Drawing Lines
The drawLine method belongs to the Graphics class.
This example draws a fan of twenty lines from the bottom center of the Applet along the top edge. The applet's getSize method is used to find the dimensions of the applet.
Code: JAVA
import java.awt.*;
import java.applet.*;
public class LineExample extends Applet
{
public LineExample()
{
this.setBackground(new Color(255, 255, 255));
this.setForeground(new Color(255, 0, 0));
}
public void paint(Graphics g)
{
// Get the width and height of the Applet
int width = this.getSize().width;
int height = this.getSize().height;
// Fan 20 lines from the bottom-middle, across the top
for (int counter=0; counter<=width; counter+=(width/20))
g.drawLine(width/2, height, counter, 0);
}
}
Drawing Ovals
The drawOval method belongs to the Graphics class.
The drawOval method takes four parameters; x, y, width, and height. The following example draws an oval, half the size of the applet, in the center of the applet.
Code: JAVA
import java.awt.*;
import java.applet.*;
public class OvalExample extends Applet
{
public OvalExample()
{
this.setBackground(new Color(255, 255, 255));
this.setForeground(new Color(255, 0, 0));
}
public void paint(Graphics g)
{
// Get the width and height of the Applet
int width = this.getSize().width;
int height = this.getSize().height;
g.drawOval(width/4, height/4, width/2, height/2);
}
}
Freehand Drawing
In the previous examples, the paint method was used to display graphics on the applet. The paint method has a parameter for the graphics context, but you may wish to use the graphics context in other methods that don't have a graphics parameter. The getGraphics method is used to return the graphics context for a component, which in this case is the applet.
Graphics g = this.getGraphics();
Freehand Example:
The following example uses the getGraphics method for free-hand drawing. The example uses a MouseListener, and a MouseMotionListener, which are part of the Java 1.1 Event Model.
Code: JAVA
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class FreehandExample extends Applet implements MouseListener, MouseMotionListener
{
private Point start, end;
public FreehandExample()
{
this.setBackground(new Color(255, 204, 0));
this.setForeground(new Color(51, 153, 204));
// Add the Event Listeners
this.addMouseListener(this);
this.addMouseMotionListener(this);
}
// Capture the mousePressed event
public void mousePressed(MouseEvent e)
{
start = new Point(e.getX(), e.getY());
}
// Define the other events for MouseListener
public void mouseClicked(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
// Capture the mouseDrag event
public void mouseDragged(MouseEvent e)
{
// Get the current state of the graphics
Graphics g = this.getGraphics();
end = new Point(e.getX(), e.getY());
g.drawLine(start.x, start.y, end.x, end.y);
start = end;
}
// Define the other events for MouseMotionListener
public void mouseMoved(MouseEvent e) {}
}