public PreviewRenderer(Preview preview, Layout layout, Pixmap pixmap,
GC gc)
{
_pixmap = pixmap;
_gc = gc;
_pw = preview.WidthRequest;
_ph = preview.HeightRequest;
_zoom = layout.Boundaries(_pw, _ph, out _offx, out _offy);
}
void Add(Layout layout)
{
_set.Add(layout);
}