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TableFunctionInput.java

/*************************************************************************
*                                                                        *
*   1) This source code file, in unmodified form, and compiled classes   *
*      derived from it can be used and distributed without restriction,  *
*      including for commercial use.  (Attribution is not required       *
*      but is appreciated.)                                              *
*                                                                        *
*    2) Modified versions of this file can be made and distributed       *
*       provided:  the modified versions are put into a Java package     *
*       different from the original package, edu.hws;  modified          *
*       versions are distributed under the same terms as the original;   *
*       and the modifications are documented in comments.  (Modification *
*       here does not include simply making subclasses that belong to    *
*       a package other than edu.hws, which can be done without any      *
*       restriction)                                                     *
*                                                                        *
*   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/            *
*                                                                        *
*************************************************************************/


package edu.hws.jcm.functions;

import java.awt.*;
import java.awt.event.*;
import edu.hws.jcm.data.*;
import edu.hws.jcm.awt.*;
import edu.hws.jcm.draw.*;


/**
 * A TableInputFunction is a Panel that can be used to define a TableFunction
 * or to edit an existing TableFunction.  To fetch the function currently
 * displayed in the panel, call copyOfCurrentFunction().  To edit a function,
 * call startEdit() to install the function.  Then call cancelEdit() or
 * finishEdit() to finish the editing.  The panel displays both the graph
 * of the function and a list of points that define the function.  The user
 * can drag the points on the graph up and down to change the y-values.
 * Points can be added or modified by typing in their x- and y-coordinates.
 * A point can be deleted by clicking it in the list of points and then
 * clicking on the button labeled "Delete Point".
 */
00047 public class TableFunctionInput extends Panel 
         implements ItemListener, ActionListener, MouseListener, MouseMotionListener {
 
   private VariableInput xInput, yInput;  // Components of the GUI.
   private DisplayCanvas canvas;
   private List pointList;
   private Button clearButton, deleteButton, addButton;
   private Checkbox[] styleCheckbox = new Checkbox[5];
   private CheckboxGroup styleGroup;
   
   private Controller onChange; // If non-null, the compute() method of the controller
                                // is called when the user edits a point.
   
   private TableFunction function;      // The function displayed.
   private TableFunction editFunction;  // If non-null, the function passed to startEdit.


   /**
    * Create a TableFunctionInput panel.  Initially, the function in the
    * panel has no points and so is undefined everywhere.  The panel needs
    * to be fairly large!
    */
00069    public TableFunctionInput() {
   
      xInput = new VariableInput();
      xInput.addActionListener(this);
      yInput = new VariableInput();
      yInput.addActionListener(this);
      
      pointList = new List();
      pointList.setBackground(Color.white);
      pointList.setFont(new Font("Monospaced",Font.PLAIN,12));
      pointList.addItemListener(this);
      
      clearButton = new Button("Remove All Points");
      clearButton.addActionListener(this);
      deleteButton = new Button("Delete Point");
      deleteButton.setEnabled(false);
      deleteButton.addActionListener(this);
      addButton = new Button("Add/Modify Point");
      addButton.addActionListener(this);
      
      styleGroup = new CheckboxGroup();
      styleCheckbox[0] = new Checkbox("Smooth", true, styleGroup);
      styleCheckbox[1] = new Checkbox("Piecewise Linear", false, styleGroup);
      styleCheckbox[2] = new Checkbox("Step (nearest value)", false, styleGroup);
      styleCheckbox[3] = new Checkbox("Step (value from left)", false, styleGroup);
      styleCheckbox[4] = new Checkbox("Step (value from right)", false, styleGroup);
      for (int i = 0; i < 5; i++)   
         styleCheckbox[i].addItemListener(this);
      
      canvas = new DisplayCanvas( new CoordinateRect(-1,1,-1,1) );
      canvas.add(new Axes());
      canvas.addMouseListener(this);
      canvas.addMouseMotionListener(this);
      
      function = new TableFunction();
      canvas.add(new Draw());
      
      Font labelFont = new Font("Serif", Font.BOLD, 12);
      Label lab1 = new Label("Input Area");
      lab1.setForeground(Color.red);
      lab1.setFont(labelFont);
      Label lab2 = new Label("Type of Function", Label.CENTER);
      lab2.setForeground(Color.red);
      lab2.setFont(labelFont);
      Label lab3 = new Label("Table of Values", Label.CENTER);
      lab3.setForeground(Color.red);
      lab3.setFont(labelFont);
      
      Panel topLeft = new Panel();
      topLeft.setLayout(new FlowLayout(FlowLayout.CENTER, 10000,3));
      Panel topRight = new Panel();
      topRight.setLayout(new GridLayout(6,1,3,3));
      Panel bottomLeft = new Panel();
      bottomLeft.setLayout(new BorderLayout());
      Panel top = new Panel();
      top.setLayout(new BorderLayout(3,3));
      top.add(topLeft,BorderLayout.CENTER);
      top.add(topRight,BorderLayout.EAST);
      setLayout(new BorderLayout(3,3));
      add(top,BorderLayout.NORTH);
      add(bottomLeft, BorderLayout.WEST);
      add(canvas, BorderLayout.CENTER);
      setBackground(Color.darkGray);
      topLeft.setBackground(Color.lightGray);
      topRight.setBackground(Color.lightGray);
      bottomLeft.setBackground(Color.lightGray);
      
      Panel inputBar = new Panel();
      inputBar.add(new Label("x = "));
      inputBar.add(xInput);
      inputBar.add(new Label(" y = "));
      inputBar.add(yInput);
      
      Panel buttonBar = new Panel();
      buttonBar.setLayout(new GridLayout(1,2,3,3));
      buttonBar.add(deleteButton);
      buttonBar.add(clearButton);
      
      topLeft.add(lab1);
      topLeft.add(inputBar);
      topLeft.add(addButton);
      topLeft.add(new Label("(Press RETURN in X to move to Y)"));
      topLeft.add(new Label("(Press RETURN in Y to add/modify point)"));

      topRight.add(lab2);
      for (int i = 0; i < 5; i++)   
         topRight.add(styleCheckbox[i]);
         
      bottomLeft.add(pointList, BorderLayout.CENTER);
      bottomLeft.add(lab3, BorderLayout.NORTH);
      bottomLeft.add(buttonBar, BorderLayout.SOUTH);
      
   }  // end constructor
   
   //------------------- Methods for modifying an existing function --------------
   
   /**
    * Install a function to be edited.  The data from the function is
    * copied into the panel, and a pointer to the function is retained.
    * Note that the function itself is not changed by any editing that 
    * the user does.  To commit the changes made by the user to the
    * actual function, you must call finishEdit().  If f is null,
    * the effect is to start with a new, empty function.
    */
00173    public void startEdit(TableFunction f) {
      editFunction = f;
      revertEditFunction(); // Installs data from function.
   }
   
   /**
    * If a function has been specified using startEdit(), and neither
    * finishEdit() nor cancelEdit have been called, then this method
    * will discard the current data in and replace it with data from
    * the edit function.  If there is no edit function, then the data
    * is simply discarded.  (That is, the data reverts to an empty point list.)
    */
00185    public void revertEditFunction() {
      if (editFunction == null) {
         clearAllPoints();
         return;
      }
      function.copyDataFrom(editFunction);
      pointList.removeAll();
      int pointCt = function.getPointCount();
      for (int i = 0; i < pointCt; i++)
         pointList.add(makePointString(function.getX(i),function.getY(i)));
      styleGroup.setSelectedCheckbox(styleCheckbox[function.getStyle()]);
      checkCanvas();
      if (onChange != null)
         onChange.compute();
   }
   
   /**
    * If an edit function has been specified (by startEdit()), this function copies the
    * data form the TableFunctionInput into that function, and returns a
    * pointer to that function.  This ends the edit session, and the internally stored
    * pointer to the edit function is discarded.  If no edit function has been specified
    * then a new TableFunction is created with the data from the panel, and a 
    * pointer to the new function is returned.  This does not clear the data
    * in the TableFunctionInput panel.
    */ 
00210    public TableFunction finishEdit() {
      TableFunction func;
      if (editFunction == null)
         func = copyOfCurrentFunction();
      else {
         editFunction.copyDataFrom(function);
         func = editFunction;
         editFunction = null;
      }
      return func;
   }
   
   /**
    * Discards the internal pointer to the edit function (specified by startEdit()),
    * if any.   This does not clear the data in the TableFunctionInput panel.
    */
00226    public void cancelEdit() {
      editFunction = null;
   }

   /**
    * Create a new TableFunction containing the data that is currently
    * in the TableFunctionInput panel, and return a pointer to that new function.
    */   
00234    public TableFunction copyOfCurrentFunction() {
      TableFunction copy =  new TableFunction();
      copy.copyDataFrom(function);
      copy.setName(function.getName());
      return copy;
   }
   
   /**
    * Specify a controller whose compute() method will be called whenever
    * the user edits the data in this TableFunctionInput panel.  (Note that
    * when the user edits the function by dragging a point, the Controller
    * is only called once at the end of the drag.)  If the specified 
    * Controller is null, then no notification takes place.
    */
00248    public void setOnChange(Controller c) {
      onChange = c;
   }
   
   /**
    * Get the Controller that is notified when the user edits the data
    * in this panel.  The return value can be null (the default), indicating
    * that no notification takes place.
    */ 
00257    public Controller getOnChange() {
      return onChange;
   }
   
   private void deletePoint() {
         // delete point selected in the point list, if any
      int index = pointList.getSelectedIndex();
      if (index >= 0) {
         pointList.remove(index);
         function.removePointAt(index);
         checkCanvas();
         if (onChange != null)
            onChange.compute();
      }
      deleteButton.setEnabled(false);
   }
   
   private void clearAllPoints() {
          // remove all points, leaving an empty point list
       function.removeAllPoints();
       pointList.removeAll();
       deleteButton.setEnabled(false);
       if (onChange != null)
          onChange.compute();
       checkCanvas();
   }
   
   private void addPoint() {
         // add the point whose coords are specified in the x and y input boxes;
         // if the x-value already exits, then the corresponding y-value is changed.
      double x,y;
      try {
          xInput.checkInput();
          x = xInput.getVal();
      }
      catch (JCMError e) {
         canvas.setErrorMessage(null,"The input for x does is not a legal real number.");
         xInput.requestFocus();
         xInput.selectAll();
         return;
      }
      try {
          yInput.checkInput();
          y = yInput.getVal();
      }
      catch (JCMError e) {
         canvas.setErrorMessage(null,"The input for y does is not a legal real number.");
         yInput.requestFocus();
         yInput.selectAll();
         return;
      }
      String str = makePointString(x,y);
      int index = function.findPoint(x);
      if (index >= 0 && y == function.getY(index)) {
         xInput.requestFocus();
         xInput.selectAll();
         return;
      }
      int newindex = function.addPoint(x,y);
      if (index >= 0)
          pointList.replaceItem(str,index);
      else
         pointList.addItem(str,newindex);
      deleteButton.setEnabled(pointList.getSelectedIndex() != -1);
      checkCanvas();
      if (onChange != null)
         onChange.compute();
      xInput.requestFocus();
      xInput.selectAll();
   }
   
   private String makePointString(double x, double y) {
         // Make a string representing (x,y), using exactly 11 spaces for each number.
      String X = NumUtils.realToString(x);
      String Y = NumUtils.realToString(y);
      if (X.length() < 11)
         X = "            ".substring(0,11 - X.length()) + X;
      if (Y.length() < 11)
         Y = "            ".substring(0,11 - Y.length()) + Y;
      return X + " " + Y;
   }
   
   private void selectPoint() {
         // React when user selects a point in the list of points.
      int index = pointList.getSelectedIndex();
      if (index >= 0) {
         xInput.setVal(function.getX(index));
         yInput.setVal(function.getY(index));
         yInput.requestFocus();
         yInput.selectAll();
      }
      deleteButton.setEnabled(index >= 0);
   }
   
   private void changeStyle() {
         // React when user changes style of function.
      int newstyle = 0;
      Checkbox selected = styleGroup.getSelectedCheckbox();
      for (int i = 1; i < 5; i++)
         if (selected == styleCheckbox[i])
            newstyle = i;
      if (function.getStyle() == newstyle)
         return;
      function.setStyle(newstyle);
      canvas.doRedraw();
      if (onChange != null)
         onChange.compute();
   }
   
   private void checkCanvas() {
          // Adjust limits on canvas, if necessary, and redraw it.
       int ct = function.getPointCount();
       double newXmin = -1, newXmax = 1, newYmin = -1, newYmax = 1;
       if (ct > 0) {
          if (ct == 1) {
             newXmin = function.getX(0);
             if (Math.abs(newXmin) < 10000) {
                newXmax = newXmin + 1;
                newXmin -= 1;
             }
             else {
                newXmax = newXmin - Math.abs(newXmin)/10;
                newXmin -= Math.abs(newXmin)/10;
             }
          }
          else {
             newXmin = function.getX(0);
             newXmax = function.getX(ct - 1);
          }
          newYmin = function.getY(0);
          newYmax = newYmin;
          for (int i = 1; i < ct; i++) {
             double y = function.getY(i);
             if (y < newYmin)
                newYmin = y;
             else if (y > newYmax)
                newYmax = y;
          } 
          double size = Math.abs(newYmin - newYmax);
          if (size < 1e-10 && Math.abs(newYmin) < 10000 && Math.abs(newYmax) < 10000) {
              newYmax += 1;
              newYmin -= 1;
          }
          else {
             newYmax += size*0.15;
             newYmin -= size*0.15;
          }
       }
       CoordinateRect coords = canvas.getCoordinateRect(0);
       double curSize = Math.abs(coords.getYmin() - coords.getYmax());
       double newSize = Math.abs(newYmax - newYmin);
       if (newXmax != coords.getXmax() || newXmin != coords.getXmin()
             || newSize > 1.3*curSize || newSize < 0.5*curSize
             || newYmax > coords.getYmax() - 0.1*curSize
             || newYmin < coords.getYmin() + 0.1*curSize)
          coords.setLimits(newXmin,newXmax,newYmin,newYmax);
       canvas.doRedraw();
   }
   
   /**
    * Leave a 3-pixel gap around the edges of the panel.  Not meant to be called directly.
    */
00419    public Insets getInsets() {
      return new Insets(3,3,3,3);
   }
   
   /**
    * React when user clicks one of the buttons or presses return in one
    * of the input boxes.  Not meant to be called directly.
    */
00427    public void actionPerformed(ActionEvent evt) {
      Object source = evt.getSource();
      if (source == deleteButton)
         deletePoint();
      else if (source == clearButton)
         clearAllPoints();
      else if (source == xInput) {
         yInput.requestFocus();
         yInput.selectAll();
      }
      else
         addPoint();
   }
   
   /**
    * React when user clicks on a point in the list of points or clicks one
    * of the radio buttons for specifying the style of the function.
    * Not meant to be called directly.
    */
00446    public void itemStateChanged(ItemEvent evt) {
      if (evt.getSource() == pointList)
         selectPoint();
      else
         changeStyle();
   }
   
   //-------------------- Dragging --------------------------
   
   private int dragPoint = -1;  // -1 if no point is being dragged;
                                // Otherwise, the index of the point being dragged.
                                
   private int startX, startY;  // Point where mouse was clicked at start of drag.
   
   private int prevY;  // Previous position of mouse during dragging.

   private boolean moved;  // Becomes true once the clicked point has actually
                           // been dragged a bit.  If the mouse is released before
                           // the point is moved at least 3 pixels, then the associated 
                           // y-value is not changed.
   
   /**
    * Method required by the MouseListener interface.  Defined here to
    * support dragging of points on the function's graph.   Not meant to be called directly.
    */
00471    public void mousePressed(MouseEvent evt) {
      dragPoint = -1;
      moved = false;
      int ct = function.getPointCount();
      CoordinateRect coords = canvas.getCoordinateRect(0);
      for (int i = 0; i < ct; i++) {
         int x = coords.xToPixel(function.getX(i));
         int y = coords.yToPixel(function.getY(i));
         if (evt.getX() >= x-3 && evt.getX() <= x+3 && evt.getY() >= y-3 && evt.getY() <= y+3) {
            startX = evt.getX();
            prevY = startY = evt.getY();
            pointList.deselect(pointList.getSelectedIndex());
            pointList.select(i);
            selectPoint();
            dragPoint = i;
            return;
         }
      }
   }
   
   /**
    * Method required by the MouseListener interface.  Defined here to
    * support dragging of points on the function's graph.   Not meant to be called directly.
    */
00495    public void mouseReleased(MouseEvent evt) {
      if (dragPoint == -1)
         return;
      if (!moved) {
         dragPoint = -1;
         return;
      }
      mouseDragged(evt);
      pointList.replaceItem(makePointString(function.getX(dragPoint),function.getY(dragPoint)), dragPoint);
      pointList.select(dragPoint);
      dragPoint = -1;
      if (onChange != null)
         onChange.compute();
   }
   
   /**
    * Method required by the MouseListener interface.  Defined here to
    * support dragging of points on the function's graph.   Not meant to be called directly.
    */
00514    public void mouseDragged(MouseEvent evt) {
      if (dragPoint == -1 || prevY == evt.getY())
         return;
      if (!moved && Math.abs(evt.getY() - startY) < 3)
         return;
      moved = true;
      int y = evt.getY();
      CoordinateRect coords = canvas.getCoordinateRect(0);
      if (y < coords.getTop() + 4)
         y = coords.getTop() + 4;
      else if (y > coords.getTop() + coords.getHeight() - 4)
         y = coords.getTop() + coords.getHeight() - 4;
      if (Math.abs(evt.getX() - startX) > 72)
         y = startY;
      if (y == prevY)
         return;
      prevY = y;
      function.setY(dragPoint, coords.pixelToY(prevY));
      yInput.setVal(function.getY(dragPoint));
      canvas.doRedraw();
   }
   
   /**
    * Empty method, required by the MouseListener interface.
    */
00539    public void mouseClicked(MouseEvent evt) { }

   /**
    * Empty method, required by the MouseMotionListener interface.
    */
00544    public void mouseEntered(MouseEvent evt) { }

   /**
    * Empty method, required by the MouseMotionListener interface.
    */
00549    public void mouseExited(MouseEvent evt) { }

   /**
    * Empty method, required by the MouseMotionListener interface.
    */
00554    public void mouseMoved(MouseEvent evt) { }
   
   
   
   //--------------------------------------------------------
   
   private class Draw extends Drawable{
         // An object of this nested class is added to the canvas
         // of the TableFunctionInput panel.  It is responsible for
         // drawing the function.
   
      public void draw(Graphics g, boolean coordsChanged) {
         int ct = function.getPointCount();
         if (ct == 0)
            return;
         g.setColor(Color.magenta);   
         int xInt,yInt, aInt, bInt;
         double x,y, a,b;
         switch (function.getStyle()) {
            case TableFunction.SMOOTH: {
               if (ct > 1) { try {
                  x = function.getX(0);
                  y = function.getVal(x);
                  xInt = coords.xToPixel(x);
                  yInt = coords.yToPixel(y);
                  int limit = coords.xToPixel(function.getX(ct-1));
                  aInt = xInt;
                  while (aInt < limit) {
                     aInt += 3;
                     if (aInt > limit)
                        aInt = limit;
                     a = coords.pixelToX(aInt);
                     b = function.getVal(a);
                     bInt = coords.yToPixel(b);
                     g.drawLine(xInt,yInt,aInt,bInt);
                     xInt = aInt;
                     yInt = bInt;
                  } } catch (Exception e) { e.printStackTrace(); }
               }
               break;
            }
            case TableFunction. PIECEWISE_LINEAR: {
               x = function.getX(0);
               xInt = coords.xToPixel(x);
               y = function.getY(0);
               yInt = coords.yToPixel(y);
               for (int i = 1; i < ct; i++) {
                  a = function.getX(i);
                  aInt = coords.xToPixel(a);
                  b = function.getY(i);
                  bInt = coords.yToPixel(b);
                  g.drawLine(xInt,yInt,aInt,bInt);
                  xInt = aInt;
                  yInt = bInt;
               }
               break;
            }
            case TableFunction.STEP: {
               x = function.getX(0);
               xInt = coords.xToPixel(x);
               for (int i = 0; i < ct; i++) {
                  if (i < ct - 1) {
                     double nextX = function.getX(i+1);
                     a = (x + nextX)/2;
                     x = nextX;
                  }
                  else
                     a = x;
                  aInt = coords.xToPixel(a);
                  y = function.getY(i);
                  yInt = coords.yToPixel(y);
                  g.drawLine(xInt,yInt,aInt,yInt);
                  xInt = aInt;
               }
               break;
            }
            case TableFunction.STEP_LEFT: {
               x = function.getX(0);
               xInt = coords.xToPixel(x);
               for (int i = 1; i < ct; i++) {
                  a = function.getX(i);
                  aInt = coords.xToPixel(a);
                  y = function.getY(i-1);
                  yInt = coords.yToPixel(y);
                  g.drawLine(xInt,yInt,aInt,yInt);
                  xInt = aInt;
               }
               break;
            }
            case TableFunction.STEP_RIGHT: {
               x = function.getX(0);
               xInt = coords.xToPixel(x);
               for (int i = 1; i < ct; i++) {
                  a = function.getX(i);
                  aInt = coords.xToPixel(a);
                  y = function.getY(i);
                  yInt = coords.yToPixel(y);
                  g.drawLine(xInt,yInt,aInt,yInt);
                  xInt = aInt;
               }
               break;
            }
         }
         for (int i = 0; i < ct; i++) {
            x = function.getX(i);
            y = function.getY(i);
            xInt = coords.xToPixel(x);
            yInt = coords.yToPixel(y);
            g.fillOval(xInt-2,yInt-2,5,5);  
         }
      }
   
   }

}

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