tek/engine/src/content.rs

use crate::*;
/// Build a [Render]able out of other [Render]ables,
/// then apply optional custom render/layout on top.
pub trait Content<E: Output>: Send + Sync + Sized {
    fn content (&self) -> impl Render<E> { () }
    fn layout (&self, area: E::Area) -> E::Area { self.content().layout(area) }
    fn render (&self, output: &mut E) { self.content().render(output) }
}
impl<E: Output, C: Content<E>> Content<E> for &C {
    fn content (&self) -> impl Render<E> { (*self).content() }
    fn layout (&self, area: E::Area) -> E::Area { (*self).layout(area) }
    fn render (&self, output: &mut E) { (*self).render(output) }
}
/// The platonic ideal unit of [Content]: total emptiness at dead center.
impl<E: Output> Content<E> for () {
    fn layout (&self, area: E::Area) -> E::Area { area.center().to_area_pos().into() }
    fn render (&self, _: &mut E) {}
}
impl<E: Output, T: Content<E>> Content<E> for Option<T> {
    fn content (&self) -> impl Render<E> {
        self.as_ref()
    }
    fn layout (&self, area: E::Area) -> E::Area {
        self.as_ref()
            .map(|content|content.layout(area))
            .unwrap_or([0.into(), 0.into(), 0.into(), 0.into(),].into())
    }
    fn render (&self, output: &mut E) {
        self.as_ref()
            .map(|content|content.render(output));
    }
}
//impl<E: Output, T: Content<E>, E: Content<E>> Content<E> for Option<T> {
    //fn content (&self) -> impl Render<E> {
        //self.as_ref()
    //}
    //fn layout (&self, area: E::Area) -> E::Area {
        //self.as_ref()
            //.map(|content|content.layout(area))
            //.unwrap_or([0.into(), 0.into(), 0.into(), 0.into(),].into())
    //}
    //fn render (&self, output: &mut E) {
        //self.as_ref()
            //.map(|content|content.render(output));
    //}
//}