public override void Apply(CanvasItem item, Context cr)
{
int steps = ShadowSize;
double opacity_step = ShadowOpacity / ShadowSize;
var color = new Color(0, 0, 0);
double width = Math.Round(item.Allocation.Width);
double height = Math.Round(item.Allocation.Height);
if (Fill != null)
{
cr.Rectangle(ShadowSize, ShadowSize, width - ShadowSize * 2, height - ShadowSize * 2);
Fill.Apply(cr);
cr.Fill();
}
cr.LineWidth = 1.0;
for (int i = 0; i < steps; i++)
{
CairoExtensions.RoundedRectangle(cr,
i + 0.5,
i + 0.5,
(width - 2 * i) - 1,
(height - 2 * i) - 1,
steps - i);
color.A = opacity_step * (i + 1);
cr.SetSourceColor(color);
cr.Stroke();
}
}