Great! Rendering client-side using JS graphics libraries will be more elegant and is not as kludgy 
However, that means Discourse will have to store all the intermediate vote states.
The reason I went for the RMagick suggestion is so that Discourse doesn’t have to store voting states over time, as seems to be the case with the current polls looking at the poll attribute.
It will only have to store the latest vote, and the historical votes can be “stored” by just time-stamped previous ImageMagick renders.