org.polymap.rhei.batik.toolkit.BusyIndicator.java Source code

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Here is the source code for org.polymap.rhei.batik.toolkit.BusyIndicator.java

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/* 
 * polymap.org
 * Copyright (C) 2014, Falko Brutigam. All rights reserved.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 3.0 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 */
package org.polymap.rhei.batik.toolkit;

import java.util.concurrent.Callable;
import java.util.concurrent.atomic.AtomicReference;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;

import org.polymap.rhei.batik.BatikApplication;

/**
 * 
 *
 * @author <a href="http://www.polymap.de">Falko Brutigam</a>
 */
public class BusyIndicator implements IBusyIndicator {

    private static Log log = LogFactory.getLog(BusyIndicator.class);

    private Composite parent;

    public BusyIndicator(Composite parent) {
        this.parent = parent;
    }

    @Override
    public void showWhile(final Runnable task) {
        try {
            showWhile(new Callable() {
                public Object call() throws Exception {
                    task.run();
                    return null;
                }
            });
        } catch (Exception e) {
            throw new RuntimeException("Should never happen.", e);
        }
    }

    @Override
    public <T> T showWhile(final Callable<T> task) throws Exception {
        start();

        final AtomicReference resultRef = new AtomicReference();
        display().asyncExec(new Runnable() {
            public void run() {
                try {
                    resultRef.set(task.call());
                } catch (Exception e) {
                    resultRef.set(e);
                } finally {
                    end();
                }
            }
        });
        if (resultRef.get() instanceof Exception) {
            throw (Exception) resultRef.get();
        } else {
            return (T) resultRef.get();
        }
    }

    protected Display display() {
        return BatikApplication.shellToParentOn().getDisplay();
    }

    protected void start() {
        assert parent == null : "Non null parents are not supported yet.";
        display().asyncExec(new Runnable() {
            public void run() {
                BatikApplication.shellToParentOn().setEnabled(false);
            }
        });
        //        while (display().readAndDispatch()) {
        //            log.info( "readAndDispatch() ..." );
        //        }
    }

    protected void end() {
        BatikApplication.shellToParentOn().setEnabled(true);
    }

}