1use crate::{
  2    geometry::{rect::RectF, vector::Vector2F},
  3    sum_tree::{self, SumTree},
  4    Element,
  5};
  6use parking_lot::Mutex;
  7use std::sync::Arc;
  8
  9use crate::ElementBox;
 10
 11pub struct List {
 12    state: ListState,
 13}
 14
 15pub struct ListState(Arc<Mutex<StateInner>>);
 16
 17struct StateInner {
 18    elements: Vec<ElementBox>,
 19    heights: SumTree<ElementHeight>,
 20}
 21
 22#[derive(Clone, Debug)]
 23enum ElementHeight {
 24    Pending,
 25    Ready(f32),
 26}
 27
 28#[derive(Clone, Debug, Default)]
 29struct ElementHeightSummary {
 30    pending_count: usize,
 31    height: f32,
 32}
 33
 34impl Element for List {
 35    type LayoutState = ();
 36
 37    type PaintState = ();
 38
 39    fn layout(
 40        &mut self,
 41        constraint: crate::SizeConstraint,
 42        cx: &mut crate::LayoutContext,
 43    ) -> (Vector2F, Self::LayoutState) {
 44        todo!()
 45    }
 46
 47    fn after_layout(
 48        &mut self,
 49        size: Vector2F,
 50        layout: &mut Self::LayoutState,
 51        cx: &mut crate::AfterLayoutContext,
 52    ) {
 53        todo!()
 54    }
 55
 56    fn paint(
 57        &mut self,
 58        bounds: RectF,
 59        layout: &mut Self::LayoutState,
 60        cx: &mut crate::PaintContext,
 61    ) -> Self::PaintState {
 62        todo!()
 63    }
 64
 65    fn dispatch_event(
 66        &mut self,
 67        event: &crate::Event,
 68        bounds: RectF,
 69        layout: &mut Self::LayoutState,
 70        paint: &mut Self::PaintState,
 71        cx: &mut crate::EventContext,
 72    ) -> bool {
 73        todo!()
 74    }
 75
 76    fn debug(
 77        &self,
 78        bounds: RectF,
 79        layout: &Self::LayoutState,
 80        paint: &Self::PaintState,
 81        cx: &crate::DebugContext,
 82    ) -> serde_json::Value {
 83        todo!()
 84    }
 85}
 86
 87impl ListState {
 88    pub fn new(elements: Vec<ElementBox>) -> Self {
 89        let mut heights = SumTree::new();
 90        heights.extend(elements.iter().map(|_| ElementHeight::Pending), &());
 91        Self(Arc::new(Mutex::new(StateInner { elements, heights })))
 92    }
 93}
 94
 95impl sum_tree::Item for ElementHeight {
 96    type Summary = ElementHeightSummary;
 97
 98    fn summary(&self) -> Self::Summary {
 99        todo!()
100    }
101}
102
103impl sum_tree::Summary for ElementHeightSummary {
104    type Context = ();
105
106    fn add_summary(&mut self, summary: &Self, cx: &Self::Context) {
107        self.pending_count += summary.pending_count;
108        self.height += summary.height;
109    }
110}