how do i draw a dotted straight line on an applet.

[ravi vardhin]

how do i draw a dotted straight line on an applet.
can some one give the logic..
Thanks and regards,
ravi

[Manfred Leonhardt]

Hi Ravi,
Try the following code.

public void drawDashedLine(Graphics g,int x1,int y1,int x2,int y2,
                            double dashlength, double spacelength) 
{
   if((x1==x2)&&(y1==y2)) 
   {
     g.drawLine(x1,y1,x2,y2);
     return;
   }
   double linelength=Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
   double yincrement=(y2-y1)/(linelength/(dashlength+spacelength));
   double xincdashspace=(x2-x1)/(linelength/(dashlength+spacelength));
   double yincdashspace=(y2-y1)/(linelength/(dashlength+spacelength));
   double xincdash=(x2-x1)/(linelength/(dashlength));
   double yincdash=(y2-y1)/(linelength/(dashlength));
   int counter=0;
   for (double i=0;i<linelength-dashlength;i+=dashlength+spacelength){
       g.drawLine((int) (x1+xincdashspace*counter),
                  (int) (y1+yincdashspace*counter),
                  (int) (x1+xincdashspace*counter+xincdash),
                  (int) (y1+yincdashspace*counter+yincdash));
       counter++;
       }
   if ((dashlength+spacelength)*counter<=linelength)
      g.drawLine((int) (x1+xincdashspace*counter),
                 (int) (y1+yincdashspace*counter),
                 x2,y2);
}

Regards,
Manfred.

[Amit Agarwal]

Hi ravi, if you are running your applet thru the java plugin, you can use the BasicStroke class of the java2D api. it is available in the java.awt.geom package. Usage:

public void drawDashedLine(Graphics g1, int x1, int y1, int x2, int y2, double dashlength, double spacelength)
{
   Graphics2D g=(Graphics2D) g1;
   Stroke oldStroke=g.getStroke();
   float f[]={dashlength,spacelength};
   BasicStroke dashStroke=new BasicStroke( 1.0f, BasicStroke.CAP_SQUARE, BasicStroke.JOIN_MITER, 10.0f, f, 0.0f);
   g.draw(new Line2D.Float( x1, y1, x2, y2));
   g.setStroke(oldStroke);
}

Amit