Why is canvas a dependency of this module?

[IonicaBizau]

For debian based Linux distribution, canvas dependency installation requires install of cairo package

Actually, why is this required?

[robertleeplummerjr]

It is used for testing classification of different fonts to their letter. I can say after working in the unit tests that it isn't really done properly, as we only sample a very small area of the font, converted into an array, and then compared and classified.