JTextArea - drawString in line with existing text

Question

The following code snippet paints a suggested auto complete string in a JTextArea:

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    if (suggestion != null && isSuggesting()) {
        final String selectedSuggestion = 
                suggestion.list.getSelectedValue().getValue().substring(
                        suggestion.subWord.length());
        g.setColor(Color.GRAY);
        final int position = getCaretPosition();
        Point location;
        try {
            location = modelToView(position).getLocation();
        } catch (BadLocationException e2) {
            e2.printStackTrace();
            return;
        }
        //TODO: 13 ???
        g.drawString(
                selectedSuggestion, 
                location.x, 
                13 + location.y);
    }
}

I use the magic number 13, which is great in my L&F:

But how do I calculate the right y position of the current line for general font size / L&F?

Answer 1

Maybe I'm missing something, but you already have the information you need:

Rectangle r = textArea.modelToView( textArea.getCaretPosition() );
int yOffset = r.y + r.height;

Answer 2

You can use the current font size for calculating the correct position.

Simply add the current font size to location.y like this:

g.drawString(selectedSuggestion, location.x, g.getFont().getSize() + location.y);

Edit: Using FontMetrics

    FontMetrics fm = getFontMetrics(g.getFont());
    int heightToAdd=(int)fm.getStringBounds("Sample Text", g).getHeight();
    g.drawString("Sample text", location.x, location.y+heightToAdd);

This was just a try with some random text.

Please refer the java docs here: Using FontMetrics