This PR improves some fill performance issues I found with various Lottie animations.
I think the real issue comes down to the render performance of Path.addPath(). The performance issue happens in the Render thread and seems directly related to how large the animation is on-screen. Flutter might be caching pre-rendered textures and running out of memory.
I've changed how Path.addPath() is called and how the path is rendered for fill_content.dart and gradient_fill_content.dart.
Just as an example, the example/assets/Tests/bm.json animation gets ~60 fps with this fix, compared to 34-52 fps with the lottie-flutter 0.6.0 release. (This is on a Pixel 3 XL)
There are a couple of other changes:
- I fixed a bug with the casing of "weather" in pubspec.yaml. Without this fix, the examples don't build on Ubuntu Linux.
The debugging class MeanCalculator wasn't initializing its fields, causing a null pointer exception when debugging.
- I added antiAliasingSuggested to LottieDrawable to allow fill paints to be anti-aliased. It is off by default. It also provides some minor performance improvements without any noticeable loss in quality. It is only applied to fills right now.
- I added PathFactory to create Paths rather than just new-ing them. path_factory.dart allows you to switch out the normal Path creation with a debug logging implementation so you can see all of the Path calls that are performed during a frame. Just create a DebugPath in the factory rather than Path.
