Name: boT120536 Date: 03/20/2001


java version "1.2.2"
Solaris VM (build Solaris_JDK_1.2.2_05a, native threads, sunwjit)

/*
There appears to be a bug in the way that Polygon.contains() works. This
bug only surfaces if you manually change (by poking around in the
xpoints/ypoints arrays) the vertices of the polygon.

This program prints:

     true
     true
     false

thereby illustrating that contains does not work properly if the
array data in the polygon is changed manually!

*/

import java.awt.*;

public class Translate {

    public static void main(String[] args) {
        int dist = 2;
        Point center = new Point(10, 20);

        // make a triangle centered at center of height 2 * dist
        Polygon triangle = new Polygon();
        triangle.addPoint(center.x - dist, center.y - dist);
        triangle.addPoint(center.x + dist, center.y - dist);
        triangle.addPoint(center.x, center.y + dist);

        // test contains
        System.out.println(triangle.contains(center));

        // translate the triangle and the center and test contains again
        triangle.translate(dist, dist);
        center.translate(dist, dist);
        System.out.println(triangle.contains(center));

        // same thing, only this time do the translation manually
        for (int i = 0; i < triangle.npoints; i++) {
            triangle.xpoints[i] += dist;
            triangle.ypoints[i] += dist;
        }
        center.translate(dist, dist);
        System.out.println(triangle.contains(center));
    }

}
(Review ID: 119031)
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