Don't be fooled by the graphic.
Protractor is a measuring tool. Measuring tools must have high accuracy and high precision. This app follows the same principle.
No documentation provided, only 2 buttons and 3 slider controls. Nothing else.
Angle is rounded to the 6 decimal places. (3 on full screen mode)
Simple graphic made it possible to see through white paper (Please adjust your screen brightness to the maximum setting)