1use crate::{
  2    AnyElement, Element, IntoAnyElement, Layout, LayoutId, Line, LineLayout, Pixels, Result, Size,
  3    ViewContext,
  4};
  5use parking_lot::Mutex;
  6use std::{marker::PhantomData, sync::Arc};
  7use util::arc_cow::ArcCow;
  8
  9impl<S: 'static> IntoAnyElement<S> for ArcCow<'static, str> {
 10    fn into_any(self) -> AnyElement<S> {
 11        Text {
 12            text: self,
 13            state_type: PhantomData,
 14        }
 15        .into_any()
 16    }
 17}
 18
 19impl<V: 'static> IntoAnyElement<V> for &'static str {
 20    fn into_any(self) -> AnyElement<V> {
 21        Text {
 22            text: ArcCow::from(self),
 23            state_type: PhantomData,
 24        }
 25        .into_any()
 26    }
 27}
 28
 29pub struct Text<S> {
 30    text: ArcCow<'static, str>,
 31    state_type: PhantomData<S>,
 32}
 33
 34impl<S: 'static> Element for Text<S> {
 35    type State = S;
 36    type FrameState = Arc<Mutex<Option<TextLayout>>>;
 37
 38    fn layout(
 39        &mut self,
 40        _view: &mut S,
 41        cx: &mut ViewContext<S>,
 42    ) -> Result<(LayoutId, Self::FrameState)> {
 43        let text_system = cx.text_system().clone();
 44        let text_style = cx.text_style();
 45        let line_height = cx.text_system().line_height(text_style.font_size);
 46        let text = self.text.clone();
 47        let paint_state = Arc::new(Mutex::new(None));
 48
 49        let layout_id = cx.request_measured_layout(Default::default(), cx.rem_size(), {
 50            let frame_state = paint_state.clone();
 51            move |_, _| {
 52                let line_layout = text_system.layout_str(
 53                    text.as_ref(),
 54                    text_style.font_size,
 55                    &[(text.len(), text_style.to_run())],
 56                );
 57
 58                let size = Size {
 59                    width: line_layout.width(),
 60                    height: line_height,
 61                };
 62
 63                frame_state.lock().replace(TextLayout {
 64                    line: Arc::new(line_layout),
 65                    line_height,
 66                });
 67
 68                size
 69            }
 70        });
 71
 72        Ok((layout_id?, paint_state))
 73    }
 74
 75    fn paint<'a>(
 76        &mut self,
 77        layout: Layout,
 78        _: &mut Self::State,
 79        paint_state: &mut Self::FrameState,
 80        cx: &mut ViewContext<S>,
 81    ) {
 82        let bounds = layout.bounds;
 83
 84        let line;
 85        let line_height;
 86        {
 87            let paint_state = paint_state.lock();
 88            let paint_state = paint_state
 89                .as_ref()
 90                .expect("measurement has not been performed");
 91            line = paint_state.line.clone();
 92            line_height = paint_state.line_height;
 93        }
 94
 95        let text_style = cx.text_style();
 96
 97        // todo!("We haven't added visible bounds to the new element system yet, so this is a placeholder.");
 98        let visible_bounds = bounds;
 99        line.paint(bounds.origin, visible_bounds, line_height, cx.legacy_cx);
100    }
101}
102
103pub struct TextLayout {
104    line: Arc<Line>,
105    line_height: Pixels,
106}