Java tutorial
/******************************************************************************* * Copyright (c) 2006 Sybase, Inc. and others. * * 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: * Sybase, Inc. - initial API and implementation *******************************************************************************/ package org.eclipse.jst.jsf.common.ui.internal.utils; import java.util.HashMap; import org.eclipse.jface.resource.ImageDescriptor; import org.eclipse.jface.resource.ImageRegistry; import org.eclipse.jface.resource.JFaceResources; import org.eclipse.swt.graphics.Image; import org.eclipse.ui.plugin.AbstractUIPlugin; /** * @author mengbo */ public class PluginImageHelper { private static PluginImageHelper _instance = null; /** * Gets the instance. * * @return Returns a TaglibPluginImageHelper */ public synchronized static PluginImageHelper getInstance() { if (_instance == null) { _instance = new PluginImageHelper(); } return _instance; } // save a descriptor for each image private HashMap _imageDescRegistry = null; private final String PLUGIN_SEPARATOR = "^"; //$NON-NLS-1$ /** * Creates an image from the given resource and adds the image to the image * registry. * * @param resource * @param pluginId * @return Image */ private Image createImage(String resource, String pluginId) { ImageDescriptor desc = getImageDescriptor(resource, pluginId); Image image = null; if (desc != null) { image = desc.createImage(); // dont add the missing image descriptor image to the image // registry if (!desc.equals(ImageDescriptor.getMissingImageDescriptor())) { String thePluginId = pluginId; if (thePluginId == null) { return null; } String key = thePluginId + PLUGIN_SEPARATOR + resource; getImageRegistry().put(key, image); } } return image; } /** * Creates an image descriptor from the given imageFilePath in the given * pluginId and adds the image descriptor to the image descriptor registry. * If an image descriptor could not be created, the default "missing" image * descriptor is returned but not added to the image descriptor registry. * * @param imageFilePath * @param pluginId * if null, look in this plugin * @return ImageDescriptor image descriptor for imageFilePath or default * "missing" image descriptor if resource could not be found */ private ImageDescriptor createImageDescriptor(String imageFilePath, String pluginId) { String thePluginId = pluginId; if (thePluginId == null) { return null; } ImageDescriptor imageDescriptor = AbstractUIPlugin.imageDescriptorFromPlugin(thePluginId, imageFilePath); if (imageDescriptor != null) { String key = thePluginId + PLUGIN_SEPARATOR + imageFilePath; getImageDescriptorRegistry().put(key, imageDescriptor); } else { imageDescriptor = ImageDescriptor.getMissingImageDescriptor(); } return imageDescriptor; } /** * Retrieves the image associated with resource from the image registry. If * the image cannot be retrieved, attempt to find and load the image at the * location specified in resource. * * @param resource * the image to retrieve * @return Image the image associated with resource or null if one could not * be found */ public Image getImage(String resource) { return getImage(resource, null); } /** * Retrieves the image associated with resource from the image registry. If * the image cannot be retrieved, attempt to find and load the image at the * location specified in resource. * * @param resource * the image to retrieve * @param pluginId * @return Image the image associated with resource or null if one could not * be found */ public Image getImage(String resource, String pluginId) { String thePluginId = pluginId; if (thePluginId == null) { return null; } String key = thePluginId + PLUGIN_SEPARATOR + resource; Image image = getImageRegistry().get(key); if (image == null) { // create an image image = createImage(resource, pluginId); } return image; } /** * Retrieves the image descriptor associated with resource from the image * descriptor registry. If the image descriptor cannot be retrieved, attempt * to find and load the image descriptor at the location specified in * resource. * * @param resource * the image descriptor to retrieve * @return ImageDescriptor the image descriptor assocated with resource or * the default "missing" image descriptor if one could not be found */ public ImageDescriptor getImageDescriptor(String resource) { return getImageDescriptor(resource, null); } /** * Retrieves the image descriptor associated with resource in pluginId from * the image descriptor registry. If the image descriptor cannot be * retrieved, attempt to find and load the image descriptor at the location * specified in resource in pluginId. * * @param resource * the image descriptor to retrieve * @param pluginId * the plugin the resource is located. if null, use look in this * plugin * @return ImageDescriptor the image descriptor assocated with resource or * the default "missing" image descriptor if one could not be found */ public ImageDescriptor getImageDescriptor(String resource, String pluginId) { ImageDescriptor imageDescriptor = null; String thePluginId = pluginId; if (thePluginId == null) { return null; } String key = thePluginId + PLUGIN_SEPARATOR + resource; Object o = getImageDescriptorRegistry().get(key); if (o == null) { // create a descriptor imageDescriptor = createImageDescriptor(resource, pluginId); } else { imageDescriptor = (ImageDescriptor) o; } return imageDescriptor; } /** * Returns the image descriptor registry for this plugin. * * @return HashMap - image descriptor registry for this plugin */ private HashMap getImageDescriptorRegistry() { if (_imageDescRegistry == null) { _imageDescRegistry = new HashMap(); } return _imageDescRegistry; } /** * Returns the image registry for this plugin. * * @return ImageRegistry - image registry for this plugin */ private ImageRegistry getImageRegistry() { return JFaceResources.getImageRegistry(); } }