529 lines
14 KiB
Rust
529 lines
14 KiB
Rust
use crate::{
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AvailableSpace, BorrowWindow, Bounds, ElementId, LayoutId, Pixels, Point, Size, ViewContext,
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WindowContext,
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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 Render: 'static + Sized {
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type Element: Element + 'static;
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fn render(&mut self, cx: &mut ViewContext<Self>) -> Self::Element;
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}
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pub trait IntoElement: Sized {
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type Element: Element + 'static;
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fn element_id(&self) -> Option<ElementId>;
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fn into_element(self) -> Self::Element;
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fn into_any_element(self) -> AnyElement {
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self.into_element().into_any()
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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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cx: &mut WindowContext,
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f: impl FnOnce(&mut <Self::Element as Element>::State, &mut WindowContext) -> 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 = self.into_element();
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let element_id = element.element_id();
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let element = DrawableElement {
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element: Some(element),
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phase: ElementDrawPhase::Start,
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};
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let frame_state =
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DrawableElement::draw(element, origin, available_space.map(Into::into), 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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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: IntoElement,
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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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pub trait Element: 'static + IntoElement {
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type State: 'static;
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fn layout(
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&mut self,
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state: Option<Self::State>,
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cx: &mut WindowContext,
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) -> (LayoutId, Self::State);
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fn paint(self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext);
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fn into_any(self) -> AnyElement {
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AnyElement::new(self)
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}
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}
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pub trait RenderOnce: 'static {
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type Rendered: IntoElement;
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fn render(self, cx: &mut WindowContext) -> Self::Rendered;
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}
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pub struct Component<C> {
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component: Option<C>,
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}
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pub struct CompositeElementState<C: RenderOnce> {
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rendered_element: Option<<C::Rendered as IntoElement>::Element>,
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rendered_element_state: Option<<<C::Rendered as IntoElement>::Element as Element>::State>,
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}
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impl<C> Component<C> {
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pub fn new(component: C) -> Self {
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Component {
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component: Some(component),
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}
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}
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}
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impl<C: RenderOnce> Element for Component<C> {
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type State = CompositeElementState<C>;
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fn layout(
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&mut self,
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state: Option<Self::State>,
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cx: &mut WindowContext,
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) -> (LayoutId, Self::State) {
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let mut element = self.component.take().unwrap().render(cx).into_element();
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if let Some(element_id) = element.element_id() {
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let layout_id =
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cx.with_element_state(element_id, |state, cx| element.layout(state, cx));
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let state = CompositeElementState {
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rendered_element: Some(element),
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rendered_element_state: None,
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};
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(layout_id, state)
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} else {
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let (layout_id, state) =
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element.layout(state.and_then(|s| s.rendered_element_state), cx);
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let state = CompositeElementState {
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rendered_element: Some(element),
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rendered_element_state: Some(state),
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};
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(layout_id, state)
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}
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}
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fn paint(self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext) {
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let element = state.rendered_element.take().unwrap();
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if let Some(element_id) = element.element_id() {
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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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element.paint(bounds, &mut element_state, cx);
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((), element_state)
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});
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} else {
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element.paint(
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bounds,
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&mut state.rendered_element_state.as_mut().unwrap(),
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cx,
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);
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}
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}
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}
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impl<C: RenderOnce> IntoElement for Component<C> {
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type Element = Self;
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fn element_id(&self) -> Option<ElementId> {
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None
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}
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fn into_element(self) -> Self::Element {
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self
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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 ParentElement {
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fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]>;
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fn child(mut self, child: impl IntoElement) -> 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_element().into_any());
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self
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}
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fn children(mut self, children: impl IntoIterator<Item = impl IntoElement>) -> 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(|child| child.into_any_element()));
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self
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}
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}
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trait ElementObject {
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fn element_id(&self) -> Option<ElementId>;
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fn layout(&mut self, cx: &mut WindowContext) -> LayoutId;
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fn paint(&mut self, cx: &mut WindowContext);
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fn measure(
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&mut self,
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available_space: Size<AvailableSpace>,
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cx: &mut WindowContext,
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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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cx: &mut WindowContext,
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);
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}
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pub struct DrawableElement<E: Element> {
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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<S> {
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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<S>,
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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<S>,
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},
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}
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/// A wrapper around an implementer of [Element] that allows it to be drawn in a window.
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impl<E: Element> DrawableElement<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, cx: &mut WindowContext) -> 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.as_mut().unwrap().layout(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(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, cx: &mut WindowContext) -> 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, &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
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.take()
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.unwrap()
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.paint(bounds, &mut element_state, cx);
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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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cx: &mut WindowContext,
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) -> Size<Pixels> {
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if matches!(&self.phase, ElementDrawPhase::Start) {
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self.layout(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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cx: &mut WindowContext,
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) -> Option<E::State> {
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self.measure(available_space, cx);
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cx.with_absolute_element_offset(origin, |cx| self.paint(cx))
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}
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}
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impl<E> ElementObject for Option<DrawableElement<E>>
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where
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E: Element,
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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, cx: &mut WindowContext) -> LayoutId {
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DrawableElement::layout(self.as_mut().unwrap(), cx)
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}
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fn paint(&mut self, cx: &mut WindowContext) {
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DrawableElement::paint(self.take().unwrap(), 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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cx: &mut WindowContext,
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) -> Size<Pixels> {
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DrawableElement::measure(self.as_mut().unwrap(), available_space, 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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cx: &mut WindowContext,
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) {
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DrawableElement::draw(self.take().unwrap(), origin, available_space, cx);
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}
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}
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pub struct AnyElement(Box<dyn ElementObject>);
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impl AnyElement {
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pub fn new<E>(element: E) -> Self
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where
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E: 'static + Element,
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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>)
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}
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pub fn layout(&mut self, cx: &mut WindowContext) -> LayoutId {
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self.0.layout(cx)
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}
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pub fn paint(mut self, cx: &mut WindowContext) {
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self.0.paint(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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cx: &mut WindowContext,
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) -> Size<Pixels> {
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self.0.measure(available_space, 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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cx: &mut WindowContext,
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) {
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self.0.draw(origin, available_space, cx)
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}
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/// Converts this `AnyElement` into a trait object that can be stored and manipulated.
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pub fn into_any(self) -> AnyElement {
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AnyElement::new(self)
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}
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pub fn inner_id(&self) -> Option<ElementId> {
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self.0.element_id()
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}
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}
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impl Element for AnyElement {
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type State = ();
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fn layout(
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&mut self,
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_: Option<Self::State>,
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cx: &mut WindowContext,
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) -> (LayoutId, Self::State) {
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let layout_id = self.layout(cx);
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(layout_id, ())
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}
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fn paint(self, _: Bounds<Pixels>, _: &mut Self::State, cx: &mut WindowContext) {
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self.paint(cx);
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}
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}
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impl IntoElement for AnyElement {
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type Element = Self;
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fn element_id(&self) -> Option<ElementId> {
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None
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}
|
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fn into_element(self) -> Self::Element {
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self
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}
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}
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// impl<V, E, F> Element for Option<F>
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// where
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// V: 'static,
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// E: Element,
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// F: FnOnce(&mut V, &mut WindowContext<'_, V>) -> E + 'static,
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// {
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// type State = Option<AnyElement>;
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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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// _: Option<Self::State>,
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// cx: &mut WindowContext,
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// ) -> (LayoutId, Self::State) {
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// let render = self.take().unwrap();
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// let mut element = (render)(view_state, cx).into_any();
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// let layout_id = element.layout(view_state, cx);
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// (layout_id, Some(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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// rendered_element: &mut Self::State,
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// cx: &mut WindowContext,
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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> RenderOnce for Option<F>
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// where
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// V: 'static,
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// E: Element,
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// F: FnOnce(&mut V, &mut WindowContext) -> E + 'static,
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// {
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// type Element = Self;
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// fn render(self) -> Self::Element {
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// self
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// }
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// }
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