It would be nice to have this feature added to the drawing tools. Below are a couple screenshots. These are taken from the traderview website and their charting software.
Screen Shot 2017-10-14 at 11.27.34 pm.png (68.94 KiB) Viewed 22212 times
Screen Shot 2017-10-14 at 11.28.09 pm.png (72.68 KiB) Viewed 22212 times