1use parking_lot::Mutex;
  2
  3use crate::{
  4    AnyElement, Element, Handle, IntoAnyElement, Layout, LayoutId, Result, ViewContext,
  5    WindowContext,
  6};
  7use std::{any::Any, marker::PhantomData, sync::Arc};
  8
  9pub struct View<S: Send + Sync, P> {
 10    state: Handle<S>,
 11    render: Arc<dyn Fn(&mut S, &mut ViewContext<S>) -> AnyElement<S> + Send + Sync + 'static>,
 12    parent_state_type: PhantomData<P>,
 13}
 14
 15impl<S: 'static + Send + Sync, P: 'static + Send> View<S, P> {
 16    pub fn into_any(self) -> AnyView<P> {
 17        AnyView {
 18            view: Arc::new(Mutex::new(self)),
 19            parent_state_type: PhantomData,
 20        }
 21    }
 22}
 23
 24impl<S: Send + Sync, P> Clone for View<S, P> {
 25    fn clone(&self) -> Self {
 26        Self {
 27            state: self.state.clone(),
 28            render: self.render.clone(),
 29            parent_state_type: PhantomData,
 30        }
 31    }
 32}
 33
 34pub type RootView<S> = View<S, ()>;
 35
 36pub fn view<S, P, E>(
 37    state: Handle<S>,
 38    render: impl Fn(&mut S, &mut ViewContext<S>) -> E + Send + Sync + 'static,
 39) -> View<S, P>
 40where
 41    S: 'static + Send + Sync,
 42    P: 'static,
 43    E: Element<State = S>,
 44{
 45    View {
 46        state,
 47        render: Arc::new(move |state, cx| render(state, cx).into_any()),
 48        parent_state_type: PhantomData,
 49    }
 50}
 51
 52impl<S: Send + Sync + 'static, P: Send + 'static> Element for View<S, P> {
 53    type State = P;
 54    type FrameState = AnyElement<S>;
 55
 56    fn layout(
 57        &mut self,
 58        _: &mut Self::State,
 59        cx: &mut ViewContext<Self::State>,
 60    ) -> Result<(LayoutId, Self::FrameState)> {
 61        self.state.update(cx, |state, cx| {
 62            let mut element = (self.render)(state, cx);
 63            let layout_id = element.layout(state, cx)?;
 64            Ok((layout_id, element))
 65        })
 66    }
 67
 68    fn paint(
 69        &mut self,
 70        _: Layout,
 71        _: &mut Self::State,
 72        element: &mut Self::FrameState,
 73        cx: &mut ViewContext<Self::State>,
 74    ) -> Result<()> {
 75        self.state
 76            .update(cx, |state, cx| element.paint(state, None, cx))
 77    }
 78}
 79
 80trait ViewObject: Send + 'static {
 81    fn layout(&mut self, cx: &mut WindowContext) -> Result<(LayoutId, Box<dyn Any>)>;
 82    fn paint(
 83        &mut self,
 84        layout: Layout,
 85        element: &mut dyn Any,
 86        cx: &mut WindowContext,
 87    ) -> Result<()>;
 88}
 89
 90impl<S: Send + Sync + 'static, P: Send + 'static> ViewObject for View<S, P> {
 91    fn layout(&mut self, cx: &mut WindowContext) -> Result<(LayoutId, Box<dyn Any>)> {
 92        self.state.update(cx, |state, cx| {
 93            let mut element = (self.render)(state, cx);
 94            let layout_id = element.layout(state, cx)?;
 95            let element = Box::new(element) as Box<dyn Any>;
 96            Ok((layout_id, element))
 97        })
 98    }
 99
100    fn paint(&mut self, _: Layout, element: &mut dyn Any, cx: &mut WindowContext) -> Result<()> {
101        self.state.update(cx, |state, cx| {
102            element
103                .downcast_mut::<AnyElement<S>>()
104                .unwrap()
105                .paint(state, None, cx)
106        })
107    }
108}
109
110pub struct AnyView<S> {
111    view: Arc<Mutex<dyn ViewObject>>,
112    parent_state_type: PhantomData<S>,
113}
114
115impl<S: 'static> Element for AnyView<S> {
116    type State = ();
117    type FrameState = Box<dyn Any>;
118
119    fn layout(
120        &mut self,
121        _: &mut Self::State,
122        cx: &mut ViewContext<Self::State>,
123    ) -> Result<(LayoutId, Self::FrameState)> {
124        self.view.lock().layout(cx)
125    }
126
127    fn paint(
128        &mut self,
129        layout: Layout,
130        _: &mut Self::State,
131        element: &mut Self::FrameState,
132        cx: &mut ViewContext<Self::State>,
133    ) -> Result<()> {
134        self.view.lock().paint(layout, element, cx)
135    }
136}
137
138impl<S> Clone for AnyView<S> {
139    fn clone(&self) -> Self {
140        Self {
141            view: self.view.clone(),
142            parent_state_type: PhantomData,
143        }
144    }
145}