PTOLEMY II - CiteSeerX

Custom Applets
8.3.5 Using Model Parameters
Typically, a model has a set of parameters that you wish for the user to be able to control in the
applet. Suppose for example that in the above applet you wish for the user to be able to control the stop
time of the director and the period of the clock actor. You can modify the Java code in figure 8.3 as
shown in figure 8.8. This code uses the Parameter class to define two top-level parameters. The following
lines create the top-level parameters:
Parameter stopTime = new Parameter(this, "stopTime");
Parameter clockPeriod = new Parameter(this, "clockPeriod");
The default values of these two parameters are set by the following lines:
stopTime.setExpression("10.0");
clockPeriod.setExpression("2.0");
package doc.tutorial;
import ptolemy.actor.TypedCompositeActor;
import ptolemy.actor.gui.PtolemyApplet;
import ptolemy.actor.lib.Clock;
import ptolemy.actor.lib.gui.TimedPlotter;
import ptolemy.data.expr.Parameter;
import ptolemy.domains.de.kernel.DEDirector;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;
import ptolemy.kernel.util.Workspace;
public class TutorialApplet3 extends TypedCompositeActor {
public TutorialApplet3(Workspace workspace)
throws IllegalActionException, NameDuplicationException {
super(workspace);
}
}
// Create model parameters
Parameter stopTime = new Parameter(this, "stopTime");
Parameter clockPeriod = new Parameter(this, "clockPeriod");
// Give the model parameters default values.
stopTime.setExpression("10.0");
clockPeriod.setExpression("2.0");
// Create the director
DEDirector director = new DEDirector(this, "director");
setDirector(director);
// Create two actors.
Clock clock = new Clock(this,"clock");
TimedPlotter plotter = new TimedPlotter(this,"plotter");
// Set the user controlled parameters.
director.stopTime.setExpression("stopTime");
clock.period.setExpression("clockPeriod");
// Connect the actors.
connect(clock.output, plotter.input);
FIGURE 8.8. Code that adds model parameters control to the applet. This code can be found in $PTII/doc/
tutorial/TutorialApplet3.java.
Heterogeneous Concurrent Modeling and Design 8-241