gda.device.scannable.TwoJawSlitGap.java Source code

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Here is the source code for gda.device.scannable.TwoJawSlitGap.java

Source

/*-
 * Copyright  2009 Diamond Light Source Ltd.
 *
 * This file is part of GDA.
 *
 * GDA is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License version 3 as published by the Free
 * Software Foundation.
 *
 * GDA 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along
 * with GDA. If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * 
 */
package gda.device.scannable;

import gda.device.DeviceException;
import gda.util.QuantityFactory;
import gda.util.persistence.LocalParameters;

import org.apache.commons.configuration.FileConfiguration;
import org.jscience.physics.quantities.Quantity;
import org.jscience.physics.units.Unit;

/**
 * The gap of a two jaw slit.
 * <p>
 * Based on TwoJawSlitPosition.
 */
public class TwoJawSlitGap extends TwoJawSlitPosition {

    private String xmlparametersfilename = null;

    @Override
    protected double[] getLimits(Quantity firstJawMin, Quantity firstJawMax, Quantity secondJawMin,
            Quantity secondJawMax) {
        Unit<?> units = unitsComponent.getUserUnit();
        double minimum = QuantityFactory.createFromObject(firstJawMin.minus(secondJawMax), units).getAmount();
        double maximum = QuantityFactory.createFromObject(firstJawMax.minus(secondJawMin), units).getAmount();
        return new double[] { minimum > 0. ? minimum : 0., maximum };
    }

    @Override
    public Object rawGetPosition() throws DeviceException {

        // return position as a double
        return unitsComponent.convertObjectToUserUnitsAssumeUserUnits(getCurrentGap());
    }

    /**
     * This string is the name of the xml parameters file which is used to store the beam centre used by these slits.
     * If this value is set to a non-null value then the behaviour of this scannable is changed to move the gap based
     * on the beam centre in this xml file rather than use the current beam centre. This is useful for motors which 
     * drift or frequently fail. 
     * 
     * @param xmlparametersfilename
     *            The xmlparametersfilename to set.
     */
    public void setXmlparametersfilename(String xmlparametersfilename) {
        this.xmlparametersfilename = xmlparametersfilename;
    }

    /**
     * @return Returns the xmlparametersfilename.
     */
    public String getXmlparametersfilename() {
        return xmlparametersfilename;
    }

    @Override
    protected Quantity[] calculateTargets(Object position) throws DeviceException {
        // convert what is supplied to Quantity in user units
        Quantity target = QuantityFactory.createFromObject(position, this.unitsComponent.getUserUnit());
        Quantity[] targets = new Quantity[2];

        if (xmlparametersfilename != null) {
            // perform calculation based on the beam centre in the xml file
            try {
                //first check the file exists then load using the New version to ensure any changes outside the VM are picked up
                LocalParameters.getXMLConfiguration(xmlparametersfilename, false);
                FileConfiguration config = LocalParameters.getNewXMLConfiguration(xmlparametersfilename);
                double xmlCentreDbl = config.getDouble(getName());
                Quantity xmlCentre = QuantityFactory.createFromObject(xmlCentreDbl,
                        this.unitsComponent.getUserUnit());
                targets[0] = xmlCentre.plus(target.divide(2.0));
                targets[1] = xmlCentre.minus(target.divide(2.0));
            } catch (Exception e) {
                throw new DeviceException(e.getMessage(), e);
            }
            // 
        } else {
            // perform the calculation based on the current beam centre i.e. current motor positions
            Quantity currentGap = getCurrentGap();
            Quantity delta = target.minus(currentGap).divide(2);
            Quantity firstJawPosition = QuantityFactory.createFromObject(firstJaw.getPosition(),
                    QuantityFactory.createUnitFromString(this.firstJaw.getUserUnits()));
            Quantity secondJawPosition = QuantityFactory.createFromObject(secondJaw.getPosition(),
                    QuantityFactory.createUnitFromString(this.firstJaw.getUserUnits()));

            targets[0] = firstJawPosition.plus(delta);
            targets[1] = secondJawPosition.minus(delta);
        }
        return targets;
    }
}