When painting a scatter plot we sometimes want to paint hundreds of thousands of points (filled circles) on screen every frame.
In this PR the font texture atlas is pre-populated with some filled circled of various radii. These are then used when painting (small) filled circled, which means A LOT less triangles and vertices are generated for them.
In a new benchmark we can see a 10x speedup in circle tessellation, but the the real benefit comes in the painting of these circles: since we generate a lot less vertices, the backend painter has less to do.
In a real-life scenario with a lot of things being painted (including around 100k points) I saw tessellation go from 35ms -> 7ms and painting go from 45ms -> 1ms. This means the total frame time went from 80ms to 8ms, or a 10x speedup.
* Rename AlphaImage to FontImage to discourage any other use for it
* Encode FontImage as f32 and postpone the alpha correction
* Interpret alpha coverage in a new, making dark text darker, improving contrast in bright mode
* egui_web: use tracing crate
* egui_glow: use tracing crate
* Log at the debug level
* egui_demo_app: enable tracing to log to stdout
* Use tracing in egui-winit
* Add opt-in tracing support to egui
* Refactor text layout: don't need &Fonts in all functions
* Replace indexing in Fonts with member function
* Wrap Fonts in a Mutex
* Remove mutex for Font::glyph_info_cache
* Remove RwLock around Font::characters
* Put FontsImpl and GalleyCache behind the same Mutex
* Round font sizes to whole pixels before deduplicating them
* Make TextStyle !Copy
* Implement user-named TextStyle:s
* round font size earlier
* Cache fonts based on family and size
* Move TextStyle into egui and Style
* Remove body_text_style
* Query graphics about max texture size and use that as font atlas size
* Recreate texture atlas when it is getting full
* Move texture allocation into epaint/egui proper
* Add TextureHandle
* egui_glow: cast using bytemuck instead of unsafe code
* Optimize glium painter
* Optimize WebGL
* Add example of loading an image from file
