/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.resource.ImageRegistry;
import org.eclipse.ui.internal.util.PrefUtil;
import org.eclipse.ui.plugin.AbstractUIPlugin;
import org.osgi.framework.BundleContext;

/**
 * The plug-in class for the org.eclipse.ui plug-in.
 * This class is internal to the workbench and should not be
 * referenced by clients.
 */
public final class UIPlugin extends AbstractUIPlugin {

    private static UIPlugin inst;

    /**
     * Creates an instance of the UIPlugin.
     * 
     * @since 3.0
     */
    public UIPlugin() {
        super();
        inst = this;
    }

    /**
     * Returns the image registry for this plugin.
     *
     * Where are the images?  The images (typically gifs) are found in the 
     * same plugins directory.
     *
     * @see ImageRegistry
     *
     * Note: The workbench uses the standard JFace ImageRegistry to track its images. In addition 
     * the class WorkbenchGraphicResources provides convenience access to the graphics resources 
     * and fast field access for some of the commonly used graphical images.
     */
    protected ImageRegistry createImageRegistry() {
        /* Just to be sure that we don't access this
         * plug-ins image registry.
         */
        Assert.isLegal(false);
        return null;
    }

    public ImageRegistry getImageRegistry() {
        /* Just to be sure that we don't access this
         * plug-ins image registry.
         */
        Assert.isLegal(false);
        return null;
    }

    /**
     * Returns the default instance of the receiver. This represents the runtime plugin.
     *
     * @return UIPlugin the singleton instance of the receiver.
     * @see AbstractUIPlugin for the typical implementation pattern for plugin classes.
     */
    public static UIPlugin getDefault() {
        return inst;
    }

    /** 
     * Set default preference values.
     * This method must be called whenever the preference store is initially loaded
     * because the default values are not stored in the preference store.
     */
    protected void initializeDefaultPreferences(IPreferenceStore store) {
        // Do nothing.  This should not be called.
        // Prefs are initialized in UIPreferenceInitializer.
    }

    /* (non-Javadoc)
     * @see org.eclipse.ui.plugin.AbstractUIPlugin#start(org.osgi.framework.BundleContext)
     */
    public void start(BundleContext context) throws Exception {
        super.start(context);

        // set a callback allowing the workbench plugin to obtain
        // and save the UI plugin's preference store
        PrefUtil.setUICallback(new PrefUtil.ICallback() {
            public IPreferenceStore getPreferenceStore() {
                return UIPlugin.this.getPreferenceStore();
            }

            public void savePreferences() {
                UIPlugin.this.savePluginPreferences();
            }
        });
    }
}