egui/crates/egui_demo_app
Emil Ernerfeldt 3f731ec794
Fix semi-transparent colors appearing too bright (#5824)
The bug was in `Color32::from_rgba_unmultiplied` and by extension
affects:

* `Color32::from_rgba_unmultiplied`
* `hex_color!`
* `HexColor`
* `ColorImage::from_rgba_unmultiplied`
* All images with transparency (png, webp, …)
* `Color32::from_white_alpha`

The bug caused translucent colors to appear too bright.

## More
Color is hard.

When I started out egui I thought "linear space is objectively better,
for everything!" and then I've been slowly walking that back for various
reasons:

* sRGB textures not available everywhere
* gamma-space is more _perceptually_ even, so it makes sense to use for
anti-aliasing
* other applications do everything in gamma space, so that's what people
expect (this PR)

Similarly, pre-multiplied alpha _makes sense_ for blending colors. It
also enables additive colors, which is nice. But it does complicate
things. Especially when mixed with sRGB/gamma (As @karhu [points
out](https://github.com/emilk/egui/pull/5824#issuecomment-2738099254)).

## Related
* Closes https://github.com/emilk/egui/issues/5751
* Closes https://github.com/emilk/egui/issues/5771 ? (probably; hard to
tell without a repro)
* But not https://github.com/emilk/egui/issues/5810

## TODO
* [x] I broke the RGBA u8 color picker. Fix it

---------

Co-authored-by: Andreas Reich <andreas@rerun.io>
2025-03-21 10:45:25 +01:00
..
src Add `Ui::close` and `Response::should_close` (#5729) 2025-02-20 17:59:29 +01:00
tests Fix semi-transparent colors appearing too bright (#5824) 2025-03-21 10:45:25 +01:00
Cargo.toml Bump accesskit to 0.18 and make it a workspace dependency (#5783) 2025-03-20 11:00:12 +01:00
README.md Rename `sh/` folder to `scripts/` 2023-04-18 17:10:52 +02:00

README.md

egui demo app

This app demonstrates egui and eframe.

View the demo app online at https://egui.rs.

Run it locally with cargo run --release -p egui_demo_app.

egui_demo_app can be compiled to WASM and viewed in a browser locally with:

./scripts/start_server.sh &
./scripts/build_demo_web.sh --open

egui_demo_app uses egui_demo_lib.

Running with wgpu backend

(cd egui_demo_app && cargo r --features wgpu)