java swing：多边形填充颜色问题 [英] java swing : Polygon fill color problem

问题描述

任何人都可以诊断出我面临的问题吗？
当您运行演示时，您可以看到中间部分留空，我需要填充整个区域..

Could any body diagnose the problem I am facing? As you run the demo you can see the middle part left blank, I need to fill the entire area..

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class FillDemo
{
    public static void main(String aths[])
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel pnl = new PolygonDemo();
        pnl.setSize(100, 200);
        f.getContentPane().add(pnl);
        f.setSize(400,280);
        f.setLocation(200,200);
        f.setVisible(true); 
    }
}

class PolygonDemo extends JPanel
{
    public PolygonDemo()
    {
        setBackground(Color.white);
    }

    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        Polygon p=new Polygon();

        p.addPoint(100,0);
        p.addPoint(100,100);
        p.addPoint(0,100);
        p.addPoint(0,0);

        p.addPoint(80,0);
        p.addPoint(80,20);
        p.addPoint(40,20);
        p.addPoint(40,40);
        p.addPoint(80,40);
        p.addPoint(80,100);
        p.addPoint(20,100);
        p.addPoint(20,80);
        p.addPoint(60,80);
        p.addPoint(60,60);
        p.addPoint(20,60);
        p.addPoint(20,0);
        p.addPoint(0,0);

        g2.setColor(Color.BLACK);
        g2.draw(p);
        g2.setColor(new Color(120,250,100));
        g2.fillPolygon(p);
        //g2.fillPolygon(p.xpoints,p.ypoints,p.npoints);

    }

}

非常感谢提前

推荐答案

您的多边形与自身相交。 fillPolygon方法无法清楚地确定哪个点在哪个点以及哪个点在哪个点。来自fillPolygon javadoc：

Your polygon intersects with itself. The fillPolygon method can not clearly decide which point is in and which is out. From the fillPolygon javadoc:

多边形内的区域使用偶数填充规则定义，也称为交替规则。 / p>

The area inside the polygon is defined using an even-odd fill rule, also known as the alternating rule.

也许您可以将多边形分成三个单一的多边形。

Perhaps you can split your polygon into three single ones.

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