src/plugins/db.core/src/com/motorolamobility/studio/android/db/core/ui/LoadingJobListener.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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 com.motorolamobility.studio.android.db.core.ui;

import java.util.List;

import org.eclipse.core.runtime.jobs.IJobChangeEvent;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.core.runtime.jobs.JobChangeAdapter;
import org.eclipse.jface.viewers.ILazyTreeContentProvider;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.swt.widgets.Display;

import com.motorola.studio.android.common.utilities.PluginUtils;
import com.motorolamobility.studio.android.db.core.DbCoreActivator;
import com.motorolamobility.studio.android.db.core.ui.view.MOTODEVDatabaseExplorerView;

/**
 * This class is responsible to set the loading attribute on a tree node when a loadingJob is scheduled and set it to false
 *  before updating the treeView after the loadingJob finished execution.
 * The node child count is update on job done. TreeView contentProvider will take care of the rest.
 */
public final class LoadingJobListener extends JobChangeAdapter
{
    /* (non-Javadoc)
     * @see org.eclipse.core.runtime.jobs.JobChangeAdapter#scheduled(org.eclipse.core.runtime.jobs.IJobChangeEvent)
     */
    @Override
    public void scheduled(IJobChangeEvent event)
    {
        Job job = event.getJob();
        if (job instanceof AbstractLoadingNodeJob)
        {
            AbstractLoadingNodeJob loadingNodeJob = (AbstractLoadingNodeJob) job;
            ITreeNode node = loadingNodeJob.getNode();

            //Since load job has been scheduled, the loading flag must be set to true (This will help the content provider to show the loading node).
            node.setLoading(true);
        }
        super.scheduled(event);
    }

    /* (non-Javadoc)
     * @see org.eclipse.core.runtime.jobs.JobChangeAdapter#done(org.eclipse.core.runtime.jobs.IJobChangeEvent)
     */
    @Override
    public void done(IJobChangeEvent event)
    {
        MOTODEVDatabaseExplorerView view = DbCoreActivator.getMOTODEVDatabaseExplorerView();
        if (view != null)
        {
            final TreeViewer treeViewer = view.getTreeViewer();
            Job job = event.getJob();
            if (job instanceof AbstractLoadingNodeJob)
            {
                AbstractLoadingNodeJob loadingNodeJob = (AbstractLoadingNodeJob) job;
                ITreeNode node = loadingNodeJob.getNode();

                //Job is done, so we can set the loading flag to false.
                node.setLoading(false);
                final ITreeNode[] treeNodeContainer =
                {
                    node
                };

                //TreeViewer operations must be executed on the UI Thread.
                Display.getDefault().syncExec(new Runnable()
                {
                    public void run()
                    {
                        ITreeNode node = treeNodeContainer[0];
                        List<ITreeNode> children = node.getChildren();
                        if (PluginUtils.getOS() != PluginUtils.OS_LINUX)
                        {
                            treeViewer.setChildCount(node, 0);
                        }
                        int size = children.size();
                        if (size > 0)
                        {
                            ((ILazyTreeContentProvider) treeViewer.getContentProvider())
                                    .updateElement(node, 0); //Force removal of loading node.
                        }
                        //updating the child count is sufficient to allow the tree to call the content provider and retrieve the new nodes.
                        treeViewer.setChildCount(node, size);
                        //updating the node so if needed the label/icon will be updated
                        treeViewer.update(node, null);
                    }
                });
            }
            super.done(event);
        }
    }
}