SimplePlot
/* My first graphing applet. */
/* Need to: put in a status line.
see why it doesn't use the full range of ymin to ymax
when I change functions.
put tick marks into a function.
*/
import java.awt.*;
import java.util.*;
import java.applet.Applet;
public class SimplePlot extends Applet {
TextField fromFld, toFld;
String MyText;
Label label, toLabel, fromLabel, statusLabel;
PlotCanvas canvas;
public int i;
Button redb, blueb, domainChangeb;
Color color;
Panel panel1, panel2, bottomPanel, statusPanel, xdomainPanel;
Choice fnChoice;
float beginXmin = -100, beginXmax = 100;
public void init() {
setLayout(new BorderLayout(5,5));
panel1 = new Panel();
label = new Label("Plotting a Function");
panel1.add(label);
add("North", panel1);
panel2 = new Panel();
panel2.setLayout(new GridLayout(0,1,5,5));
panel2.add(new Label("Choose a Color"));
redb = new Button("RED");
redb.setBackground(Color.red);
panel2.add(redb);
blueb = new Button("BLUE");
blueb.setBackground(Color.blue);
panel2.add(blueb);
panel2.add(new Label("Choose a Function"));
fnChoice = new Choice();
fnChoice.addItem("x^2");
fnChoice.addItem("x + 30");
fnChoice.addItem("x^3");
fnChoice.addItem("x^2 + x - 52");
panel2.add(fnChoice);
add("East", panel2);
canvas = new PlotCanvas(this);
add("Center", canvas);
fromLabel = new Label("-100");
/* Bottom Panel, with from and to and status line. */
bottomPanel = new Panel();
bottomPanel.setLayout(new GridLayout(0,1,5,5));
/* Domain panel */
xdomainPanel = new Panel();
xdomainPanel.add(new Label("Plot x from : "));
fromFld = new TextField("-100", 7);
canvas.setXmin(-100);
xdomainPanel.add(fromFld);
xdomainPanel.add(new Label("to : "));
toFld = new TextField("100", 10);
canvas.setXmax(100);
xdomainPanel.add(toFld);
domainChangeb = new Button ("Change Domain");
xdomainPanel.add(domainChangeb);
bottomPanel.add(xdomainPanel);
/* Status Line */
statusPanel = new Panel();
statusLabel = new Label(" ");
statusLabel.setForeground(Color.magenta);
statusPanel.add(statusLabel);
bottomPanel.add(statusPanel);
add("South", bottomPanel);
}
/** Draws a box around this panel. */
public void paint(Graphics g) {
Dimension d = size();
g.drawRect(0,0, d.width - 1, d.height - 1);
}
public Insets insets() {
return new Insets(5,5,5,8);
}
public boolean handleEvent(Event e) {
int newFn;
try {
if ((e.target instanceof Button)
&& (e.id == Event.ACTION_EVENT)) {
if (e.target == redb) {
canvas.changeColor(Color.red);
}
else if (e.target == blueb) {
canvas.changeColor(Color.blue);
}
else if (e.target == domainChangeb) {
float newXmin = 0, newXmax = 0;
/* Do this to get rid of a possible
"Domain must be a number" message */
statusLabel.setText(" ");
newXmin = Float.valueOf(fromFld.getText()).floatValue();
newXmax = Float.valueOf(toFld.getText()).floatValue();
if (newXmax <= newXmin) {
statusLabel.setText("From must be less than To");
}
else {
canvas.setXmin(newXmin);
canvas.setXmax(newXmax);
}
}
canvas.repaint();
}
else if (e.target instanceof Choice &&
e.id == Event.ACTION_EVENT) {
newFn = fnChoice.getSelectedIndex();
canvas.setFn(newFn);
canvas.repaint();
}
}
catch (NumberFormatException e1) {
statusLabel.setText("Domain must be a number");
System.out.println(e1);
}
return false;
}
} /* End of class */
class PlotCanvas extends Canvas {
SimplePlot containedBy;
public int mousex, mousey;
public boolean isMouse = false;
int timeThrough = 0;
Color color = Color.green;
int inset = 20;
int fn = 0;
float ymax, ymin, xmax, xmin;
PlotCanvas(SimplePlot containedByIn) {
super();
containedBy = containedByIn;
xmin = -100;
xmax = 100;
}
public void changeColor (Color inColor) {
color = inColor;
}
public void setFn(int newFn) {
fn = newFn;
}
public void setXmin(float newXmin) {
xmin = newXmin;
}
public float getXmin() {
return(xmin);
}
public void setXmax(float newXmax) {
xmax = newXmax;
}
/** Draws a box around this panel, plus other stuff. */
public void paint(Graphics g) {
int x, y;
Dimension d = size();
/* These need to be made into floats. */
float xcur, ycur;
float xplot, yplot;
PlotCoord pc;
g.drawRect(0,0, d.width - 1, d.height - 1);
g.setColor(color);
/* This time through is just to find out what the max y value is. */
ymax = 0;
ymin = 0;
float stepSize = (xmax - xmin)/50;
for (xcur = xmin; xcur <= xmax; xcur += stepSize) {
/* The function we are going to plot. */
ycur = func(xcur);
if (ycur > ymax)
ymax = ycur;
if (ycur < ymin)
ymin = ycur;
}
pc = new PlotCoord (xmax, ymax, xmin, ymin, d.width, d.height, inset);
int xcoord = 0, ycoord = 0;
g.setColor(Color.black);
float xaxisStart = xmax, xaxisEnd = xmin, xaxisPosy;
float yaxisStart = ymax, yaxisEnd = ymin, yaxisPosx;;
/* Axis rules:
If 0 is on the map, print out the axis there.
If 0 is not on the map, print out the axis on the
minimum. */
if (xmin < 0 && xmax > 0)
yaxisPosx = 0;
else
yaxisPosx = xmin;
if (ymin < 0 && ymax > 0)
xaxisPosy = 0;
else
xaxisPosy = ymin ;
/* System.out.println("Yaxis at x = " + yaxisPosx +
" Xaxis at y = " + xaxisPosy);
*/
Font f = new Font ("Dialog", Font.PLAIN, 10);
g.setFont(f);
/* Draw x axis. */
g.drawLine(pc.xcoord(xaxisStart), pc.ycoord(xaxisPosy),
pc.xcoord(xaxisEnd), pc.ycoord(xaxisPosy));
/* Draw y axis. */
g.drawLine(pc.xcoord(yaxisPosx), pc.ycoord(yaxisStart),
pc.xcoord(yaxisPosx), pc.ycoord(yaxisEnd));
/* This draws one tick mark on y */
ycoord = pc.ycoord(ymin + (ymax - ymin)/2);
xcoord = pc.xcoord(yaxisPosx);
g.drawLine(xcoord+3, ycoord , xcoord - 3, ycoord);
g.drawString(
new Integer(Math.round(ymin + (ymax - ymin)/2)).toString(),
xcoord + 5, ycoord + 10);
/* This draws one tick mark on x */
xcoord = pc.xcoord(xmin + (xmax - xmin)/2);
ycoord = pc.ycoord(xaxisPosy);
g.drawLine(xcoord, ycoord + 3, xcoord , ycoord - 3);
g.drawString(
new Integer(Math.round(xmin + (xmax - xmin)/2)).toString(),
xcoord -5, ycoord + 15);
/* draw a tick at 0 if it is on the graph */
if (xmin < 0 && xmax > 0) {
xcoord = pc.xcoord(0);
ycoord = pc.ycoord(xaxisPosy);
g.drawLine(xcoord, ycoord + 3, xcoord , ycoord - 3);
g.drawString("0", xcoord -5, ycoord + 15);
}
if (ymin < 0 && ymax > 0) {
ycoord = pc.ycoord(0);
xcoord = pc.xcoord(yaxisPosx);
g.drawLine(xcoord+3, ycoord , xcoord - 3, ycoord);
g.drawString("0", xcoord + 7, ycoord + 10);
}
/* Draw tick marks at the max's. */
/* This draws one tick mark on y */
ycoord = pc.ycoord(ymax);
xcoord = pc.xcoord(yaxisPosx);
g.drawLine(xcoord+3, ycoord , xcoord - 3, ycoord);
g.drawString(
new Integer(Math.round(ymax)).toString(),
xcoord + 5, ycoord + 10);
/* This draws one tick mark on x */
xcoord = pc.xcoord(xmax);
ycoord = pc.ycoord(xaxisPosy);
g.drawLine(xcoord, ycoord + 3, xcoord , ycoord - 3);
g.drawString(
new Integer(Math.round(xmax)).toString(),
xcoord - 5, ycoord + 15);
/* end of tick marks at the max's. */
g.setColor(color);
int xcoordPrev = 0, ycoordPrev = 0;
float xprev = 0, yprev = 0;
stepSize = (xmax - xmin)/50;
for (xcur = xmin; xcur <= xmax; xcur += stepSize) {
ycur = func(xcur);
xcoord = pc.xcoord(xcur);
ycoord = pc.ycoord(ycur);
/* ie, don't do the very first x */
if (xcur != xmin) {
/*if (xcur > -0.01 && xcur < 0.01 )
System.out.println( xprev + ":" +
xcoordPrev + " " +
yprev + ":" +
ycoordPrev + " " +
xcur + ":" +
xcoord + " " +
ycur + ":" +
ycoord);*/
/* g.drawOval(xcoord-3, ycoord-3, 6, 6);*/
g.drawLine(xcoordPrev, ycoordPrev,
xcoord, ycoord);
}
xcoordPrev = xcoord;
ycoordPrev = ycoord;
xprev = xcur;
yprev = ycur;
}
}
float func( float x) {
float retval;
switch (fn) {
case 0:
retval = x * x;
break;
case 1:
retval = x + 30;
break;
case 2:
retval = x * x * x;
break;
case 3:
retval = x * x + x - 52;
break;
default:
System.out.println("Bad function number");
retval = -1;
}
return(retval);
}
/* public boolean mouseDown(Event e, int x, int y) {
Graphics gc;
gc = getGraphics();
isMouse = true;
mousex = x;
mousey = y;
System.out.println("Got a mouse event at " + x + ", " + y);
gc.setColor(color);
System.out.println(color);
System.out.println(gc.getColor());
gc.drawLine(mousex, mousey, mousex + 50, mousey + 10);
return true;
}
*/
}
class PlotCoord {
float xstretch = 1;
float ystretch = 1;
float xshift = 0;
float yshift = 0;
float ywholeScreen;
int inset; /* How far from the edge the display is */
PlotCoord(float xmax, float ymax, float xmin, float ymin,
int width, int height, int insetin ) {
inset = insetin;
xstretch = (width - (2 * inset))/ (xmax - xmin);
ystretch = (height - (2 * inset)) / (ymax - ymin);
xshift = -xmin;
yshift = -ymin;
ywholeScreen = ymax - ymin;
}
/* Return the X and Y coordinates on the canvas. */
int xcoord(float x) {
float xcoordFloat;
xcoordFloat = (x + xshift) * xstretch + inset;
return(Math.round(xcoordFloat));
}
int ycoord(float y) {
float ycoordFloat;
ycoordFloat = (ywholeScreen - (y + yshift)) * ystretch + inset;
return(Math.round(ycoordFloat));
}
}
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