When I use drag feature, then the circles on the polygon edge has the same style. For example, this OpenLayers site.
I need to change it, I mean they need to be a different color.
What is their (cycles) style attribute?
You should use
At result we have the following style:
The approach outlined by @drnextgis is the correct one to follow. However, be aware that there is currently a bug in OpenLayers (as of version 2.11) that means if you add a unique values renderer to the
If you encounter this please look at my question for details of how to work around it.