diff --git a/src/widgets.rs b/src/widgets.rs index e0a56a57..f5345332 100644 --- a/src/widgets.rs +++ b/src/widgets.rs @@ -245,6 +245,11 @@ pub trait StatefulWidget { /// provided. This is a convenience approach to make it easier to attach child widgets to parent /// widgets. It allows you to render an optional widget by reference. /// +/// A blanket [implementation of `WidgetRef` for `Fn(Rect, &mut +/// Buffer)`](WidgetRef#impl-WidgetRef-for-F) is provided. This allows you to treat any function or +/// closure that takes a `Rect` and a mutable reference to a `Buffer` as a widget in situations +/// where you don't want to create a new type for a widget. +/// /// # Examples /// /// ```rust @@ -304,13 +309,40 @@ pub trait WidgetRef { fn render_ref(&self, area: Rect, buf: &mut Buffer); } -/// This allows you to render a widget by reference. +// /// This allows you to render a widget by reference. impl Widget for &W { fn render(self, area: Rect, buf: &mut Buffer) { self.render_ref(area, buf); } } +/// A blanket implementation of `WidgetRef` for `Fn(Rect, &mut Buffer)`. +/// +/// This allows you to treat any function that takes a `Rect` and a mutable reference to a `Buffer` +/// as a widget in situations where you don't want to create a new type for a widget. +/// +/// # Examples +/// +/// ```rust +/// use ratatui::{prelude::*, widgets::*}; +/// fn hello(area: Rect, buf: &mut Buffer) { +/// Line::raw("Hello").render(area, buf); +/// } +/// +/// fn draw(mut frame: Frame) { +/// frame.render_widget(&hello, frame.size()); +/// frame.render_widget_ref(hello, frame.size()); +/// } +/// ``` +impl WidgetRef for F +where + F: Fn(Rect, &mut Buffer), +{ + fn render_ref(&self, area: Rect, buf: &mut Buffer) { + self(area, buf); + } +} + /// A blanket implementation of `WidgetExt` for `Option` where `W` implements `WidgetRef`. /// /// This is a convenience implementation that makes it easy to attach child widgets to parent @@ -695,4 +727,42 @@ mod tests { assert_eq!(buf, Buffer::with_lines(["hello world "])); } } + + mod function_widget { + use super::*; + + fn widget_function(area: Rect, buf: &mut Buffer) { + "Hello".render(area, buf); + } + + #[rstest] + fn render(mut buf: Buffer) { + widget_function.render(buf.area, &mut buf); + assert_eq!(buf, Buffer::with_lines(["Hello "])); + } + + #[rstest] + fn render_ref(mut buf: Buffer) { + widget_function.render_ref(buf.area, &mut buf); + assert_eq!(buf, Buffer::with_lines(["Hello "])); + } + + #[rstest] + fn render_closure(mut buf: Buffer) { + let widget = |area: Rect, buf: &mut Buffer| { + "Hello".render(area, buf); + }; + widget.render(buf.area, &mut buf); + assert_eq!(buf, Buffer::with_lines(["Hello "])); + } + + #[rstest] + fn render_closure_ref(mut buf: Buffer) { + let widget = |area: Rect, buf: &mut Buffer| { + "Hello".render(area, buf); + }; + widget.render_ref(buf.area, &mut buf); + assert_eq!(buf, Buffer::with_lines(["Hello "])); + } + } }