Bresenham line drawing algorithm in java

   My friend Sandip is doing M.Tech from one of the reputed college. His lecturer asked him to do Java code for line drawing using Bresenham s , DDA algorithm. So I am posting this blog for  Bresenham line drawing algorithm in java and you can find line drawing using DDA algorithm  here.

Read more about Bresenham's line algorithm  .

Java code :- 

package applet;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

public class bresenhamLine extends java.applet.Applet implements MouseListener, MouseMotionListener {

private static final long serialVersionUID = 1L;
int width, height;
int x1 = 0, y1 = 0, x2 = 0, y2 = 0, pixelsize = 2;
public void init() {
     width = getSize().width;
     height = getSize().height;
     this.addMouseListener(this);
      this.addMouseMotionListener(this);
 
  }
// draw a line from point x1,y1 into x2,y2
public void bresenham_line(int x1, int y1, int x2, int y2) {
// if point x1, y1 is on the right side of point x2, y2, change them
if ((x1 - x2) > 0) {bresenham_line(x2, y2, x1, y1); return;}
// test inclination of line
// function Math.abs(y) defines absolute value y
if (Math.abs(y2 - y1) > Math.abs(x2 - x1)) {
// line and y axis angle is less then 45 degrees
// that swhy go on the next procedure
bresteepline(y1, x1, y2, x2); return;
}
// line and x axis angle is less then 45 degrees, so x is guiding
// auxiliary variables
int x = x1, y = y1, sum = x2 - x1, Dx = 2 * (x2 - x1), Dy = Math.abs(2 * (y2 - y1));
int prirastokDy = ((y2 - y1) > 0) ? 1 : -1;
// draw line
for (int i = 0; i <= x2 -x1; i++) {
setpix(x, y);
x++;
sum -= Dy;
if (sum < 0) {y = y + prirastokDy; sum += Dx;}
}
}

public void bresteepline(int x3, int y3, int x4, int y4) {
// if point x3, y3 is on the right side of point x4, y4, change them
if ((x3 - x4) > 0) {bresteepline(x4, y4, x3, y3); return;}

int x = x3, y = y3, sum = x4 - x3, Dx = 2 * (x4 - x3), Dy = Math.abs(2 * (y4 - y3));
int prirastokDy = ((y4 - y3) > 0) ? 1 : -1;

for (int i = 0; i <= x4 -x3; i++) {
setpix(y, x);
x++;
sum -= Dy;
if (sum < 0) {y = y + prirastokDy; sum += Dx;}
}
}

public void setpix(int x, int y)
    {
 Graphics g =getGraphics();
 g.setColor(Color.green );
 g.fillRect(pixelsize * x, pixelsize * y, pixelsize, pixelsize);
    }
public void paint( Graphics g )
     {
        Dimension d = getSize();

        g.drawLine(0,0,d.width,0);
        g.drawLine(0,0,0,d.height);
        g.drawLine(d.width-1,d.height-1,d.width-1,0);
        g.drawLine(d.width-1,d.height-1,0,d.height-1);
        bresenham_line(x1, y1, x2, y2);
        }
    public void mousePressed(MouseEvent e)
     {
x1 = e.getX()/pixelsize;
y1 = e.getY()/pixelsize;
     }
    public void mouseDragged(MouseEvent e)
     {
x2 = e.getX()/pixelsize;
y2 = e.getY()/pixelsize;
repaint();
     }

     public void mouseReleased(MouseEvent e) {;}
     public void mouseClicked(MouseEvent e) {;}
     public void mouseEntered(MouseEvent e) {;}
     public void mouseExited(MouseEvent e) {;}
     public void mouseMoved(MouseEvent e) {;}

}


copy this code and run in eclipse using Java applet.