Smrf.NodeXL.Visualization.Wpf.VertexDrawingHistory.GetEdgeEndpointOnRectangle C# (CSharp) Method

    GetEdgeEndpointOnRectangle
    (
        Point oVertexALocation,
        Rect oVertexARectangle,
        Point oVertexBLocation,
        out Point oEdgeEndpoint
    )
    {
        AssertValid();

        if (oVertexALocation == oVertexBLocation)
        {
            oEdgeEndpoint = oVertexALocation;

            return;
        }

        Double dVertexAX = oVertexALocation.X;
        Double dVertexAY = oVertexALocation.Y;

        Double dVertexBX = oVertexBLocation.X;
        Double dVertexBY = oVertexBLocation.Y;

        Double dHalfVertexARectangleWidth = oVertexARectangle.Width / 2.0;
        Double dHalfVertexARectangleHeight = oVertexARectangle.Height / 2.0;

        // Get the angle between vertex A and vertex B.

        Double dEdgeAngle = WpfGraphicsUtil.GetAngleBetweenPointsRadians(
            oVertexALocation, oVertexBLocation);

        // Get the angle that defines the aspect ratio of vertex A's rectangle.

        Double dAspectAngle = Math.Atan2(
            dHalfVertexARectangleHeight, dHalfVertexARectangleWidth);

        if (dEdgeAngle >= -dAspectAngle && dEdgeAngle < dAspectAngle)
        {
            // For a square, this is -45 degrees to 45 degrees.

            Debug.Assert(dVertexBX != dVertexAX);

            oEdgeEndpoint = new Point(

                dVertexAX + dHalfVertexARectangleWidth,

                dVertexAY + dHalfVertexARectangleWidth *
                    ( (dVertexBY - dVertexAY) / (dVertexBX - dVertexAX) )
                );

            return;
        }

        if (dEdgeAngle >= dAspectAngle && dEdgeAngle < Math.PI - dAspectAngle)
        {
            // For a square, this is 45 degrees to 135 degrees.

            Debug.Assert(dVertexBY != dVertexAY);

            oEdgeEndpoint = new Point(

                dVertexAX + dHalfVertexARectangleHeight *
                    ( (dVertexBX - dVertexAX) / (dVertexAY - dVertexBY) ),

                dVertexAY - dHalfVertexARectangleHeight
                );

                return;
        }

        if (dEdgeAngle < -dAspectAngle && dEdgeAngle >= -Math.PI + dAspectAngle)
        {
            // For a square, this is -45 degrees to -135 degrees.

            Debug.Assert(dVertexBY != dVertexAY);

            oEdgeEndpoint = new Point(

                dVertexAX + dHalfVertexARectangleHeight *
                    ( (dVertexBX - dVertexAX) / (dVertexBY - dVertexAY) ),

                dVertexAY + dHalfVertexARectangleHeight
                );

            return;
        }

        // For a square, this is 135 degrees to 180 degrees and -135 degrees to
        // -180 degrees.

        Debug.Assert(dVertexAX != dVertexBX);

        oEdgeEndpoint = new Point(

            dVertexAX - dHalfVertexARectangleWidth,

            dVertexAY + dHalfVertexARectangleWidth *
                ( (dVertexBY - dVertexAY) / (dVertexAX - dVertexBX) )
            );
    }