public void Refresh()
{
var g = panel1.CreateGraphics();
g.Clear(panel1.BackColor);
foreach (var item in shapes)
{
if (item is rectangle)
{
rectangle r = (rectangle)item;
r.Draw(g);
}
else if (item is circle)
{
circle c = (circle)item;
c.Draw(g);
}
else if (item is ellipse)
{
ellipse e = (ellipse)item;
e.Draw(g);
}
else if (item is line)
{
line l = (line)item;
l.Draw(g);
}
else if (item is polygon)
{
polygon p = (polygon)item;
p.Draw(g);
}
}
}
