Same 20% opaque color for poly fill and wide border cause unwanted darker color

Name: gsC80088 Date: 02/10/99


If I draw a polygon with the same 20% opaque color for a polygon and it's wide border (BasicStroke 45f), the area where the
border overlaps the fill produces an unwanted darker color.

This bug is best understood by seeing an image of the result:
bug.jpeg

This image and an associated readme may be found at

ftp://ncrds.er.usgs.gov/pub/java2d_bug/

log in as "anonymous".
                                 
CODE:

final static Color trgreen = new Color(0,255,0,50);
final static BasicStroke stroke = new BasicStroke(2.0f);
final static BasicStroke wideStroke = new BasicStroke(45.0f,
                                        BasicStroke.CAP_ROUND,
                                        BasicStroke.JOIN_ROUND);

/* Clockwise outer polygon */

        GeneralPath p1 = new GeneralPath(GeneralPath.WIND_NON_ZERO);

        p1.moveTo( w * .25f, h * 0.2f);
        p1.lineTo( w * .75f, h * .5f);
        p1.lineTo( w * .25f, h * .8f);
        p1.lineTo( w * .2f, h * .5f);
        p1.closePath();

/* Counter-clockwise polygon hole */

        p1.moveTo( w * .25f, h * 0.4f);
        p1.lineTo( w * .35f, h * .63f);
        p1.lineTo( w * .5f, h * .5f);
        p1.closePath();

        g2.setStroke(wideStroke);
        g2.setColor(trgreen);
        g2.fill(p1);
        g2.setColor(trgreen);
        g2.draw(p1);
(Review ID: 48844)
======================================================================