egui/crates/egui_extras
Lucas Meurer 6eb7bb6e08
Add `AtomLayout`, abstracing layouting within widgets (#5830)
Today each widget does its own custom layout, which has some drawbacks:
- not very flexible
- you can add an `Image` to `Button` but it will always be shown on the
left side
  - you can't add a `Image` to a e.g. a `SelectableLabel`
- a lot of duplicated code

This PR introduces `Atoms` and `AtomLayout` which abstracts over "widget
content" and layout within widgets, so it'd be possible to add images /
text / custom rendering (for e.g. the checkbox) to any widget.

A simple custom button implementation is now as easy as this:
```rs
pub struct ALButton<'a> {
    al: AtomicLayout<'a>,
}

impl<'a> ALButton<'a> {
    pub fn new(content: impl IntoAtomics) -> Self {
        Self { al: content.into_atomics() }
    }
}

impl<'a> Widget for ALButton<'a> {
    fn ui(mut self, ui: &mut Ui) -> Response {
        let response = ui.ctx().read_response(ui.next_auto_id());

        let visuals = response.map_or(&ui.style().visuals.widgets.inactive, |response| {
            ui.style().interact(&response)
        });

        self.al.frame = self
            .al
            .frame
            .inner_margin(ui.style().spacing.button_padding)
            .fill(visuals.bg_fill)
            .stroke(visuals.bg_stroke)
            .corner_radius(visuals.corner_radius);

        self.al.show(ui)
    }
}

```

The initial implementation only does very basic layout, just enough to
be able to implement most current egui widgets, so:
- only horizontal layout
- everything is centered
- a single item may grow/shrink based on the available space
- everything can be contained in a Frame


There is a trait `IntoAtoms` that conveniently allows you to construct
`Atoms` from a tuple
```
   ui.button((Image::new("image.png"), "Click me!"))
```
to get a button with image and text.


This PR reimplements three egui widgets based on the new AtomLayout:
 - Button
   - matches the old button pixel-by-pixel
- Button with image is now [properly
aligned](https://github.com/emilk/egui/pull/5830/files#diff-962ce2c68ab50724b01c6b64c683c4067edd9b79fcdcb39a6071021e33ebe772)
in justified layouts
   - selected button style now matches SelecatbleLabel look
- For some reason the DragValue text seems shifted by a pixel almost
everywhere, but I think it's more centered now, yay?
 - Checkbox
- basically pixel-perfect but apparently the check mesh is very slightly
different so I had to update the snapshot
   - somehow needs a bit more space in some snapshot tests?
 - RadioButton
   - pixel-perfect
   - somehow needs a bit more space in some snapshot tests?

I plan on updating TextEdit based on AtomLayout in a separate PR (so
you could use it to add a icon within the textedit frame).
2025-06-13 09:39:52 +02:00
..
src Add `AtomLayout`, abstracing layouting within widgets (#5830) 2025-06-13 09:39:52 +02:00
CHANGELOG.md Release 0.31.1 - text_edit and kittest fixes 2025-03-05 08:37:34 +01:00
Cargo.toml Include test windows in `egui_demo_lib` snapshot tests (#7070) 2025-05-21 17:44:27 +02:00
README.md Update `image` crate to 0.25 (#4160) 2024-05-13 13:35:15 +02:00

README.md

egui_extras

Latest version Documentation unsafe forbidden MIT Apache

This is a crate that adds some features on top top of egui. This crate is for experimental features, and features that require big dependencies that do not belong in egui.

Images

One thing egui_extras is commonly used for is to install image loaders for egui:

egui_extras = { version = "*", features = ["all_loaders"] }
image = { version = "0.25", features = ["jpeg", "png"] } # Add the types you want support for
egui_extras::install_image_loaders(egui_ctx);