在JPanel上绘制矩形 [英] Drawing rectangles on a JPanel

问题描述

我有一个JScrollPane，在它之上我有一个名为'panel1'的JPanel。
我希望在这个JPanel上绘制一些矩形。

I have a JScrollPane and on top of it I have a JPanel named 'panel1'. I want some rectangles to be drawn on this JPanel.

我有一个名为DrawRectPanel的类，它扩展了JPanel并完成了所有绘图工作。
问题在于，我尝试通过编写以下代码在panel1上绘制矩形：

I have a class named DrawRectPanel which extends JPanel and does all the drawing stuff. The problem is that, I tried to draw the rectangles on panel1 by writing the following code :

panel1.add(new DrawRectPanel());

但是没有出现在panel1
然后我试过，就像对DrawRectPanel类的测试一样：

but nothing appeared on panel1 then I tried, just as a test to the class DrawRectPanel :

JFrame frame = new JFrame();
frame.setSize(1000, 500);
Container contentPane =    frame.getContentPane();
contentPane.add(new DrawRectPanel());
frame.show();

这是有效的，并且在单独的JFrame上生成了图纸
如何绘制panel1上的矩形？
提前致谢。

This worked, and produced the drawings but on a separate JFrame How can I draw the rectangles on panel1 ? Thanks in advance.

编辑：
代码为DrawRectPanel

EDIT : code for DrawRectPanel

public class DrawRectPanel extends JPanel  {

    DrawRectPanel() {
        Dimension g = new Dimension(400,400);
        this.setPreferredSize(g);
        System.out.println("label 1");
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        System.out.println("label 2");
        g.setColor(Color.red);
        g.fillRect(20, 10, 80, 30);
    }
 }

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推荐答案

仍然不知道，

例如

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JComponent;
import javax.swing.JFrame;

public class CustomComponent extends JFrame {

    private static final long serialVersionUID = 1L;

    public CustomComponent() {
        setTitle("Custom Component Graphics2D");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void display() {
        add(new CustomComponents());
        pack();
        // enforces the minimum size of both frame and component        
        setMinimumSize(getSize());
        setVisible(true);
    }

    public static void main(String[] args) {
        CustomComponent main = new CustomComponent();
        main.display();
    }
}

class CustomComponents extends JComponent {

    private static final long serialVersionUID = 1L;

    @Override
    public Dimension getMinimumSize() {
        return new Dimension(100, 100);
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(400, 300);
    }

    @Override
    public void paintComponent(Graphics g) {
        int margin = 10;
        Dimension dim = getSize();
        super.paintComponent(g);
        g.setColor(Color.red);
        g.fillRect(margin, margin, dim.width - margin * 2, dim.height - margin * 2);
    }
}

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