java - 需要使用 IntelliJ 更改 GUI 的背景，但背景隐藏了按钮

Question

package imgscoring;

import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;

import static java.lang.System.exit;

public class IMGSCORING
{

    private JButton button1;
    private JPanel main;
    private JButton button2;
    private JLabel lblLed;
    private JButton button3;
    private JLabel label;
    private JLabel logo;
    private static Image i;

    public IMGSCORING() {
        button1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent actionEvent) {
                try {
                    runProgam();
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });

        button2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent actionEvent) {
                exit(1);
            }
        });

        Image i = Toolkit.getDefaultToolkit().createImage("C:\\Users\\djuwo\\Desktop\\icon.jpg");



    }

    public static void paint(Graphics g)
    {
        g.drawImage(i, 0, 0, null);
    }

    public void runProgam() throws IOException, InterruptedException  {
        QrScanner run = new QrScanner();
        run.runProgram();
    }

    public JPanel getMain() {
        return main;
    }

    public void setMain(JPanel main) {
        this.main = main;
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame(" IMG FORMING Label Generator");
        frame.setContentPane(new IMGSCORING().main);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
        ImageIcon img = new ImageIcon("C:\\Users\\djuwo\\Desktop\\icon.jpg");
        frame.setIconImage(img.getImage());

    }

    private void createUIComponents() {
        // TODO: place custom component creation code here
        logo = new JLabel(new ImageIcon("icon.jpg"));
    }
}

我对使用 Java 图形用户界面非常陌生，通过环顾四周并查看其他代码，我可以肯定地告诉我我的代码与它应有的样子相去甚远。.非常感谢有关如何正确格式化我的代码的反馈以及如何添加背景。程序正常工作，按钮响应，图标更改等。但我无法更改背景。起初我尝试了以下方法，但这显然不起作用。

frame.setContentPane(new JLabel(new ImageIcon(ImageIO.read(new File("C:\\Users\\djuwo\\Desktop\\icon.jpg"))))); 

Answer 1

在以下解决方案中，您可以看到以下步骤:

1. 重写 JPanel 的 paintComponent，以便在其背景中绘制图像。
2. 在子类 JPanel 中添加您想要的任何元素。
3. 将子类化的 JPanel 添加到 JFrame 的内容 Pane 。
4. setOpaque(false) 在子类 JPanel 中，以显示背景(我们绘制图像的位置)。

在第一个解决方案中，我只绘制图像一次，不关心调整大小时填充框架:

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Objects;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class RegularMain extends JPanel {
    private final BufferedImage bimg;

    public RegularMain(final BufferedImage bimg) {
        //super(); //FlowLayout already.
        this.bimg = Objects.requireNonNull(bimg);

        //Add your components here:
        for (int i = 1; i <= 3; ++i)
            super.add(prepare(new JButton("Button " + i)));

        //Allow pixels to show through (ie the backgroung image to be shown):
        super.setOpaque(false);

        //Preparing the preferred size:
        final Dimension prefsz = super.getPreferredSize(); //Gets the preferred size, after adding the components to this panel.
        super.setPreferredSize(new Dimension(Math.max(prefsz.width, bimg.getWidth()), Math.max(prefsz.height, bimg.getHeight())));
    }

    @Override
    protected void paintComponent(final Graphics g) {
        g.drawImage(bimg, 0, 0, this);
        super.paintComponent(g);
    }

    public static JButton prepare(final JButton button) {
        button.addActionListener(e -> JOptionPane.showMessageDialog(button, "You clicked \"" + button.getText() + "\"!"));
        return button;
    }

    public static void main(final String[] args) throws IOException {
        final JFrame frame = new JFrame("Main frame");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new RegularMain(ImageIO.read(new File("your_image.png"))));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

但是，另一种方法是调整图像大小以对应面板的大小:

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Objects;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class TransformMain extends JPanel {
    private final BufferedImage bimg;

    public TransformMain(final BufferedImage bimg) {
        //super(); //FlowLayout already.
        this.bimg = Objects.requireNonNull(bimg);

        //Add your components here:
        for (int i = 1; i <= 3; ++i)
            super.add(prepare(new JButton("Button " + i)));

        //Allow pixels to show through (ie the backgroung image to be shown):
        super.setOpaque(false);

        //Preparing the preferred size:
        final Dimension prefsz = super.getPreferredSize(); //Gets the preferred size, after adding the components to this panel.
        super.setPreferredSize(new Dimension(Math.max(prefsz.width, bimg.getWidth()), Math.max(prefsz.height, bimg.getHeight())));
    }

    @Override
    protected void paintComponent(final Graphics g) {
        final Graphics2D g2d = (Graphics2D) g.create();
        g2d.scale(getWidth() / (double) bimg.getWidth(), getHeight() / (double) bimg.getHeight());
        g2d.drawImage(bimg, 0, 0, this);
        g2d.dispose();
        super.paintComponent(g);
    }

    public static JButton prepare(final JButton button) {
        button.addActionListener(e -> JOptionPane.showMessageDialog(button, "You clicked \"" + button.getText() + "\"!"));
        return button;
    }

    public static void main(final String[] args) throws IOException {
        final JFrame frame = new JFrame("Main frame");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new TransformMain(ImageIO.read(new File("your_image.png"))));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

最后，如果您希望重复图像，另一种方法是将图像设为 TexturePaint:

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.TexturePaint;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class TextureMain extends JPanel {
    private final TexturePaint paint;

    public TextureMain(final BufferedImage bimg) {
        //super(); //FlowLayout already.
        paint = new TexturePaint(bimg, new Rectangle2D.Double(0, 0, bimg.getWidth(), bimg.getHeight()));

        //Add your components here:
        for (int i = 1; i <= 3; ++i)
            super.add(prepare(new JButton("Button " + i)));

        //Allow pixels to show through (ie the backgroung image to be shown):
        super.setOpaque(false);

        //Preparing the preferred size:
        final Dimension prefsz = super.getPreferredSize(); //Gets the preferred size, after adding the components to this panel.
        super.setPreferredSize(new Dimension(Math.max(prefsz.width, bimg.getWidth()), Math.max(prefsz.height, bimg.getHeight())));
    }

    @Override
    protected void paintComponent(final Graphics g) {
        final Graphics2D g2d = (Graphics2D) g.create();
        g2d.setPaint(paint);
        g2d.fillRect(0, 0, getWidth(), getHeight());
        g2d.dispose();
        super.paintComponent(g);
    }

    public static JButton prepare(final JButton button) {
        button.addActionListener(e -> JOptionPane.showMessageDialog(button, "You clicked \"" + button.getText() + "\"!"));
        return button;
    }

    public static void main(final String[] args) throws IOException {
        final JFrame frame = new JFrame("Main frame");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new TextureMain(ImageIO.read(new File("your_image.png"))));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

当调整框架/面板的大小时，上述解决方案的差异是可见的。在第一种情况下，框架不应该调整大小，因此我们只绘制图像一次，而不改变其大小。在第二种情况下，图像尺寸遵循面板的尺寸。在最后一种情况下，我们垂直和水平重复图像，直至达到面板的大小(通过使用 TexturePaint)。

所有情况的共同点是，我们先在 paintComponent 中绘制图像，然后将 setOpaque 设置为 false。