CODEWITHSUNDEEP
javaswingaffinetransform
Tesla
Tesla

Reputation: 822

Determine if mouseclicked inside a rotated rectangle in Java (AWT, swing)

I am having some trouble figuring out how to determine if a mouseclick event was clicked inside of a rectangle, if the rectangle has been rotated.

Lets say I have a MouseAdapter as simple as this. It just prints out a statement saying that we hit inside the rectangle if the mousePressed was in fact within the rectangle.

MouseAdapter mAdapter = new MouseAdapter() {
    public void mousePressed(MouseEvent e) {
        int xPos = e.getX();
        int yPos = e.getY();
        if(xPos >= rect.x && xPos <= rect.x + rect.width && yPos >= rect.y && yPos <= rect.y + rect.height) {
            System.out.println("HIT INSIDE RECTANGLE");
        }
    }
};

My issue comes from when I rotate the rectangle. The if statement above obviously doesn't consider the rotation, so after I rotate the rectangle, my hit test fails. For rotate, I'm doing something as simple as this in a paint() function:

class drawRect {

    Rectangle rect = new Rectangle();

    ...

    public void paint(Graphics g) {
        Graphcis2D g2 = (Graphics2D) g;
        AffineTransform old = g2.getTransform();
        g.rotate(Math.toRadians(90), rect.x, rect.y); 
        g2.draw(rect);
        g2.setTransform(old);
    }
}

This is just some quick pseudocode, so that you guys can understand what I am trying to do. So please don't worry about syntax and all of that. Any help would be appreciated!

Upvotes: 0

Views: 2194

Answers (1)

Mike Tunnicliffe
Mike Tunnicliffe

Reputation: 10772

You could apply the rotation to your mouse coordinates as well. Dry-coded:

MouseAdapter mAdapter = new MouseAdapter() {
    public void mousePressed(MouseEvent e) {
        // Create the same transform as used for drawing the rectangle
        AffineTransform t = new AffineTransform();
        t.rotate(Math.toRadians(90), rect.x, rect.y);
        Point2D tp = t.inverseTransform(e.getPoint());

        if(rect.contains(tp)) {
            System.out.println("HIT INSIDE RECTANGLE");
        }
    }
};

Upvotes: 2

Related Questions