// To run this applet, click on circles.html.
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class circles extends Applet implements AdjustmentListener
{
private int radius;
Scrollbar sizes;
private circle first, second;
private point center;
Graphics page;
public void init ()
{
setBackground
(Color.cyan);
center = new
point (150, 100);
radius = 10;
first = new
circle (center, radius);
setLayout
(null);
sizes = new
Scrollbar (Scrollbar.HORIZONTAL, 0, 1, 0, 50);
sizes.addAdjustmentListener
(this);
sizes.setBounds
(50, 200, 200, 15);
add (sizes);
page = getGraphics
();
}
public void adjustmentValueChanged
(AdjustmentEvent event)
{
if (event.getAdjustable
() == sizes)
{
page.setColor (Color.cyan);
first.drawCircle (page);
radius = sizes.getValue ();
second = new circle (center,radius);
page.setColor (Color.blue);
second.drawCircle (page);
first = second;
}
}
} // class circles
class point
{
private int x, y;
point (int x, int y)
{
this.x = x;
this.y = y;
}
int get_x ()
{return x;}
int get_y ()
{return y;}
void set_xy (int x, int y)
{
this.x = x;
this.y = y;
}
}// class point
class circle
{
private point center;
private int radius;
circle (point center, int radius)
{
this.center
= center;
this.radius
= radius;
}
public void drawCircle (Graphics page)
{
int x, y;
x = center.get_x ();
y = center.get_y ();
page.drawOval (x-radius,
y-radius, 2*radius, 2*radius);
}
} // class circle