在 JPanel 上绘制矩形

发布于 2024-12-08 23:05:29 字数 998 浏览 0 评论 0原文

我有一个 JScrollPane，在它上面有一个名为“panel1”的 JPanel。我想要在这个 JPanel 上绘制一些矩形。

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

panel1.add(new DrawRectPanel());

但 panel1 上没有出现任何内容然后我尝试了，就像对 DrawRectPanel 类的测试一样：

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

这有效，并生成了绘图，但在单独的 JFrame 上如何在 panel1 上绘制矩形？提前致谢。

编辑： DrawRectPanel 的代码

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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原文

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.

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());

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();

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

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);
    }
 }

only label 1 is printed on the screen

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金兰素衣 2024-12-15 23:05:29

仍然不知道，

例如

在此处输入图像描述

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);
    }
}

still no idea,

for example

enter image description here

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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疾风者 2024-12-15 23:05:29

而不是添加，

contentPane.add(new DrawRectPanel());

你应该这样做

contentPane.add(panel1);

，因为你已经在 panel1 中有了新的 DrawRectPanel 。但在您的代码中，您将在 contentPane 中添加另一个 DrawRectPanel 实例。并且从未在任何容器中添加panel1。

instead of adding

contentPane.add(new DrawRectPanel());

you should do

contentPane.add(panel1);

Because you already have new DrawRectPanel in panel1. But in your code you are adding another instance of DrawRectPanel in contentPane. And never added panel1 in none of your container.

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