iced_optional_element_shim/
lib.rs

1use iced::{advanced::{layout, mouse, renderer, widget::Tree, Layout, Widget}, Element, Length, Rectangle, Renderer, Size, Theme};
2
3/// Works to convert `Option<T>` to `Element<'a, Message, Theme, Renderer>`
4///
5/// iced versions after 0.13.1 have a `From` impl so they don't need this.
6///
7/// Usage:
8///
9///     use iced_optional_element_shim::to_elem;
10///
11///     fn view(&self) -> Element<'a, Message> {
12///         column!(
13///            text("Example header"),
14///
15///            if true {
16///                to_elem(Some(text("this element will display")))
17///            } else {
18///                to_elem::<Message, iced::widget::Text>(None)
19///            },
20///
21///            if false {
22///                to_elem(Some(text("this element will not display")))
23///            } else {
24///                to_elem::<Message, iced::widget::Text>(None)
25///            },
26///
27///            text("footer"),
28///        )
29///     }
30///
31pub fn to_elem<'a, Message, T: Into<Element<'a, Message, Theme, Renderer>>>(element: Option<T>) -> Element<'a, Message, Theme, Renderer> {
32    struct Void;
33
34    impl<Message, Theme, Renderer> Widget<Message, Theme, Renderer> for Void
35    where Renderer: iced::advanced::Renderer
36    {
37        fn size(&self) -> Size<Length> {
38            Size {
39                width: Length::Fixed(0.0),
40                height: Length::Fixed(0.0),
41            }
42        }
43
44        fn layout(
45            &self,
46            _tree: &mut Tree,
47            _renderer: &Renderer,
48            _limits: &layout::Limits,
49        ) -> layout::Node {
50            layout::Node::new(Size::ZERO)
51        }
52
53        fn draw(
54            &self,
55            _tree: &Tree,
56            _renderer: &mut Renderer,
57            _theme: &Theme,
58            _style: &renderer::Style,
59            _layout: Layout<'_>,
60            _cursor: mouse::Cursor,
61            _viewport: &Rectangle,
62        ) {
63        }
64    }
65
66    element.map(T::into).unwrap_or_else(|| Element::new(Void))
67}
68
69// #[cfg(test)]
70// mod tests {
71//     use super::*;
72
73//     #[test]
74//     fn it_works() {
75//         let result = add(2, 2);
76//         assert_eq!(result, 4);
77//     }
78// }
iced_optional_element_shim/lib.rs

iced_optional_element_shim/
lib.rs
