The aim of this patch is to increase options for users of Krita, and to increase interchangeability with other application (A few software use Reflect Blending Mode). Formulas are found in Pegtop Delphi site - http://www.pegtop.net/delphi/articles/blendmodes/quadratic.htm
Differentials
- https://phabricator.kde.org/differential/diff/35689/
For the Pegtop part, all seem to work just fine. - https://forum.kde.org/viewtopic.php?f=288&p=399595#p399595
However, there does seem to be a issue with Paint.NET blend mode documentation test images - https://www.getpaint.net/doc/latest/BlendModes.html , and it's not something that can be solved by conditional ifzero, then zero or ifunit, then unit.
- https://i.imgur.com/JT9AXCL.png
Note that ugly black stain over that image. Yeah, that's the issue. There's also ZX Spectrum bug, but that's a bug that can be found with Color Dodge and Parallel Blending Mode - https://bugs.kde.org/show_bug.cgi?id=395036