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I am preparing a separate PR that adds support for JXL with `jxl-oxide`,
which is unlikely to be added to the `image` crate anytime soon (more
context will be provided in that PR).
`jxl-oxide` makes use of the
[`array::each_mut`](https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_mut)
API which was stabilized in 1.77, which is the motivation for this MSRV
bump.
Rust 1.77 was officially released to stable on 21 March, 2024.
* Closes <https://github.com/emilk/egui/issues/4490>
* [x] I have followed the instructions in the PR template
---
Unfortunately, this PR contains a bunch of breaking changes because
`Context` no longer has one style, but two. I could try to add some of
the methods back if that's desired.
The most subtle change is probably that `style_mut` mutates both the
dark and the light style (which from the usage in egui itself felt like
the right choice but might be surprising to users).
I decided to deviate a bit from the data structure suggested in the
linked issue.
Instead of this:
```rust
pub theme: Theme, // Dark or Light
pub follow_system_theme: bool, // Change [`Self::theme`] based on `RawInput::system_theme`?
```
I decided to add a `ThemePreference` enum and track the current system
theme separately.
This has a couple of benefits:
* The user's theme choice is not magically overwritten on the next
frame.
* A widget for changing the theme preference only needs to know the
`ThemePreference` and not two values.
* Persisting the `theme_preference` is fine (as opposed to persisting
the `theme` field which may actually be the system theme).
The `small_toggle_button` currently only toggles between dark and light
(so you can never get back to following the system). I think it's easy
to improve on this in a follow-up PR :)
I made the function `pub(crate)` for now because it should eventually be
a method on `ThemePreference`, not `Theme`.
To showcase the new capabilities I added a new example that uses
different "accent" colors in dark and light mode:
<img
src="https://github.com/user-attachments/assets/0bf728c6-2720-47b0-a908-18bd250d15a6"
width="250" alt="A screenshot of egui's widget gallery demo in dark mode
using a purple accent color instead of the default blue accent">
<img
src="https://github.com/user-attachments/assets/e816b380-3e59-4f11-b841-8c20285988d6"
width="250" alt="A screenshot of egui's widget gallery demo in light
mode using a green accent color instead of the default blue accent">
---------
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Emil Ernerfeldt
TÖRÖK Attila
Cody Neiman
Tau Gärtli