Question

I’ve got a following problem. I want to draw lines over BufferedImage, but they don’t show up. If i don’t load the image, they will show. What is the problem? Here is my code:

@Override
    public void paintComponent(Graphics g) {
        prepareImage();
        g.drawImage(buffer, 0, 0, null);
        g.dispose();
    }
    private void prepareImage() {
        Graphics g = buffer.createGraphics();
        g.drawImage(mapImage, 0, 0, null);
        g.setColor(Color.RED);
        for (Line line : lines)
            g.drawLine(line.x1, line.y1, line.x2, line.y2);
        lines.clear();
        g.dispose();
    }

Thanks for help.

Answer 1

I see two issues in your code:

1. You shouldn’t be calling g.dispose() in paintComponent
2. Since you clear the lines collection, the next time paintComponent is called (and you have no control on that), no line will be drawn.