Question

I have a JScrollPane and JPanel inside it(I want to draw on JPanel). Also I have a method that draws lines with parametre of length of the line. I want my JScrollPane to scroll if the length of the line is more then the size(height or width) of my JPanel that is on JScrollPane.
How can I do this?

P.S. I’ve tried jScrollPane.scrollRectToVisible but it doesn’t work

Answer 1

Here is an example implementing what you want

import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class DrawLine {

    JFrame j;
    JPanel p;
    JScrollPane sp;

    public DrawLine() {
        j = new JFrame();
        p = new JPanel() {
            public void paintComponent(Graphics g) {
                g.drawLine(20, 20, 250, 250);
            }
        };
        p.setPreferredSize(new Dimension(300, 300));
        sp = new JScrollPane(p);
        j.getContentPane().add(sp);
        j.setSize(300, 300);
        j.setVisible(true);
    }

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

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Note the line p.setPreferredSize(new Dimension(300, 300)); which sets the preferred size of the panel.