java swing JEditorPane image

I have a frame which contains JEditorPane wrapped inside JScrollPane.

The problem is that when the frame is loaded JScrollPane is too small to show all JEditorPane content. But when I resize the frame or minimize/restore it JScrollPane gets normal.

I'm sure that is because JEditorPane contains an image, that has not already loaded.

The only way I have found is to revalidate frame in invokeLater method. It seems to me very odd and I want to find a way to do the same without invokeLater.

class MyFrame extends JFrame{

    MyFrame(){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(800, 800);

        JEditorPane editor = new JEditorPane();
        editor.setContentType("text/html");
        editor.setText("<p><img src=\"file:C:\\image.png\"></p>");

        JScrollPane scrollpane = new JScrollPane(editor);

        JPanel mainPanel = new JPanel();
        mainPanel.add(scrollpane);


        add(mainPanel,BorderLayout.CENTER);

        setLocationRelativeTo(null);
        setVisible(true);

        revalidate();   //  not working
        repaint();      //  not working

        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                revalidate();       //  OK
                repaint();          //  OK
            }
        });
    }
}