1use crate::{
  2    element::{AnyElement, Element, IntoElement, Layout, ParentElement},
  3    interactive::{InteractionHandlers, Interactive},
  4    layout_context::LayoutContext,
  5    paint_context::PaintContext,
  6    style::{Style, StyleHelpers, Styleable},
  7};
  8use anyhow::Result;
  9use gpui::{platform::MouseMovedEvent, LayoutId};
 10use refineable::{CascadeSlot, Refineable, RefinementCascade};
 11use smallvec::SmallVec;
 12use std::{cell::Cell, rc::Rc};
 13
 14pub struct Hoverable<E: Styleable> {
 15    hovered: Rc<Cell<bool>>,
 16    cascade_slot: CascadeSlot,
 17    hovered_style: <E::Style as Refineable>::Refinement,
 18    child: E,
 19}
 20
 21pub fn hoverable<E: Styleable>(mut child: E) -> Hoverable<E> {
 22    Hoverable {
 23        hovered: Rc::new(Cell::new(false)),
 24        cascade_slot: child.style_cascade().reserve(),
 25        hovered_style: Default::default(),
 26        child,
 27    }
 28}
 29
 30impl<E: Styleable> Styleable for Hoverable<E> {
 31    type Style = E::Style;
 32
 33    fn style_cascade(&mut self) -> &mut RefinementCascade<Self::Style> {
 34        self.child.style_cascade()
 35    }
 36
 37    fn declared_style(&mut self) -> &mut <Self::Style as Refineable>::Refinement {
 38        &mut self.hovered_style
 39    }
 40}
 41
 42impl<V: 'static, E: Element<V> + Styleable> Element<V> for Hoverable<E> {
 43    type PaintState = E::PaintState;
 44
 45    fn layout(
 46        &mut self,
 47        view: &mut V,
 48        cx: &mut LayoutContext<V>,
 49    ) -> Result<(LayoutId, Self::PaintState)>
 50    where
 51        Self: Sized,
 52    {
 53        Ok(self.child.layout(view, cx)?)
 54    }
 55
 56    fn paint(
 57        &mut self,
 58        view: &mut V,
 59        layout: &Layout,
 60        paint_state: &mut Self::PaintState,
 61        cx: &mut PaintContext<V>,
 62    ) where
 63        Self: Sized,
 64    {
 65        self.hovered
 66            .set(layout.bounds.contains_point(cx.mouse_position()));
 67
 68        let slot = self.cascade_slot;
 69        let style = self.hovered.get().then_some(self.hovered_style.clone());
 70        self.style_cascade().set(slot, style);
 71
 72        let hovered = self.hovered.clone();
 73        let bounds = layout.bounds;
 74        cx.on_event(layout.order, move |_view, _: &MouseMovedEvent, cx| {
 75            cx.bubble_event();
 76            if bounds.contains_point(cx.mouse_position()) != hovered.get() {
 77                cx.repaint();
 78            }
 79        });
 80
 81        self.child.paint(view, layout, paint_state, cx);
 82    }
 83}
 84
 85impl<E: Styleable<Style = Style>> StyleHelpers for Hoverable<E> {}
 86
 87impl<V: 'static, E: Interactive<V> + Styleable> Interactive<V> for Hoverable<E> {
 88    fn interaction_handlers(&mut self) -> &mut InteractionHandlers<V> {
 89        self.child.interaction_handlers()
 90    }
 91}
 92
 93impl<V: 'static, E: ParentElement<V> + Styleable> ParentElement<V> for Hoverable<E> {
 94    fn children_mut(&mut self) -> &mut SmallVec<[AnyElement<V>; 2]> {
 95        self.child.children_mut()
 96    }
 97}
 98
 99impl<V: 'static, E: Element<V> + Styleable> IntoElement<V> for Hoverable<E> {
100    type Element = Self;
101
102    fn into_element(self) -> Self::Element {
103        self
104    }
105}