Resizing 2D graphics on the JPanel

[dkim18]

I have a class called Graph and all drawing functionality and resize/redrawing behavior is encapsulated in this class. So, I have created a graph by using 2D graphics on JPanel (instance of JInternal Frame)and want the graph to be resizable when the user dragging the corners of the window.

Any idea?
-----------------------
public class HW2 extends JApplet {


private JDesktopPane theDesktopPane;
Dimension component_dimen = new Dimension(100, 100);
public void init() {

setBackground(Color.gray);

theDesktopPane = new JDesktopPane();
getContentPane().add(theDesktopPane);

JInternalFrame frame = new JInternalFrame("Home Work2", true, true, true, true);
Container container = frame.getContentPane();
//---------------------
Graph topPanel = new Graph((new Dimension (400, 400)), // size
0, // minX
0, // minY
200.0, // maxX
1.0, // maxY
"Sin and Cos", // title
"X", // x label
"Y", // y label
20.0, // tick X
0.1, // tick Y
// "##0", // format axis X
//"##0.00" ); // format axis Y
new DecimalFormat( "##0" ),
new DecimalFormat( "##0.00&quot );
container.add(topPanel, BorderLayout.CENTER);
//this.validate();
frame.setMinimumSize(component_dimen);
//frame.resi
frame.pack();
theDesktopPane.add(frame);
frame.setVisible(true);
setSize(400, 400);
setVisible(true);
}
------------------------------

 

[prosper]

//Please look at this example from

http://merganser.math.gvsu.edu/david/reed03/lectures/package.html

// CubicPanel.java
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;

public class CubicPanel extends JPanel {
Grid grid;
CubicFunction function;
AffineTransform transform;
int width = 0, height = 0;
BoundingBox bbox;

public CubicPanel(double llx, double lly, double urx, double ury) {
setBackground(Color.white);
bbox = new BoundingBox(llx, lly, urx, ury);
grid = new Grid(this);
function = new CubicFunction(this);
}

public void paintComponent(Graphics gfx) {
super.paintComponent(gfx);
Rectangle size = getBounds();
Graphics2D g = (Graphics2D) gfx;
if (size.width != width || size.height != height) {
width = size.width; height = size.height;
float ratioX = (float) (width / (bbox.urx - bbox.llx));
float ratioY = (float) (-height /(bbox.ury - bbox.lly));
transform = new AffineTransform();
transform.scale(ratioX, ratioY);
transform.translate(-bbox.llx, -bbox.ury);
}
grid.plot(g);
function.plot(g);
}

public BoundingBox getBoundingBox() {
return bbox;
}

public AffineTransform getTransform() {
return transform;
}

public static void main(String[] args) {
JFrame frame = new JFrame("CubicPanel");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
CubicPanel cubic = new CubicPanel(-2, -3, 2, 3);
frame.getContentPane().add(cubic, BorderLayout.CENTER);
cubic.setPreferredSize(new Dimension(300, 300));
frame.pack();
frame.show();
}
}
// Grid.java
import java.awt.*;
import java.awt.geom.*;

public class Grid {
CubicPanel panel;

public Grid(CubicPanel cp) {
panel = cp;
}
public void plot(Graphics2D g) {
BoundingBox bbox = panel.getBoundingBox();
GeneralPath path = new GeneralPath();
int minX = (int) Math.floor(Math.min(bbox.llx, bbox.urx));
int maxX = (int) Math.ceil(Math.max(bbox.llx, bbox.urx));
for (int x = minX; x <= maxX; x++) {
path.moveTo(x, (float) bbox.lly);
path.lineTo(x, (float) bbox.ury);
}
int minY = (int) Math.floor(Math.min(bbox.lly, bbox.ury));
int maxY = (int) Math.ceil(Math.max(bbox.lly, bbox.ury));
for (int y = minY; y <= maxY; y++) {
path.moveTo((float) bbox.llx, y);
path.lineTo((float) bbox.urx, y);
}
AffineTransform transform = panel.getTransform();
g.draw(transform.createTransformedShape(path));
}
}
//CubicFunction.java
import java.awt.*;
import java.awt.geom.*;

public class CubicFunction {
CubicPanel panel;

public CubicFunction(CubicPanel cp) {
panel = cp;
}

public void plot(Graphics2D g) {
BoundingBox bbox = panel.getBoundingBox();
AffineTransform transform = panel.getTransform();
int steps = 50;
double stepsize = (bbox.urx - bbox.llx)/steps;
GeneralPath path = new GeneralPath();
path.moveTo((float) bbox.llx, (float) valueAt(bbox.llx));
for (int i = 1; i <= steps; i++) {
double x = bbox.llx + i*stepsize;
path.lineTo((float) x, (float) valueAt(x));
}
g.setPaint(Color.black);
g.draw(transform.createTransformedShape(path));
}

public double valueAt(double x) {
return x*x*x - x;
}
}
// BoundingBox.java
public class BoundingBox {
public double llx, lly, urx, ury;
public BoundingBox(double lowerLeftX, double lowerLeftY,
double upperRightX, double upperRightY) {
llx = lowerLeftX; lly = lowerLeftY;
urx = upperRightX; ury = upperRightY;
}
}