public void paintGraph(Graphics gr, DrawAreaInterface da) {
if (!isVisible()) return;
Color ca = gr.getColor();
Graphics2D g = (Graphics2D) gr;
Stroke strokeOld = g.getStroke();
g.setColor(getColor());
g.setStroke(AbstractGraph.getStroke(da.getStroke(), getLineStyle()));
evalFunction();
paint(g, da);
g.setColor(ca);
g.setStroke(strokeOld);
} // paintGraph