swing step-type cursor moving

Question

I have java swing chess application. Cursor has custom view - rectangle, sized to fit whole cell. And I need cursor moving only over whole cell. Not in the limits of one cell. Is there some typical solutions for this problem? Or maybe it is possible to set with standard java capabilities step-type cursor moving?

Answer 1

I wouldn't implement some kind of "stepping" cursor. Instead I would hide the cursor completly and highlight the current cell programmatically.

• Hiding the cursor check out this question and answer.
• Use a MouseMotionListener to get the movements of the mouse (and highlight it in the paintComponent method of your custom component

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Full example below that "outputs" this screenshot:

public class StepComponent extends JComponent implements MouseMotionListener {
    private Point point = new Point(0, 0);

    public StepComponent() {
        setCursor(Toolkit.getDefaultToolkit().createCustomCursor(
                new BufferedImage(16, 16, BufferedImage.TYPE_INT_ARGB), 
                new Point(0, 0), "blank cursor"));
        addMouseMotionListener(this);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        int x = 0, y = 0;
        while (x < getWidth()) { g.drawLine(x, 0, x, getHeight()); x += 10; }
        while (y < getHeight()) { g.drawLine(0, y, getWidth(), y); y += 10; }
        if (point != null)
            g.fillRect(point.x, point.y, 10, 10);
    }
    @Override public void mouseDragged(MouseEvent e) { update(e.getPoint()); }
    @Override public void mouseMoved(MouseEvent e) { update(e.getPoint()); }

    private void update(Point p) {
        Point point = new Point(10 * (p.x / 10), 10 * (p.y / 10));
        if (!this.point.equals(point)) {
            Rectangle changed = new Rectangle(this.point,new Dimension(10,10));
            this.point = point;
            changed.add(new Rectangle(this.point, new Dimension(10, 10)));
            repaint(changed);
        }
    }
}

And some test code:

public static void main(String[] args) {

    JFrame frame = new JFrame("Test");

    frame.add(new StepComponent());

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 300);
    frame.setVisible(true);
}