AbstractStepGeneratorPage.java

/*
 * This file is part of the OpenSCADA project
 * Copyright (C) 2006-2010 TH4 SYSTEMS GmbH (http://th4-systems.com)
 *
 * OpenSCADA is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 3
 * only, as published by the Free Software Foundation.
 *
 * OpenSCADA 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 version 3 for more details
 * (a copy is included in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3 along with OpenSCADA. If not, see
 * <http://opensource.org/licenses/lgpl-3.0.html> for a copy of the LGPLv3 License.
 */

package org.openscada.da.client.signalgenerator.page;

import org.eclipse.core.runtime.Status;
import org.eclipse.swt.widgets.Display;
import org.openscada.da.client.signalgenerator.Activator;
import org.openscada.da.client.signalgenerator.SimulationTarget;

public abstract class AbstractStepGeneratorPage implements GeneratorPage
{

    private long lastTimestamp;

    protected Display display;

    private volatile boolean running;

    private final long period = 250;

    private final int tickDelay = 100;

    protected SimulationTarget target;

    protected abstract void step ();

    public void dispose ()
    {
        stop ();
    }

    public void setDisplay ( final Display display )
    {
        this.display = display;
    }

    public void start ()
    {
        this.lastTimestamp = 0;
        this.running = true;
        setTimer ();
    }

    private void setTimer ()
    {
        this.display.timerExec ( this.tickDelay, new Runnable () {
            public void run ()
            {
                AbstractStepGeneratorPage.this.tick ();
            }
        } );
    }

    public void stop ()
    {
        this.running = false;
    }

    private void tick ()
    {
        if ( !this.running )
        {
            return;
        }

        final long now = System.currentTimeMillis ();
        try
        {
            if ( now - this.lastTimestamp < this.period )
            {
                step ();
            }
        }
        catch ( final Throwable e )
        {
            Activator.getDefault ().getLog ().log ( new Status ( Status.ERROR, Activator.PLUGIN_ID, "Failed to step", e ) ); //$NON-NLS-1$
            e.printStackTrace ();
        }
        finally
        {
            this.lastTimestamp = now;
            setTimer ();
        }

    }

    public void setTarget ( final SimulationTarget target )
    {
        this.target = target;
    }

}