java - Passing the click event on one jPanel to another JPanel

Question

I have one outer panel, in the outer panel I have another jPanel placed on it.

if i do a right click on the inner panel, outer panel's right click action should happen. if i do left click on the inner panel, its own inner panel's click action should happen.

Is it possible to pass click event from one panel to another panel?

Answer 1

There are a number issues you need to resolve for this to work.

The first is understanding that a mouse event is contextual to the component that created it, in particular, the location information. The click point is the offset from the source components x/y position (which will be 0x0 for the mouse event). This means if you want to redispatch the event, you need to, at least, translate the location context into the parent components space.

The source component should also be changed. Failing to do this could cause issues for other parts of the API that may rely on it to make determinations (such as a popup, which will want to translate the location information from the component space to the screen space).

Secondly, you should make no assumptions about the parent. That is, you should make no assumption that the parent may or may not implement a mouse listener interfaces.

A possible solution would be to use SwingUtilities.convertMouseEvent to convert the MouseEvent raised in the inner panel to be compatible with the outer panel and then use Component#dispatchEvent to mimick the standard event handling process, for example...

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class TestTree {

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

    public TestTree() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new OutterPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class InnerPane extends JPanel {

        public InnerPane() {
            setBackground(Color.RED);
            addMouseListener(new MouseAdapter() {

                @Override
                public void mouseClicked(MouseEvent e) {
                    System.out.println("Inner was clicked at : " + e.getPoint());
                    MouseEvent convertMouseEvent = SwingUtilities.convertMouseEvent(e.getComponent(), e, getParent());
                    getParent().dispatchEvent(convertMouseEvent);
                }

            });
        }

    }

    public class OutterPane extends JPanel {

        public OutterPane() {
            setLayout(new BorderLayout());
            setBorder(new EmptyBorder(10, 10, 10, 10));
            add(new InnerPane());

            addMouseListener(new MouseAdapter() {

                @Override
                public void mouseClicked(MouseEvent e) {
                    System.out.println("Outter was clicked at : " + e.getPoint());
                }

            });
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }

}