Smrf.NodeXL.Visualization.Wpf.EdgeDrawer.DrawSelfLoopAt C# (CSharp) Method

    DrawSelfLoopAt
    (
        DrawingContext oDrawingContext,
        GraphDrawingContext oGraphDrawingContext,
        Color oColor,
        Double dWidth,
        Point oSelfLoopEndpoint,
        RectangleEdge eFarthestGraphRectangleEdge,
        Boolean bDrawArrow
    )
    {
        Debug.Assert(oDrawingContext != null);
        Debug.Assert(oGraphDrawingContext != null);
        Debug.Assert(dWidth >= 0);
        AssertValid();

        // The self-loop is drawn as a circle.  Figure out the location of the
        // circle's center and the tip of the arrow, if there is an arrow.

        Double dCircleX, dCircleY, dArrowTipX, dArrowTipY, dArrowAngle;

        dCircleX = dArrowTipX = oSelfLoopEndpoint.X;
        dCircleY = dArrowTipY = oSelfLoopEndpoint.Y;
        Double dSelfLoopCircleDiameter = 2.0 * SelfLoopCircleRadius;
        dArrowAngle = 0;

        switch (eFarthestGraphRectangleEdge)
        {
            case RectangleEdge.Top:

                dCircleY -= SelfLoopCircleRadius;
                dArrowTipY -= dSelfLoopCircleDiameter;
                break;

            case RectangleEdge.Left:

                dCircleX -= SelfLoopCircleRadius;
                dArrowTipX -= dSelfLoopCircleDiameter;
                dArrowAngle = Math.PI / 2.0;  // (90 degrees.)
                break;

            case RectangleEdge.Right:

                dCircleX += SelfLoopCircleRadius;
                dArrowTipX += dSelfLoopCircleDiameter;
                dArrowAngle = -Math.PI / 2.0;  // (-90 degrees.)
                break;

            case RectangleEdge.Bottom:

                dCircleY += SelfLoopCircleRadius;
                dArrowTipY += dSelfLoopCircleDiameter;
                dArrowAngle = Math.PI;  // (180 degrees.)
                break;

            default:

                Debug.Assert(false);
                break;
        }

        oDrawingContext.DrawEllipse(null, GetPen(oColor, dWidth),
            new Point(dCircleX, dCircleY), SelfLoopCircleRadius,
            SelfLoopCircleRadius);

        if (bDrawArrow)
        {
            // Rotate the arrow slightly to adjust to the circular shape of the
            // edge connected to it.

            dArrowAngle += Math.PI / 13.0;

            DrawArrow(oDrawingContext, new Point(dArrowTipX, dArrowTipY),
                dArrowAngle, oColor, dWidth);
        }
    }