I just checked the website and saw that you added brush smoothing to CherryBrush. Yay! I've only been playing with it for a few minutes, but so far it works really well. I've been wanting to do some simple hand drawn animation for a long time (I primarily do 3D), and now I have no excuse.
Thank you for Cherry Brush, it's better than Digicel Flipbook lite, which I paid $40 for. Flipbook with unlimited levels is $60 more. I put up a little tutorial on animation- terrymorgan.net/anim_cherry_brush.zip
Frankly...I'm mildly speechless. Last year I've written a small 2d paint/animation app for a few days, never finished it, but it had kind of the same soul as this. Except, I think you have far more what it takes to make a brilliant little or even big app.
Timeline with keyframes would rock. You could implement it into the layer window. Basically you'd be able to add a frame to a specific time along the timeline, maybe even setting modes for it, too, like replace, add, subtract, etc.... You could also make the frames duration optional, so you could drag in or out the length it would hold in time. Then the ability to move such keyframes back and forth across the timeline, delete, dublicate.
Multiselect frames across time and potentially across layers would be the final stroke, I think. If you had all that, you'd be incredibly close to an eyewateringly beautiful animation app!
Congratulations already to a fine, fine piece of work! It really feels like you're having some real fun with this and I can perfectly relate, if that's the case. I do know the pains involved as well, but it's a unique kind of pleasure to explore this sort of creation.
Yeah, the animation interface is very primitive. I added it as an after-thought when a guy requested animation and I realized it would be possible without too much additional effort on my part.
My other project 'animape' has some more sophisticated animation/keyframing functionality, but unfortunately the two are pretty much incompatible since you can't save PNG images with transparency in CherryBrush, and obviously you can't paint in animape... Maybe in a few years I'll make the ultimate application as a blend between the two