Looking for a rotation widget for java

Question

I have a function in my java app that rotates an image by x degrees. Right now I pop up a simple JOptionPane that collects the rotation angle as a double from the user.

Is there a java widget that would allow the user to click / drag to a point on a circle to set the rotation angle visually?

Already checked out: AWT, SWT, Swing

Answer 1

Why not create one yourself? It should be fairly simple to do. Here is a quick draft i made in a few minutes... You can change it to your liking:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.event.MouseMotionListener;
import java.awt.geom.AffineTransform;

import javax.swing.JFrame;
import javax.swing.JPanel;


/**
 * @author Savvas Dalkitsis
 */
public class Test {

    public static void main(String[] args) {
        JFrame f = new JFrame("Test");
        final JRotation rot = new JRotation();
        f.getContentPane().add(rot);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setVisible(true);
        rot.addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {
                System.out.println(rot.getRotation());
            }
        });
    }

}

@SuppressWarnings("serial")
class JRotation extends JPanel implements MouseMotionListener {

    private double rotation = 1;
    public double getRotation() {
        return rotation;
    }

    public JRotation() {
        setPreferredSize(new Dimension(100, 100));
        addMouseMotionListener(this);
    }

    @Override
    protected void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D)g.create();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.white);
        g2.fillRect(0, 0, getWidth(), getHeight());
        g2.setPaint(Color.black);
        AffineTransform t = g2.getTransform();
        g2.translate(getWidth()/2, getHeight()/2);
        g2.rotate(-rotation);
        g2.drawLine(0, 0, Math.max(getWidth(),getHeight()), 0);
        g2.setTransform(t);
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        int x = e.getX();
        int y = e.getY();
        int midX = getWidth() / 2;
        int midY = getHeight() / 2;
        if (x>midX) {
            if (y>midY) { // fourth quadrant
                rotation = 2*Math.PI - Math.atan((y-midY)/(double)(x-midX));
            } else { // first quadrant
                rotation = Math.atan((midY-y)/(double)(x-midX));
            }
        } else {
            if (y>midY) { // third quarter
                rotation = Math.PI + Math.atan((y-midY)/(double)(midX-x));
            } else { // second quarter
                rotation = Math.PI - Math.atan((midY-y)/(double)(midX-x));
            }
        }
        repaint();
    }

    public void mouseMoved(MouseEvent e) {}

}