504 lines
14 KiB
Rust
504 lines
14 KiB
Rust
use crate::{
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AvailableSpace, BorrowWindow, Bounds, ElementId, LayoutId, Pixels, Point, Size, ViewContext,
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};
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use derive_more::{Deref, DerefMut};
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pub(crate) use smallvec::SmallVec;
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use std::{any::Any, fmt::Debug};
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pub trait Element<V: 'static>: 'static + Sized {
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type State: 'static;
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fn element_id(&self) -> Option<ElementId>;
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fn layout(
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&mut self,
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view_state: &mut V,
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element_state: Option<Self::State>,
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cx: &mut ViewContext<V>,
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) -> (LayoutId, Self::State);
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fn paint(
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self,
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bounds: Bounds<Pixels>,
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view_state: &mut V,
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element_state: &mut Self::State,
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cx: &mut ViewContext<V>,
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);
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fn into_any(self) -> AnyElement<V> {
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AnyElement::new(self)
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}
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fn draw<T, R>(
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self,
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origin: Point<Pixels>,
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available_space: Size<T>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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f: impl FnOnce(&mut Self::State, &mut ViewContext<V>) -> R,
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) -> R
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where
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T: Clone + Default + Debug + Into<AvailableSpace>,
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{
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let element_id = self.element_id();
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let element = DrawableElement {
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element: Some(self),
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phase: ElementDrawPhase::Start,
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};
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let frame_state = element.draw(origin, available_space.map(Into::into), view_state, cx);
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if let Some(mut frame_state) = frame_state {
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f(&mut frame_state, cx)
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} else {
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cx.with_element_state(element_id.unwrap(), |element_state, cx| {
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let mut element_state = element_state.unwrap();
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let result = f(&mut element_state, cx);
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(result, element_state)
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})
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}
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}
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}
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#[derive(Deref, DerefMut, Default, Clone, Debug, Eq, PartialEq, Hash)]
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pub struct GlobalElementId(SmallVec<[ElementId; 32]>);
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pub trait ParentComponent<V: 'static> {
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fn children_mut(&mut self) -> &mut SmallVec<[AnyElement<V>; 2]>;
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fn child(mut self, child: impl Element<V>) -> Self
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where
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Self: Sized,
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{
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self.children_mut().push(child.into_any());
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self
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}
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fn children(mut self, children: impl IntoIterator<Item = impl Element<V>>) -> Self
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where
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Self: Sized,
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{
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self.children_mut()
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.extend(children.into_iter().map(Element::into_any));
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self
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}
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}
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trait ElementObject<V> {
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fn element_id(&self) -> Option<ElementId>;
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fn layout(&mut self, view_state: &mut V, cx: &mut ViewContext<V>) -> LayoutId;
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fn paint(&mut self, view_state: &mut V, cx: &mut ViewContext<V>);
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fn measure(
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&mut self,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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) -> Size<Pixels>;
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fn draw(
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&mut self,
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origin: Point<Pixels>,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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);
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}
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pub struct DrawableElement<V: 'static, E: Element<V>> {
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element: Option<E>,
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phase: ElementDrawPhase<E::State>,
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}
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#[derive(Default)]
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enum ElementDrawPhase<V> {
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#[default]
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Start,
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LayoutRequested {
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layout_id: LayoutId,
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frame_state: Option<V>,
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},
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LayoutComputed {
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layout_id: LayoutId,
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available_space: Size<AvailableSpace>,
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frame_state: Option<V>,
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},
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}
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/// Internal struct that wraps an element to store Layout and ElementState after the element is rendered.
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/// It's allocated as a trait object to erase the element type and wrapped in AnyElement<E::State> for
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/// improved usability.
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impl<V, E: Element<V>> DrawableElement<V, E> {
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fn new(element: E) -> Self {
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DrawableElement {
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element: Some(element),
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phase: ElementDrawPhase::Start,
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}
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}
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fn element_id(&self) -> Option<ElementId> {
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self.element.as_ref()?.element_id()
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}
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fn layout(&mut self, state: &mut V, cx: &mut ViewContext<V>) -> LayoutId {
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let (layout_id, frame_state) = if let Some(id) = self.element.as_ref().unwrap().element_id()
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{
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let layout_id = cx.with_element_state(id, |element_state, cx| {
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self.element
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.as_mut()
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.unwrap()
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.layout(state, element_state, cx)
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});
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(layout_id, None)
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} else {
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let (layout_id, frame_state) = self.element.as_mut().unwrap().layout(state, None, cx);
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(layout_id, Some(frame_state))
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};
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self.phase = ElementDrawPhase::LayoutRequested {
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layout_id,
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frame_state,
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};
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layout_id
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}
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fn paint(mut self, view_state: &mut V, cx: &mut ViewContext<V>) -> Option<E::State> {
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match self.phase {
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ElementDrawPhase::LayoutRequested {
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layout_id,
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frame_state,
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}
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| ElementDrawPhase::LayoutComputed {
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layout_id,
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frame_state,
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..
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} => {
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let bounds = cx.layout_bounds(layout_id);
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if let Some(mut frame_state) = frame_state {
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self.element
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.take()
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.unwrap()
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.paint(bounds, view_state, &mut frame_state, cx);
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Some(frame_state)
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} else {
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let element_id = self
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.element
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.as_ref()
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.unwrap()
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.element_id()
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.expect("if we don't have frame state, we should have element state");
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cx.with_element_state(element_id, |element_state, cx| {
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let mut element_state = element_state.unwrap();
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self.element.take().unwrap().paint(
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bounds,
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view_state,
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&mut element_state,
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cx,
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);
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((), element_state)
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});
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None
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}
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}
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_ => panic!("must call layout before paint"),
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}
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}
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fn measure(
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&mut self,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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) -> Size<Pixels> {
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if matches!(&self.phase, ElementDrawPhase::Start) {
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self.layout(view_state, cx);
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}
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let layout_id = match &mut self.phase {
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ElementDrawPhase::LayoutRequested {
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layout_id,
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frame_state,
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} => {
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cx.compute_layout(*layout_id, available_space);
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let layout_id = *layout_id;
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self.phase = ElementDrawPhase::LayoutComputed {
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layout_id,
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available_space,
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frame_state: frame_state.take(),
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};
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layout_id
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}
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ElementDrawPhase::LayoutComputed {
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layout_id,
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available_space: prev_available_space,
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..
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} => {
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if available_space != *prev_available_space {
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cx.compute_layout(*layout_id, available_space);
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*prev_available_space = available_space;
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}
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*layout_id
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}
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_ => panic!("cannot measure after painting"),
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};
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cx.layout_bounds(layout_id).size
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}
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fn draw(
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mut self,
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origin: Point<Pixels>,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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) -> Option<E::State> {
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self.measure(available_space, view_state, cx);
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cx.with_absolute_element_offset(origin, |cx| self.paint(view_state, cx))
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}
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}
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impl<V, E> ElementObject<V> for Option<DrawableElement<V, E>>
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where
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E: Element<V>,
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E::State: 'static,
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{
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fn element_id(&self) -> Option<ElementId> {
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self.as_ref().unwrap().element_id()
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}
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fn layout(&mut self, view_state: &mut V, cx: &mut ViewContext<V>) -> LayoutId {
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DrawableElement::layout(self.as_mut().unwrap(), view_state, cx)
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}
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fn paint(&mut self, view_state: &mut V, cx: &mut ViewContext<V>) {
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DrawableElement::paint(self.take().unwrap(), view_state, cx);
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}
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fn measure(
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&mut self,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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) -> Size<Pixels> {
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DrawableElement::measure(self.as_mut().unwrap(), available_space, view_state, cx)
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}
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fn draw(
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&mut self,
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origin: Point<Pixels>,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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) {
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DrawableElement::draw(
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self.take().unwrap(),
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origin,
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available_space,
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view_state,
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cx,
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);
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}
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}
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pub struct AnyElement<V>(Box<dyn ElementObject<V>>);
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impl<V> AnyElement<V> {
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pub fn new<E>(element: E) -> Self
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where
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V: 'static,
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E: 'static + Element<V>,
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E::State: Any,
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{
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AnyElement(Box::new(Some(DrawableElement::new(element))) as Box<dyn ElementObject<V>>)
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}
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pub fn element_id(&self) -> Option<ElementId> {
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self.0.element_id()
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}
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pub fn layout(&mut self, view_state: &mut V, cx: &mut ViewContext<V>) -> LayoutId {
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self.0.layout(view_state, cx)
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}
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pub fn paint(mut self, view_state: &mut V, cx: &mut ViewContext<V>) {
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self.0.paint(view_state, cx)
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}
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/// Initializes this element and performs layout within the given available space to determine its size.
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pub fn measure(
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&mut self,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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) -> Size<Pixels> {
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self.0.measure(available_space, view_state, cx)
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}
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/// Initializes this element and performs layout in the available space, then paints it at the given origin.
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pub fn draw(
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mut self,
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origin: Point<Pixels>,
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available_space: Size<AvailableSpace>,
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view_state: &mut V,
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cx: &mut ViewContext<V>,
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) {
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self.0.draw(origin, available_space, view_state, cx)
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}
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}
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impl<V: 'static> Element<V> for AnyElement<V> {
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type State = ();
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fn element_id(&self) -> Option<ElementId> {
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AnyElement::element_id(self)
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}
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fn layout(
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&mut self,
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view_state: &mut V,
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_: Option<Self::State>,
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cx: &mut ViewContext<V>,
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) -> (LayoutId, Self::State) {
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let layout_id = self.layout(view_state, cx);
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(layout_id, ())
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}
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fn paint(
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self,
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_bounds: Bounds<Pixels>,
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view_state: &mut V,
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_: &mut Self::State,
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cx: &mut ViewContext<V>,
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) {
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self.paint(view_state, cx);
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}
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}
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pub trait Component<V> {
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fn render(self) -> AnyElement<V>;
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fn map<U>(self, f: impl FnOnce(Self) -> U) -> U
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where
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Self: Sized,
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U: Component<V>,
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{
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f(self)
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}
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fn when(self, condition: bool, then: impl FnOnce(Self) -> Self) -> Self
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where
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Self: Sized,
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{
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self.map(|this| if condition { then(this) } else { this })
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}
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fn when_some<T>(self, option: Option<T>, then: impl FnOnce(Self, T) -> Self) -> Self
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where
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Self: Sized,
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{
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self.map(|this| {
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if let Some(value) = option {
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then(this, value)
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} else {
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this
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}
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})
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}
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}
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impl<V> Component<V> for AnyElement<V> {
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fn render(self) -> AnyElement<V> {
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self
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}
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}
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impl<V, E, F> Element<V> for Option<F>
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where
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V: 'static,
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E: 'static + Component<V>,
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F: FnOnce(&mut V, &mut ViewContext<'_, V>) -> E + 'static,
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{
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type State = Option<AnyElement<V>>;
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fn element_id(&self) -> Option<ElementId> {
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None
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}
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fn layout(
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&mut self,
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view_state: &mut V,
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_: Option<Self::State>,
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cx: &mut ViewContext<V>,
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) -> (LayoutId, Self::State) {
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let render = self.take().unwrap();
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let mut rendered_element = (render)(view_state, cx).render();
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let layout_id = rendered_element.layout(view_state, cx);
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(layout_id, Some(rendered_element))
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}
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fn paint(
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self,
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_bounds: Bounds<Pixels>,
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view_state: &mut V,
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rendered_element: &mut Self::State,
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cx: &mut ViewContext<V>,
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) {
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rendered_element.take().unwrap().paint(view_state, cx);
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}
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}
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impl<V, E, F> Component<V> for Option<F>
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where
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V: 'static,
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E: 'static + Component<V>,
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F: FnOnce(&mut V, &mut ViewContext<'_, V>) -> E + 'static,
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{
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fn render(self) -> AnyElement<V> {
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AnyElement::new(self)
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}
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}
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impl<V, E, F> Component<V> for F
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where
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V: 'static,
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E: 'static + Component<V>,
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F: FnOnce(&mut V, &mut ViewContext<'_, V>) -> E + 'static,
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{
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fn render(self) -> AnyElement<V> {
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AnyElement::new(Some(self))
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}
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}
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// impl<V, E, F> Element<V> for F
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// where
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// V: 'static,
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// E: 'static + Component<V>,
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// F: FnOnce(&mut V, &mut ViewContext<'_, V>) -> E + 'static,
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// {
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// type State = Option<AnyElement<V>>;
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// fn element_id(&self) -> Option<ElementId> {
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// None
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// }
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|
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// fn layout(
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// &mut self,
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// view_state: &mut V,
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// element_state: Option<Self::State>,
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// cx: &mut ViewContext<V>,
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// ) -> (LayoutId, Self::State) {
|
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|
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// self(view_state)
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// }
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// fn paint(
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// self,
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// bounds: Bounds<Pixels>,
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// view_state: &mut V,
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// element_state: &mut Self::State,
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// cx: &mut ViewContext<V>,
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// ) {
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// todo!()
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// }
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// }
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