Try using canvas width="200" height="200"

Change the code so that it uses requestAnimation frame
Also make a list of animation objects which have a finite lifetime and a processing function
and a generic draw routine where the context tells it if things need to be drawn or not.

This should greatly simplify the code and its readability.

Just showing a graph isn't enough - we haven't yet dealt with tying it in to other systems, dismissing the pie chart in an animated way, or animating it, or showing the real data tied to it.
What about a legend?
What about a title?
By encompassing a more rich example, we might get an idea of what's really left to do.

Before the context is executed, allow a callback to manipulate the context prior to execution.

• this has already been done, but not very advanced - more use cases required - probably will evolve over time.

AnimPie.makePie([255,1], 'c');

AnimPie.makePie([12, 12, 12, 12, 12, 12], 'c');

AnimPie.makePie([1,2,3,4,5,6], 'c');

The code intends that arc 1 rotates clockwise, 2 anticlockwise, 3 clockwise ad infin item.
Yet demonstrably arc 1 is clockwise, 2&3 anti clockwise 4&5 clockwise!