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Parametric.java

/*************************************************************************
*                                                                        *
*  This source code file, and compiled classes derived from it, can      *
*  be used and distributed without restriction, including for commercial *
*  use.  (Attribution is not required but is appreciated.)               * 
*                                                                        *
*   David J. Eck                                                         *
*   Department of Mathematics and Computer Science                       *
*   Hobart and William Smith Colleges                                    *
*   Geneva, New York 14456,   USA                                        *
*   Email: eck@hws.edu          WWW: http://math.hws.edu/eck/            *
*                                                                        *
*************************************************************************/


// The ParametricCurve applet is a configurable applet that displays a parametric
// curve defined by two functions of a parameter t.  There can be a "Tracer" button
// on the applet.  When the user clicks this button, a crosshair is moved along
// the curve from beginning to end.

import java.awt.*;
import java.applet.Applet;
import java.util.StringTokenizer;
import java.util.Hashtable;
import edu.hws.jcm.draw.*;
import edu.hws.jcm.data.*;
import edu.hws.jcm.functions.*;
import edu.hws.jcm.awt.*;



public class Parametric extends GenericGraphApplet {

   // Declare some private variables that are created in one method in
   // this class and used in a second method.

   private Function xFunc,yFunc;    // The functions that are graphed.
   private ParametricCurve graph;   // The graph of the function.
   private Animator tracer;         // for tracing the curve by moving a crosshair along it
   private Crosshair crosshair;     // Crosshair used for tracing the graph
   private VariableInput tMin,tMax; // for inputting limits on t
   private VariableInput tIntervals; // for inutting the number of intervals into which the t-range is divided
   private ExpressionInput functionInput2;  // for inputting yFunc; xFunc is input in functionInput
   
   protected void setUpParameterDefaults() {
      parameterDefaults = new Hashtable();
      parameterDefaults.put("TwoLimitsColumns", "yes");
      parameterDefaults.put("Variable","t");
      parameterDefaults.put("XName","x");  // we need this so that xmin and xmax boxes are labeled correctly;
                                           // without it, the name would come from the variable name, t, instead of x
      parameterDefaults.put("FunctionLabel", "  " + getParameter("XName") + "(" + getParameter("Variable") + ") = ");
      parameterDefaults.put("FunctionLabel2", "  " + getParameter("YName","y") + "(" + getParameter("Variable") + ") = ");
   }

   protected void setUpCanvas() {  // Override this to add more stuff to the canvas.
   
      super.setUpCanvas();  // Do the common setup: Add the axes and

      // When setUpCanvas is called, the function inputs already exist, if they are
      // to be used, since they are created in setUpBopttomPanel(), which is called
      // before setUpCanvas().  If functionInput exists, add a graph of the functions
      // from functionInput and functionInput2 to the canvas.  If not, create a graph 
      // of the functions specified by the parameters named "Function" and "Function2".
      
      if (functionInput != null) {
         xFunc = functionInput.getFunction(xVar);
         yFunc = functionInput2.getFunction(xVar);
      }
      else {
         String xFuncDef = " cos(" + xVar.getName() + ") + cos(3*" + xVar.getName() + ")";
         String yFuncDef = " sin(4*" + xVar.getName() + ") - sin(2*" + xVar.getName() + ")";
         xFuncDef = getParameter("Function", xFuncDef);
         yFuncDef = getParameter("Function2", yFuncDef);
         Function f = new SimpleFunction( parser.parse(xFuncDef), xVar );
         xFunc = new WrapperFunction(f);
         f = new SimpleFunction( parser.parse(yFuncDef), xVar );
         yFunc = new WrapperFunction(f);
      }
      graph = new ParametricCurve(xFunc,yFunc);
      Color color = getColorParam("CurveColor");
      if (color != null)
         graph.setColor(color);
         
      // if inputs are desired to control the parameter on the curve, set them up here
         
      if  ("no".equalsIgnoreCase(getParameter("UseParamInputs","yes"))) {
         tMin = new VariableInput(xVar.getName() + "Start",getParameter("ParameterMin","-2"));
         tMax = new VariableInput(xVar.getName() + "End",getParameter("ParameterMax","2"));
         tIntervals = new VariableInput("Intervals", getParameter("Intervals","200"));
         tIntervals.setInputStyle(VariableInput.INTEGER);
         tIntervals.setMin(1);
         tIntervals.setMax(5000);
         tMin.setOnUserAction(mainController);
         tMax.setOnUserAction(mainController);
         tIntervals.setOnUserAction(mainController);
         graph.setTMin(tMin);
         graph.setTMax(tMax);
         graph.setIntervals(tIntervals);
         if (limitsPanel != null) {
               // componets will be added to limitsPanel in setUpLimitsPanel()
            mainController.add(tMin);  // This is not done automatically, since they are in a limits panel  
            mainController.add(tMax);
            mainController.add(tIntervals);
         }
         else {
            JCMPanel ap = new JCMPanel(9,0);
            ap.setBackground(getColorParam("PanelBackground", Color.lightGray));
            ap.add(new Label(tMin.getName()));
            ap.add(tMin);
            ap.add(new Label());
            ap.add(new Label(tMax.getName()));
            ap.add(tMax);
            ap.add(new Label());
            ap.add(new Label(tIntervals.getName()));
            ap.add(tIntervals);
            ap.add(new Label());
            mainPanel.add(ap,BorderLayout.EAST);
         }
      }
      else {
         try {
            graph.setTMin( new Constant((new Double(getParameter("ParameterMin","-2"))).doubleValue()) );
            graph.setTMax( new Constant((new Double(getParameter("ParameterMax","2"))).doubleValue()) );
            graph.setIntervals( new Constant((new Double(getParameter("Intervals","25"))).doubleValue()) );
         }
         catch (NumberFormatException e) {
         }
      }

      // If the applet is configured to have a tracer button, create it and add the crosshair to the canvas

      if (! "no".equalsIgnoreCase( getParameter("UseTracer","yes") ) ) {
         tracer = new Animator();
         tracer.setMin(graph.getTMin());
         tracer.setMax(graph.getTMax());
         tracer.setUndefinedWhenNotRunning(true);
         tracer.setStartButtonName("Trace Curve!");
         double[] d = getNumericParam("TracerIntervals");
         int ints;
         if (d == null || d.length != 1)
            ints = 100;
         else
            ints = (int)Math.round(d[0]);
         if (ints <= 0)
            tracer.setIntervals(graph.getIntervals());
         else
            tracer.setIntervals(ints);
         Variable v = tracer.getValueAsVariable();
         crosshair = new Crosshair( new ValueMath(xFunc,v), new ValueMath(yFunc,v) );
         crosshair.setLineWidth(3);
         crosshair.setColor(getColorParam("CrosshairColor",Color.gray));
         canvas.add(crosshair);
            
         if (inputPanel != null) {
            inputPanel.add(tracer,BorderLayout.WEST);
         }
         else if (limitsPanel == null) {
            Panel p = new Panel();
            p.add(tracer);
            mainPanel.add(p,BorderLayout.SOUTH);
         }
         // if inputPanel is null but limitsPanel is not null, the tracer will be
         //    added to the limit control panel in setUpLimitsPanel()
      }

      canvas.add(graph);  // Finally, add the graph to the canvas.

   } // end setUpCanvas()
   

   protected void setUpLimitsPanel() {
      super.setUpLimitsPanel();
      if (limitsPanel != null && tMin != null) {  // add parameter inputs to limits panel
          limitsPanel.addComponentPair(tMin,tMax);
          limitsPanel.addComponent(tIntervals);
      }
      if (inputPanel == null && tracer != null && limitsPanel != null)  {
          limitsPanel.addComponent(tracer);
      }
   }
 
   
   protected void setUpBottomPanel() { // override this to make a panel containing inputs for two functions
      if ( ! "no".equalsIgnoreCase(getParameter("UseFunctionInput", "yes")) ) {
      
         inputPanel = new JCMPanel();
         inputPanel.setBackground( getColorParam("PanelBackground", Color.lightGray) );
         Panel in = new JCMPanel(2,1);
         inputPanel.add(in,BorderLayout.CENTER);
       
         if ( ! "no".equalsIgnoreCase(getParameter("UseComputeButton", "yes")) ) {
            String cname = getParameter("ComputeButtonName", "New Functions");
            computeButton = new Button(cname);
            inputPanel.add(computeButton, BorderLayout.EAST); 
            computeButton.addActionListener(this);
         }

         String varName = getParameter("Variable");
         String def = getParameter("Function");
         if (def == null)
            def = "cos(" + varName + ") + cos(3*" + varName + ")";
         functionInput = new ExpressionInput(def,parser);
         String label = getParameter("FunctionLabel");
         if ("none".equalsIgnoreCase(label))
            in.add(functionInput);
         else {
            Panel p = new JCMPanel();
            p.add(functionInput,BorderLayout.CENTER);
            p.add( new Label(label), BorderLayout.WEST );
            in.add(p);
         }
         
         def = getParameter("Function2");
         if (def == null)
            def = "sin(4*" + varName + ") - sin(2*" + varName + ")";
         functionInput2 = new ExpressionInput(def,parser);
         label = getParameter("FunctionLabel2");
         if ("none".equalsIgnoreCase(label))
            in.add(functionInput2);
         else {
            Panel p = new JCMPanel();
            p.add(functionInput2,BorderLayout.CENTER);
            p.add( new Label(label), BorderLayout.WEST );
            in.add(p);
         }
         
         mainPanel.add(inputPanel, BorderLayout.SOUTH);
         functionInput.setOnUserAction(mainController);
         functionInput2.setOnUserAction(mainController);
      }
   }
      

   protected void setUpMainPanel() { // Override to set up controller for tracer, if there is one
   
      super.setUpMainPanel(); // Do the common setup

      if ( tracer == null ) {
         return;  // If the applet is not configured to use a trace button, there is nothing to do.
      }

      Controller traceController = new Controller();  // A controler that will only recompute the crosshair position
      traceController.add(tracer);
      traceController.add(crosshair);
      tracer.setOnChange(traceController);

   } // end setUpMainPanel()
   
   protected void doLoadExample(String example) {
         // This method is called when the user loads an example from the 
         // example menu (if there is one).  It overrides an empty method
         // in GenericGraphApplet.
         //   For the Parametric applet, the example string should contain
         // two expression that defines the curve to be graphed, separated 
         // by a semicolon.  This can optionally
         // be followed by another semicolon and a list of four to seven numbers.
         // The first four numbers give the x- and y-limits to be used for the
         // example.  If they are not present, then -5,5,-5,5 is used.  The
         // next three numbers specify the minimum value for the parameter, the
         // maximum value, and the number of intervals into which the range of
         // parameter values is divided.
         
      if (tracer != null)
         tracer.stop();
         
      int pos = example.indexOf(";");
      if (pos == -1)
         return; // illegal example -- must have two functions
      String example2 = example.substring(pos+1);
      example = example.substring(0,pos);
      pos = example2.indexOf(";");   
      
         
      double[] limits = { -5,5,-5,5 }; // x- and y-limits to use

      if (pos > 0) { 
               // Get limits from example2 text.
         String nums = example2.substring(pos+1);
         example2 = example2.substring(0,pos);
         StringTokenizer toks = new StringTokenizer(nums, " ,");
         if (toks.countTokens() >= 4) {
            for (int i = 0; i < 4; i++) {
               try {
                   Double d = new Double(toks.nextToken());
                   limits[i] = d.doubleValue();
               }
               catch (NumberFormatException e) {
               }
            }
         }
         if (toks.hasMoreTokens()) {
            try {
               double d = (new Double(toks.nextToken())).doubleValue();
               if (tMin == null) {
                  graph.setTMin(new Constant(d));
                  if (tracer != null)
                     tracer.setMin(d);
               }
               else
                  tMin.setVal(d);
            }
            catch (NumberFormatException e) {
            }
         }
         if (toks.hasMoreTokens()) {
            try {
               double d = (new Double(toks.nextToken())).doubleValue();
               if (tMax == null) {
                  graph.setTMax(new Constant(d));
                  if (tracer != null)
                     tracer.setMax(d);
               }
               else
                  tMax.setVal(d);
            }
            catch (NumberFormatException e) {
            }
         }
         if (toks.hasMoreTokens()) {
            try {
               int d = (int)Math.round((new Double(toks.nextToken())).doubleValue());
               if (tIntervals == null) {
                  if (tracer != null && tracer.getIntervals() == graph.getIntervals())
                     tracer.setIntervals(d);
                  graph.setIntervals(new Constant(d));
               }
               else
                  tIntervals.setVal(d);
            }
            catch (NumberFormatException e) {
            }
         }
      }
      
      // Set up the example data and recompute everything.

      if (functionInput != null) {
            // If there is a function input box, put the example text in it.
         functionInput.setText(example);
         functionInput2.setText(example2);
      }
      else { 
           // If there is no user input, set the function in the graph directly.
         try {
            Function f = new SimpleFunction( parser.parse(example), xVar );
            ((WrapperFunction)xFunc).setFunction(f);
            Function g = new SimpleFunction( parser.parse(example2), xVar );
            ((WrapperFunction)yFunc).setFunction(g);
         }
         catch (ParseError e) {  
             // There should't be parse error's in the Web-page
             // author's examples!  If there are, the function
             // just won't change.
         }
      }
      CoordinateRect coords = canvas.getCoordinateRect(0);
      coords.setLimits(limits);
      coords.setRestoreBuffer();
      mainController.compute();
      
   } // end doLoadExample()
   

   public void stop() {  // stop animator when applet is stopped
      if (tracer != null)
         tracer.stop();
      super.stop();
   }
 



} // end class Parametric

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