mouse motion listener only in one direction

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粉色の甜心 2020-12-07 00:28

i have been working on mouse motion listener in Java couldn\'t sort it out completely because i want the object to move towards the direction where ever on the screen the mo

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悲哀的现实 (楼主)

2020-12-07 00:45

This:

  if (xpos < 0) {

means "if the cursor is outside of the panel".

This:

  xpos = getX();

does not get a mouse coordinate.

Change your event to something like this:

public void mouseMoved(MouseEvent e) {
    xpos = e.getX();
    if (xpos < getWidth() / 2) {
        polyrot--;
    } else {
        polyrot++;
    }
    repaint();
}

Now it rotates counter-clockwise if the cursor is on the left side of the panel and clockwise if the cursor is on the right side.

This:

  g2d.draw(poly);
  g2d.translate(width / 2, height / 2);
  g2d.rotate(Math.toRadians(polyrot));
  g2d.scale(5, 5);

will not do anything to change the image because you are doing your transforming after drawing it.

This:

  Graphics2D g2d = (Graphics2D) g;

is a bad idea because you are applying transforms to the global graphics context which would carry on to subsequent repaints of other components.

Change your paint to something like this:

public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g.create();
    width = getSize().width;
    height = getSize().height;
    g2d.setColor(Color.BLACK);
    g2d.fillRect(0, 0, width, height);
    g2d.translate(width / 2, height / 2);
    g2d.rotate(Math.toRadians(polyrot));
    g2d.scale(5, 5);
    g2d.setColor(Color.RED);
    g2d.draw(poly);
    g2d.dispose();
}