使用Java的Path2D创建钢笔工具的问题

我一直在尝试使用Path2D类和鼠标监听器为我的Java绘图程序创建一个笔工具，但我有令人困惑的结果。 该工具将工作几秒钟，但随后整个应用程序将冻结，必须关闭。 （这里没有例外;程序只是冻结）。 这是一个certificate问题的SSCCE：

import java.awt.BasicStroke; import java.awt.event.MouseAdapter; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Point; import java.awt.Shape; import java.awt.event.MouseEvent; import java.awt.geom.Path2D; import javax.swing.JFrame; import javax.swing.JPanel; public class PenDemoPanel extends JPanel { private Point start; private Point stop; private Shape shape; public PenDemoPanel() { setBackground(Color.white); setPreferredSize(new Dimension(600, 600)); PathListener listener = new PathListener(); addMouseListener(listener); addMouseMotionListener(listener); } public void paintComponent(Graphics gc) { super.paintComponent(gc); Graphics2D g2 = (Graphics2D) gc; if (start != null && stop != null) { BasicStroke stroke = new BasicStroke(1); shape = stroke.createStrokedShape(shape); g2.draw(shape); g2.fill(shape); } } private class PathListener extends MouseAdapter { public void mousePressed(MouseEvent event) { start = event.getPoint(); Path2D path = new Path2D.Double(); shape = path; } public void mouseDragged(MouseEvent event) { stop = event.getPoint(); Path2D path = (Path2D) shape; path.moveTo(start.x, start.y); path.lineTo(stop.x, stop.y); shape = path; start = stop; repaint(); } public void mouseReleased(MouseEvent event) { Path2D path = (Path2D) shape; path.closePath(); shape = path; repaint(); } } public static void main(String[] args) { PenDemoPanel shapes = new PenDemoPanel(); JFrame frame = new JFrame("PenDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(shapes); frame.pack(); frame.setVisible(true); } } 

我编写了自己的Path类，它在这里工作得很好，但我想使用Path2D类中的一些附加function。

我在这里做错了什么，或者Path2D不具备我想做的事情？

任何帮助将不胜感激。

Answer 1

问题似乎来自于将描边形状分配回形状。 如果你避免这样做，应用程序。 保持敏感。 可见。

 import java.awt.BasicStroke; import java.awt.event.MouseAdapter; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Point; import java.awt.Shape; import java.awt.event.MouseEvent; import java.awt.geom.Path2D; import javax.swing.*; public class PenDemoPanel extends JPanel { private Point start; private Point stop; private Shape shape; public PenDemoPanel() { setBackground(Color.white); setPreferredSize(new Dimension(600, 600)); PathListener listener = new PathListener(); addMouseListener(listener); addMouseMotionListener(listener); } public void paintComponent(Graphics gc) { super.paintComponent(gc); Graphics2D g2 = (Graphics2D) gc; if (start != null && stop != null) { BasicStroke stroke = new BasicStroke(1); Shape strokedShape = stroke.createStrokedShape(shape); g2.draw(strokedShape); g2.fill(strokedShape); } } private class PathListener extends MouseAdapter { public void mousePressed(MouseEvent event) { start = event.getPoint(); Path2D path = new Path2D.Double(); shape = path; } public void mouseDragged(MouseEvent event) { stop = event.getPoint(); Path2D path = (Path2D) shape; path.moveTo(start.x, start.y); path.lineTo(stop.x, stop.y); shape = path; start = stop; repaint(); } public void mouseReleased(MouseEvent event) { Path2D path = (Path2D) shape; try { path.closePath(); } catch(Exception ingore) { } shape = path; repaint(); } } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { PenDemoPanel shapes = new PenDemoPanel(); JFrame frame = new JFrame("PenDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(shapes); frame.pack(); frame.setVisible(true); } }); } }