java - 在Java中绘制带有尖角的边界路径

Question

我正在开发一个在地图上显示 GPS 轨迹的应用程序。我想将轨道绘制为任意厚度的彩色路径。我发现这GeneralPath门课似乎在做我想做的事。但是，我希望彩色路径也有黑色边框。我找不到任何关于如何为路径添加边框的信息，所以我想出了一个快速的 hacky 解决方案，首先绘制一条粗黑色路径，然后在顶部绘制一条细彩色路径。

SSCCE：

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.GeneralPath;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class PathBorder {
    private JFrame frame;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    PathBorder window = new PathBorder();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public PathBorder() {
        initialize();
    }

    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 450, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel() {
            protected void paintComponent(Graphics g) {
                GeneralPath path;
                Graphics2D g2d = (Graphics2D) g;
                g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                        RenderingHints.VALUE_ANTIALIAS_ON);
                g2d.setStroke(new BasicStroke(5.5f));
                g2d.setColor(Color.BLACK);
                path = new GeneralPath();
                path.moveTo(0, 0);
                path.lineTo(100, 100);
                path.lineTo(200, 100);
                path.lineTo(100, 80);
                g2d.draw(path);
                g2d.setStroke(new BasicStroke(3));
                g2d.setColor(Color.YELLOW);
                g2d.draw(path);
            }
        };
        frame.setBackground(Color.CYAN);
        frame.add(panel);
    }
}

这是一张图片（取自 SSCCE）来突出我的问题。请看下面的红色圆圈，注意外部边框是如何有间隙的。我希望填补这个空白，以便边界是连续的。

以下是我的真实曲目应用程序的一些实际屏幕截图：

如果你仔细观察赛道右下角的急弯，你会发现边界会短暂丢失……下面的详细图片让它更加清晰。

我不确定如何解决这个问题，但我愿意接受建议，要么保持GeneralPath策略，要么完全使用不同的想法。

Answer 1

试验cap和join参数以获得更好的效果。例如

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.GeneralPath;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class PathBorder {

    private JFrame frame;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            public void run() {
                try {
                    PathBorder window = new PathBorder();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public PathBorder() {
        initialize();
    }

    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 450, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel() {

            GeneralPath path;

            protected void paintComponent(Graphics g) {
                Graphics2D g2d = (Graphics2D) g;
                g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                        RenderingHints.VALUE_ANTIALIAS_ON);
                BasicStroke s = new BasicStroke(
                        5.5f, 
                        BasicStroke.CAP_ROUND, 
                        BasicStroke.JOIN_ROUND);
                g2d.setStroke(s);
                g2d.setColor(Color.BLACK);
                if (path==null) {
                    path = new GeneralPath();
                    path.moveTo(0, 0);
                    path.lineTo(100, 100);
                    path.lineTo(200, 100);
                    path.lineTo(100, 80);
                }
                g2d.draw(path);
                g2d.setStroke(new BasicStroke(3));
                g2d.setColor(Color.YELLOW);
                g2d.draw(path);
            }
        };
        frame.setBackground(Color.CYAN);
        frame.add(panel);
    }
}