How can I make painted graphics in a JPanel scrollable?

Question

I am making an adaptation of a board game. The board will be drawn on a JPanel by overriding the paintComponent(Graphics g) method. The board can possibly be larger than the size of the JPanel it is drawn in, so I planned to use a JScrollPane to allow the user to scroll across the board to view it. As an example, I made the board a single large rectangle to see if I could get it to scroll across that, but to no avail. I have used JScrollPane successfully before but I cannot figure out why this case is any different from the way I previously used it.

Can anyone see why it is not working correctly?

Here is the code for the Game's JFrame:

public class GameFrame extends JFrame{

    JPanel playerDeckPanel, contentPane;
    JScrollPane gameScrollPane;

    BoardPanel boardPanel;

    public GameFrame(){
        super();

        SwingUtilities.invokeLater(new Runnable(){
                public void run(){
                    boardPanel = new BoardPanel();
                    playerDeckPanel = new JPanel();

                    boardPanel.setLayout(new GridLayout(1,1));
                    playerDeckPanel.setLayout(new CardLayout());

                    boardPanel.setSize(1000,1000);

                    gameScrollPane = new JScrollPane(boardPanel);
                    gameScrollPane.setPreferredSize(new Dimension(300,300));

                    contentPane = ((JPanel) getContentPane());

                    contentPane.setLayout(new GridLayout(1,2));
                    contentPane.add(gameScrollPane);
                    contentPane.add(playerDeckPanel);

                    setMinimumSize(new Dimension(800,600));
                }
            });
    }

    public static void main(String[] args){
        GameFrame gameFrame = new GameFrame();
        gameFrame.setVisible(true);
    }

    private class BoardPanel extends JPanel{

        public BoardPanel(){
            super();
        }

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

            g.setColor(Color.red);
            g.fillRect(100, 10, 700, 600);

            revalidate();
        }
    }
}

_{This is my first time posting a question, so let me know if you need additional information to solve this problem}

Answer 1

You need to setPreferredSize on BoardPanel, that seems to do the trick. Don't ask why ;-)

-@geert3