protected override void PaintImp(PaintVisitor p)
{
// load image iff it is in visible rectangle
//1. single image can't be splited
#if DEBUG
p.dbugEnterNewContext(this, PaintVisitor.PaintVisitorContextName.Init);
#endif
Paint(p, new RectangleF(0, 0, this.VisualWidth, this.VisualHeight));
#if DEBUG
p.dbugExitContext();
#endif
}