在 JScrollpane 中放置 JPanel

Question

我无法将 JScrollPane 中的 JPanel 一个放在另一个下面。我什至在 JScrollPane 中显示面板都没有成功，当我显示它们时，它们会全部挤在一起。 paintComponent 似乎也被完全忽略了。

您可以看到我正在尝试重新创建 Microsoft PowerPoint 之类的东西。

这是代码

public class PresentationView extends JPanel {

    private Presentation presentation;
    private JScrollPane jsp;
    private BoxLayout layout;


    public PresentationView(Presentation presentation){
        this.presentation = presentation;

        jsp = new JScrollPane(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);

        layout = new BoxLayout(this, BoxLayout.Y_AXIS);
        setLayout(layout);

        for(RuNode s: presentation.getChildren()){
            jsp.add(new SlideView((Slide) s));
            System.out.println(s.getName());
        }

        add(jsp);

    }
}

这是 SlideView class

public class SlideView extends JPanel {

    private Slide slide;
    private Image img;

    public SlideView(Slide slide){
        this(new ImageIcon(((Presentation)slide.getParent()).getImgPath()).getImage());

        setMaximumSize(new Dimension(400, 400));
        setMinimumSize(new Dimension(400, 400));
        setBackground(Color.PINK);
        setBorder(BorderFactory.createLineBorder(Color.BLACK, 5));


        this.slide = slide;
    }

    public SlideView(Image img){
        this.img = img;


    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(img, (int)(this.getSize().getWidth()-img.getWidth(null))/2,
                (int)(this.getSize().getHeight()-img.getHeight(null))/2, null);
    }
}

Answer 1

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class Main {

    public static void main(String[] args) {
        new Main();
    }

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new MainPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class MainPane extends JPanel {

        public MainPane() {
            setLayout(new BorderLayout());
            JPanel contentPane = new JPanel();
            contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));

            for (int index = 0; index < 100; index++) {
                contentPane.add(new SlidePane());
            }

            JScrollPane sp = new JScrollPane(contentPane);
            add(sp);
        }

    }

    public class SlidePane extends JPanel {

        public SlidePane() {
        }

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

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            Color c1 = new Color(0, 0, 255);
            Color c2 = new Color(0, 255, 255);
            GradientPaint gp = new GradientPaint(0, 0, c1, 0, getHeight(), c2);
            g2d.setPaint(gp);
            g2d.fillRect(0, 0, getWidth(), getHeight());

            g2d.setPaint(null);
            g2d.setColor(Color.BLUE);
            g2d.drawRect(0, 0, getWidth() - 1, getHeight() - 1);
            g2d.dispose();
        }

    }
}

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