Custom Marking duration on line graph like in the images attached

[Narayan-Dhingra]

I need to present the data in android in the form of a Line graph and give the users a feature to be able to mark certain portions of the graph (starting and ending marker).

I am truly clueless about how am I gonna do this.

Any help or any link to the related blog will gonna help me a lot.

Much thanks in Advance _