Question

I’ve had a look around for this problem but couldn’t find an answer…

I currently have a JPanel in which I’m painting a load of unicode characters (music notes) using the Graphics2D g2.drawString() method.

I have an ArrayList of KeyPress objects, each of which contains one or more g2.drawString() calls.

So each KeyPress object is a music note and is painted on the JPanel.

How would I go about adding the functionality to enable the user to select and drag the objects?

Answer 1

See the tutorial on supporting user interaction. It comes down to determining which (if any) objects were underneath the mouse when it was clicked and held. On a drag event, the selected object is moved and the canvas is repainted.

You can obtain the bounds of the string by using FontMetrics:

String text = "Hello world!";
Rectangle2D bounds = g2.getFontMetrics().getStringBounds(text, g2);

I assume the rectangle top-left will be (0, 0), so you need to add (x, y) to it (where x, y are the parameters you passed to drawString).