* Re-implement PaintCallbacks With Support for WGPU
This makes breaking changes to the PaintCallback system, but makes it
flexible enough to support both the WGPU and glow backends with custom
rendering.
Also adds a WGPU equivalent to the glow demo for custom painting.
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.
This allows line breaks after any kana, unless they are immediately followed by a gyōtō kinsoku character, in which case the line may not break at that point.
Also pedantically renamed is_chinese to is_cjk_ideograph as is_chinese will also cause line breaks on Japanese kanji.
* Update to rust 1.60.0
* Rename the feature `convert_bytemuck` to `bytemuck`
* Rename the feature `serialize` to `serde`.
* Make use of the "weak dependency" cargo feature
* Set rust-version = "1.60" for all crates
* egui_glow: clipboard, links, persistence & winit are now opt-in features
The purpose of this is to expose `frame.storage()` and `frame.storage_mut()` so users can save/load app state from the `App::update` function, without having to add another parameter to that function.
Changes:
* Added `Frame::storage()` and `Frame::storage_mut()`
* `App::update` now takes a `&mut Frame` rather than just `&Frame`
* `Frame` is no longer `Clone` or `Sync` (doesn't have to be since https://github.com/emilk/egui/pull/1366)
* 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
The epaint tessellator uses "feathering" to accomplish anti-aliasing. This PS allows you to control the feathering size, i.e. how blurry the edges of epaint shapes are.
This changes the interface of Tessellator slightly, and renames some options in TessellationOptions.
