException { if (iconBaseURL == null) throw new MalformedURLException(); StringBuffer buffer = new StringBuffer(prefix); buffer.append('/'); buffer.append(name); return new URL(iconBaseURL, buffer.toString()); } /** * Returns the image descriptor associated to a key. * @param key * @return ImageDescriptor */ public ImageDescriptor getImageDescriptor(String key) { checkImages(); return imageRegistry.getDescriptor(key); } /** * Returns the image associated to a key. * image registry. * @param key * @return Image */ public Image getImage(String key) { checkImages(); return imageRegistry == null ? null : imageRegistry.get(key); } /** * Returns the image descriptor associated to a prefix type and key. The * prefix type is the prefix of the directory such as "c", "d" and "e" in * "cview16", "dview16" and "eview16". * @param prefixType * @param key * @return ImageDescriptor */ public ImageDescriptor getImageDescriptor(String prefixType, String key) { return getImageDescriptor(prefixType + key); } /** * Returns the image associated to a prefix type and key. The * prefix type is the prefix of the directory such as "c", "d" and "e" in * "cview16", "dview16" and "eview16". * @param prefixType * @param key * @return ImageDescriptor */ public Image getImage(String prefixType, String key) { return getImage(prefixType + key); } /** * Sets all the image descriptors of a given action. This method assumes * the following convention:<OL> * <LI>The prefix type "e" is used for the main image</LI> * <LI>The prefix type "c" is used for the hover image</LI> * <LI>The prefix type "d" is used for the disabled image</LI> * </OL> * * @param action * @param name */ public void setImageDescriptors(IAction action, String name) { ImageDescriptor imageDescriptor = getImageDescriptor("d", name); if (imageDescriptor != null) action.setDisabledImageDescriptor(imageDescriptor); imageDescriptor = getImageDescriptor("c", name); if (imageDescriptor != null) action.setHoverImageDescriptor(imageDescriptor); imageDescriptor = getImageDescriptor("e", name); if (imageDescriptor != null) action.setImageDescriptor(imageDescriptor); } }