Diff of Circle

• The added line is THIS COLOR.
• The deleted line is THIS COLOR.
• Go to Circle.

[[Rasterize]]
[[Rasterize]] > [[Circle]]

- Midpoint circle algorithm
--  https://en.wikipedia.org/wiki/Midpoint_circle_algorithm

*. [#a27c0994]

- 三角関数を使わずに円を描く
--  https://qiita.com/nak435/items/5f55993f1842f8495dbf
---   https://github.com/adafruit/Adafruit-GFX-Library/blob/master/Adafruit_GFX.cpp