java 覆盖paintComponent

Overriding paintComponent

提问by bob

Ok so I have been trying to figure this out for the past 26 hours with guide and online help but no success.

好的，所以我在过去 26 小时内一直试图通过指南和在线帮助解决这个问题，但没有成功。

All I want to do is draw an oval when the user clicks in the PaintPanel Please someone help so I can sleep :P

我想要做的就是在用户单击 PaintPanel 时绘制一个椭圆 请有人帮忙，这样我就可以睡觉了：P

In PaintApplet class:

在 PaintApplet 类中：

  private void PaintPanelMouseClicked(java.awt.event.MouseEvent evt) {                                        
    // TODO add your handling code here:
    if(FillRadioButton.isSelected())
    {
    PaintPanel.setBackground(JColor.getColor());
   PaintPanel.repaint();
    }
    if(BrushRadioButton.isSelected())
    {
         Point ComponentPoint = PaintPanel.getLocationOnScreen();
         PaintPanel.add(new Painter(ComponentPoint));
    }
}           

Painter Class:

画家班：

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

public class Painter extends JPanel{

Point  Component;

public Painter(Point Com)
{
    Component = Com;
}

public void paintComponent(Graphics g) 
{

        super.paint(g);
      Point CursorPoint=   MouseInfo.getPointerInfo().getLocation(); //gets cursorpoint

       int ComPX =  Component.x;
        int ComPY =  Component.y;
        int CurPX =  CursorPoint.x;
        int CurPY =  CursorPoint.y;
        int FinalX = CurPX - ComPX;
        int FinalY =  CurPY - ComPY;

       g.drawOval(FinalX, FinalY, 20, 20);




}
}

回答by Reimeus

Don't call

不要打电话

super.paint(g);

within paintComponent. This will result in an infinite loop in the paint chain mechanism. Instead you need

内paintComponent。这将导致绘制链机制无限循环。相反，你需要

super.paintComponent(g);

For better help sooner consider posting an SSCCE

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