This is an animation, drawn, in Pencil2D (MyPaint git branch, commit 5190.04c38ce7, more recent are less stable) with MyPaint brush first , but finished in MyPaint itself. The drawing is only a static image. It is then algorithmically animated in Lua, using a mesh, with LÖVE game engine.
Sadly mp4 format is not allowed, so this is a more heavy and far less good quality gif file, You can found the original mp4 animation and some other tests here
The picture finished with MyPaint and used for this animation: