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::MouseButtonEvent, LayoutId};
 10use refineable::{CascadeSlot, Refineable, RefinementCascade};
 11use smallvec::SmallVec;
 12use std::{cell::Cell, rc::Rc};
 13
 14pub struct Pressable<E: Styleable> {
 15    pressed: Rc<Cell<bool>>,
 16    pressed_style: <E::Style as Refineable>::Refinement,
 17    cascade_slot: CascadeSlot,
 18    child: E,
 19}
 20
 21pub fn pressable<E: Styleable>(mut child: E) -> Pressable<E> {
 22    Pressable {
 23        pressed: Rc::new(Cell::new(false)),
 24        pressed_style: Default::default(),
 25        cascade_slot: child.style_cascade().reserve(),
 26        child,
 27    }
 28}
 29
 30impl<E: Styleable> Styleable for Pressable<E> {
 31    type Style = E::Style;
 32
 33    fn declared_style(&mut self) -> &mut <Self::Style as Refineable>::Refinement {
 34        &mut self.pressed_style
 35    }
 36
 37    fn style_cascade(&mut self) -> &mut RefinementCascade<E::Style> {
 38        self.child.style_cascade()
 39    }
 40}
 41
 42impl<V: 'static, E: Element<V> + Styleable> Element<V> for Pressable<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        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        let slot = self.cascade_slot;
 66        let style = self.pressed.get().then_some(self.pressed_style.clone());
 67        self.style_cascade().set(slot, style);
 68
 69        let pressed = self.pressed.clone();
 70        let bounds = layout.bounds;
 71        cx.on_event(layout.order, move |_view, event: &MouseButtonEvent, cx| {
 72            if event.is_down {
 73                if bounds.contains_point(event.position) {
 74                    pressed.set(true);
 75                    cx.repaint();
 76                }
 77            } else if pressed.get() {
 78                pressed.set(false);
 79                cx.repaint();
 80            }
 81        });
 82
 83        self.child.paint(view, layout, paint_state, cx);
 84    }
 85}
 86
 87impl<E: Styleable<Style = Style>> StyleHelpers for Pressable<E> {}
 88
 89impl<V: 'static, E: Interactive<V> + Styleable> Interactive<V> for Pressable<E> {
 90    fn interaction_handlers(&mut self) -> &mut InteractionHandlers<V> {
 91        self.child.interaction_handlers()
 92    }
 93}
 94
 95impl<V: 'static, E: ParentElement<V> + Styleable> ParentElement<V> for Pressable<E> {
 96    fn children_mut(&mut self) -> &mut SmallVec<[AnyElement<V>; 2]> {
 97        self.child.children_mut()
 98    }
 99}
100
101impl<V: 'static, E: Element<V> + Styleable> IntoElement<V> for Pressable<E> {
102    type Element = Self;
103
104    fn into_element(self) -> Self::Element {
105        self
106    }
107}