This change allows `layouter` to use the `TextBuffer` instead of `&str`
in the closure. It is necessary when layout decisions depend on more
than just the raw string content, such as metadata stored in the
concrete type implementing `TextBuffer`.
In [our use case](https://github.com/damus-io/notedeck/pull/723), we
needed this to support mention highlighting when a user selects a
mention. Since mentions can contain spaces, determining mention
boundaries from the `&str` alone is impossible. Instead, we use the
`TextBuffer` implementation to retrieve the correct bounds.
See the video below for a demonstration:
https://github.com/user-attachments/assets/3cba2906-5546-4b52-b728-1da9c56a83e1
# Breaking change
This PR introduces a breaking change to the `layouter` function in
`TextEdit`.
Previous API:
```rust
pub fn layouter(mut self, layouter: &'t mut dyn FnMut(&Ui, &str, f32) -> Arc<Galley>) -> Self
```
New API:
```rust
pub fn layouter(mut self, layouter: &'t mut dyn FnMut(&Ui, &dyn TextBuffer, f32) -> Arc<Galley>) -> Self
```
## Impact on Existing Code
• Any existing usage of `layouter` will **no longer compile**.
• Callers must update their closures to use `&dyn TextBuffer` instead of
`&str`.
## Migration Guide
Before:
```rust
let mut layouter = |ui: &Ui, text: &str, wrap_width: f32| {
let layout_job = my_highlighter(text);
layout_job.wrap.max_width = wrap_width;
ui.fonts(|f| f.layout_job(layout_job))
};
```
After:
```rust
let mut layouter = |ui: &Ui, text: &dyn TextBuffer, wrap_width: f32| {
let layout_job = my_highlighter(text.as_str());
layout_job.wrap.max_width = wrap_width;
ui.fonts(|f| f.layout_job(layout_job))
};
```
---
* There is not an issue for this change.
* [x] I have followed the instructions in the PR template
Signed-off-by: kernelkind <kernelkind@gmail.com>
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