Interactive graphics - An Introduction to Graphical User Interfaces with Java Swing - page 67

addCircle(circ) adds circle circ to vector circles .

removeNearestCircle(x1,y1) determines a circle stored in vector circles
whose centre has minimum distance to the point ( x

,

y ). If the distance is at
most 30 (pixel), then the circle is removed from circles .
drawAll(g) draws all circles currently stored in circles . This is done by calling
the draw -method of each of them. The Graphics object g is passed on.
getNoOfCircles() returns the number of circles currently stored in vector cir-
cles .

In method removeNearestCircle(x1,y1) the circle to be removed is found by
computing the distances of the point ( x 1 , y 1 )tothe centre of all circles. This

is not the most effective way of doing this but we choose it to keep the code
short.

File: its/InteractiveGraphic/CircleAdministration.java

package its.InteractiveGraphic; 1.

2.
3.

import java.awt.Graphics;

import java.util.Vector; 4.

5.
6. public class CircleAdministration

{ 7.

private Vector circles; 8.

9.
10. public CircleAdministration()

11.

{

12.

circles = new Vector();

13.

}

14.
15. public void addCircle(Circle circ)

16.

{

17.

circles.add(circ);

18.

}

19.
20. public void removeNearestCircle( int x1, int y1)

21.

{

22.

Circle circ;

double minDist = Double.MAX_VALUE; 23.

int minDistIndex = -1; 24.

for ( int i=0;i<circles.size() ; i++) 25.

{ 26.

circ = (Circle)(circles.get(i)); 27.

if (circ.distanceTo(x1,y1) < minDist) 28.