9-Patch is a C2 default plugin , is hard to explain so better try and see how they works.
The problem about this plugin as i said is that not allow animation/frames and not allow rotations, so the idea is use a Sprite plugin instead with a shader that allos the same option to have the ability to ass frames/animation and rotations.
Basically 9-patch get the image you add and rip in 9 parts like:
In the plugin properties you set how this image is Tile-based with pixel width/height in left/right/top/bottom and if they will work as tiles, stretch or how. Is hard to explain better see the 9-Patch official manual here:
So the idea is that, in case is possible, do a shader that can do the shame for a sprite image.