You Do Need power plug adapter while traveling from Canary Islands to Sri Lanka.

Here is Why You Need An Adapter

The outlet and plug type used in Sri Lanka is G and in Canary Islands are C, E and F. This is how they look like.

Canary Islands

In Canary Islands, outlets of type C, E and F are in use.

Type C

Type E

Type F

Sri Lanka

In Sri Lanka, outlets of type G are in use.

Type G