MouseWheel event doesn't fire in SWT-AWT component

问题

I am stuck at mousewheel event that just doesn't fire. I use swt_awt bridge, so I am able to use swing component in my RCP application. I tested everything I was able to find, but with no success. Because my application is awfully complex, I created a simplified version of my problem, which should also help you to orientate if you would like to help me.

Now this simplified problem is, that I want my textarea (or scrollpane) to catch mousewheel events. But these events are lost.

import java.awt.Frame;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;

import javax.swing.JScrollPane;
import javax.swing.JTextArea;

import org.eclipse.swt.SWT;
import org.eclipse.swt.awt.SWT_AWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.List;
import org.eclipse.swt.widgets.Shell;


public class Main {

    protected Shell shell;

    /**
     * Launch the application.
     * @param args
     */
    public static void main(String[] args) {
        try {
            Main window = new Main();
            window.open();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Open the window.
     */
    public void open() {
        Display display = Display.getDefault();
        createContents();
        shell.open();
        shell.layout();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
    }

    /**
     * Create contents of the window.
     */
    protected void createContents() {
        shell = new Shell();
        shell.setSize(450, 300);
        shell.setText("SWT Application");
        shell.setLayout(new GridLayout(3, false));

        List list = new List(shell, SWT.BORDER);
        list.setLayoutData(new GridData(GridData.FILL_VERTICAL));
        list.add("Something");

        Composite composite = new Composite(shell, SWT.EMBEDDED);
        composite.setLayoutData(new GridData(GridData.FILL_BOTH));
        Frame graphFrame = SWT_AWT.new_Frame(composite);
        final JTextArea textarea = new JTextArea(60, 80);
        JScrollPane scrollpane = new JScrollPane(textarea);
        graphFrame.add(scrollpane);

        textarea.addMouseListener(new MouseListener() {

            @Override
            public void mouseClicked(MouseEvent arg0) {
                textarea.setText(textarea.getText() + "Mouse clicked.\n\r");
            }

            @Override
            public void mouseEntered(MouseEvent arg0) {
                textarea.setText(textarea.getText() + "Mouse is in.\n\r");
            }

            @Override
            public void mouseExited(MouseEvent arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public void mousePressed(MouseEvent arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public void mouseReleased(MouseEvent arg0) {
                // TODO Auto-generated method stub

            }

        });

        textarea.addMouseWheelListener(new MouseWheelListener() {
            @Override
            public void mouseWheelMoved(MouseWheelEvent arg0) {
                textarea.setText(textarea.getText() + "Mouse wheel activated.\n\r");
            }

        });
    }
}

EDIT: I found out, that Panel is able to catch awt events, however any class, that extends JComponent (just like my component do) somehow loose these events. I also managed to create an ugly hack, where I forceFocus on my swt composite after I click on my JComponent. Then I can at least listen to swt events and work with my JComponent directly from swt event listener. I would still aprreciate the solution where I will be able to catch awt mouse events directly on JComponent.

回答1:

You may be running into this issue: http://code.google.com/p/gama-platform/issues/detail?id=84. A workaround is described in http://code.google.com/p/gama-platform/issues/detail?id=84#c13 (linked to this very question).

来源：https://stackoverflow.com/questions/7567305/mousewheel-event-doesnt-fire-in-swt-awt-component