my Mac is scrolling purple colour

This looks like a hardware issue.

You should get the MacBook Pro checked by an Authorised Apple Service Provider next to your place.

Use this link to find one:

Apple - Find Locations

Or give them a call by selecting the phone number for your region from this Apple page:

Contact Apple for support and service - Apple Support

You can also find out more about your service options on this page:

Mac Repair & Service - Apple Support

You're welcome 🙂