I really like the UX of this. Very usable on a Wacom enabled android tablet.
Don't know if your spline editing mechanism (i.e. the ability to drag the line around from an aribtrary point rather than tweaking the individual handles) is something you came up with yourself or borrowed from elsewhere, but I really really like it.
Only thing I noticed is that touch scrolling doesn't work on the tree on the left. Otherwise it's very smooth.
Have you implemented any keyboard shortcuts?
Thanks, the curve dragging is surprisingly easy. I think a very old discussion in a Google forum have me the idea how to implement it. It even works with keeping the handle directions (pressing Shift while dragging).
That tree on the left is difficult to get right on all devices. It has to support click, touch to click, drag and drop, swipe scrolling, touch scrolling, etc., and all that while acting as if it holds hundreds of elements. There are still a few issues, for example swipe scrolling and some jankiness on iOS, but I have them on my list.
Keyboard shortcuts are implemented for non-mobile devices. If you open a menu on the menu bar, you can see them at the right in the menu items.
I'd be very interested in that discussion for one of my own projects, any chance you still have a link handy?
I was wrong, it was on Stackexchange. Stackexchange is full of true gems, and they really often have no or only very few upvotes, because nobody recognizes their value.