How to grab a mouse in Java Swing?

Question

I'm trying to prevent mouse cursor movement (keep cursor's position at application center) and still be able to handle mouseMoved event in order to rotate a camera in space. I tried to do this with java.awt.Robot.mouseMove(int x, int y) but it calls mouseMoved event that I'm using to rotate camera, so camera returns to previous position.

You can just make two if statements: `if (mouseX > centerX)` and `else if (x < centerX)`, right?. This would prevent the method to do anything if the mouse position was reset by a robot to centerX... (Of course the same with `y` if you want to actions after the mouse moved up or down.) — Lukas Rotter, Aug 22 '15 at 19:26

score 3 · Accepted Answer · edited May 23 '17 at 11:51

And if you just ignore mouseMoved-Events called by Robot?

You could save the position, the Robot moved the mouse. If you get a Mouse-Event with exactly these mouse-coordinates, just ignore this event. For me something like this worked:

import java.awt.AWTException;
import java.awt.Robot;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;

import javax.swing.JFrame;

public class Test {
    // position, where mouse should stay
    private static final int fixX = 500;
    private static final int fixY = 500;

    private static Robot robo;
    private static JFrame frame;

    public static void main(String[] args) {
        // create robot
        try {
            robo = new Robot();
        } catch (AWTException e) {
            e.printStackTrace();
        }

        // create default frame with mouse listener
        frame = new JFrame("test frame");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.addMouseMotionListener(new MouseMotionListener() {
            @Override
            public void mouseDragged(MouseEvent arg0) {
                move(arg0);
            }

            @Override
            public void mouseMoved(MouseEvent arg0) {
                move(arg0);
            }
        });
        frame.setSize(1000, 1000);
        frame.setVisible(true);
    }

    private static void move(MouseEvent arg0) {
        // check, if action was thrown by robot
        if (arg0.getX() == fixX && arg0.getY() == fixY) {
            // ignore mouse action
            return;
        }
        // move mouse to center (important: position relative to frame!)
        robo.mouseMove(fixX + frame.getX(), fixY + frame.getY());

        // compute and print move position
        int moveX = arg0.getX() - fixX;
        int moveY = arg0.getY() - fixY;
        System.out.println("moved: " + moveX + " " + moveY);
    }
}

The mouse stays at 500/500, you get your mouse movement, but you sometimes see the mouse jumping, because Robot is not fast enough.

Maybe you could just hide the System-Cursor (How to hide cursor in a Swing application?) and draw your own cursor.

Thank you, this solved my problem. And your link is also useful for me. — Dimansel, Aug 22 '15 at 21:39

How to grab a mouse in Java Swing?

1 Answers1