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

    DrawStraightLabel
    (
        DrawingContext oDrawingContext,
        GraphDrawingContext oGraphDrawingContext,
        FormattedText oFormattedText,
        Point oEdgeEndpoint1,
        Point oEdgeEndpoint2,
        Double dLabelOriginAsFractionOfEdgeLength,
        Double dEdgeLength,
        Double dBufferWidth,
        Color oTranslucentRectangleColor
    )
    {
        Debug.Assert(oDrawingContext != null);
        Debug.Assert(oGraphDrawingContext != null);
        Debug.Assert(oFormattedText != null);
        Debug.Assert(dLabelOriginAsFractionOfEdgeLength >= 0);
        Debug.Assert(dEdgeLength >= 0);
        Debug.Assert(dBufferWidth >= 0);
        AssertValid();

        if (oEdgeEndpoint2.X < oEdgeEndpoint1.X)
        {
            // Don't let text be drawn upside-down.

            WpfGraphicsUtil.SwapPoints(ref oEdgeEndpoint1, ref oEdgeEndpoint2);
        }

        // To avoid trigonometric calculations, use a RotateTransform to make
        // the edge look as if it is horizontal, with oEdgeEndpoint2 to the
        // right of oEdgeEndpoint1.

        Double dEdgeAngleDegrees = MathUtil.RadiansToDegrees(
            WpfGraphicsUtil.GetAngleBetweenPointsRadians(
                oEdgeEndpoint1, oEdgeEndpoint2) );

        RotateTransform oRotateTransform = new RotateTransform(
            dEdgeAngleDegrees, oEdgeEndpoint1.X, oEdgeEndpoint1.Y);

        oRotateTransform.Angle = -dEdgeAngleDegrees;
        oDrawingContext.PushTransform(oRotateTransform);

        Double dTextWidth = oFormattedText.Width;
        Double dEdgeLengthMinusBuffers = dEdgeLength - 2 * dBufferWidth;

        Point oLabelOrigin = oEdgeEndpoint1;

        // The text should be vertically centered on the edge.

        oLabelOrigin.Offset(dLabelOriginAsFractionOfEdgeLength * dEdgeLength,
            -oFormattedText.Height / 2.0);

        // Determine where to draw a translucent rectangle behind the text.
        // The translucent rectangle serves to obscure, but not completely
        // hide, the underlying edge.

        Rect oTranslucentRectangle;

        if (dTextWidth > dEdgeLengthMinusBuffers)
        {
            // The translucent rectangle should be the same width as the text.

            oTranslucentRectangle = new Rect( oLabelOrigin,
                new Size(dEdgeLengthMinusBuffers, oFormattedText.Height) );
        }
        else
        {
            // The label is centered along the edge's length.

            // The translucent rectangle should extend between zero and one
            // buffer units beyond the ends of the text.  This provides a
            // margin between the text and the unobscured edge, if there is
            // enough space.

            oTranslucentRectangle = new Rect( oLabelOrigin,

                new Size(
                    Math.Min(dTextWidth + 2 * dBufferWidth,
                        dEdgeLengthMinusBuffers),

                    oFormattedText.Height)
                );

            oTranslucentRectangle.Offset(-dBufferWidth, 0);
        }

        DrawTranslucentRectangle(oDrawingContext, oTranslucentRectangle,
            oTranslucentRectangleColor);

        oDrawingContext.DrawText(oFormattedText, oLabelOrigin);

        oDrawingContext.Pop();
    }