Rendering Blurriness Due to Default Cairo Library Grid System

[jamesbriggs]

All of the charts produced with Chart::Clicker have blurry lines and text.

The Cairo FAQ has an entry describing the problem and workarounds for it.
https://www.cairographics.org/FAQ/#sharp_lines

"Either way, you can avoid the issue by using an even-integer line width, (note that the default line width in cairo is 2.0). A line drawn this way will still affect just as many pixels, but they will be affected at full intensity.

Otherwise, if you really want to light up a single row of pixels at full intensity, you can do that by adjusting the endpoints by 0.5 in the appropriate direction. "