Hi Rajesh,

We made a basic sample that shows how this can be achieved. You can download it from here:
https://mindfusion.eu/_samples/CustomLinkSample.zip

The link is a custom class, deriving from DiagramLink and all the custom drawing (circle and colored lines) is done in the UpdateVisuals override.

The custom link has a Position dependency property that lets you adjust the relative position of the circle on the line.

Regards,
Lyubo

Hi Rajesh,

We've updated the sample to support also cascading and bezier link styles.

You can download it from here:
https://mindfusion.eu/_samples/CustomLinkSample.zip

To find the circle position on a bezier curve relatively easy, we first approximate the curve to a series of straight lines, and then apply the same logic as with other link styles.
Alternatively, you could use de Casteljau's algorithm - http://en.wikipedia.org/wiki/De_Casteljau%27s_algorithm to split the curve into two in order to find circle's position.

I hope this helps.

Regards,
Lyubo