1use crate::{
  2    AnyElement, Element, IntoAnyElement, Layout, LayoutId, Line, Pixels, Result, Size, ViewContext,
  3};
  4use parking_lot::Mutex;
  5use std::{marker::PhantomData, sync::Arc};
  6use util::arc_cow::ArcCow;
  7
  8impl<S: 'static> IntoAnyElement<S> for ArcCow<'static, str> {
  9    fn into_any(self) -> AnyElement<S> {
 10        Text {
 11            text: self,
 12            state_type: PhantomData,
 13        }
 14        .into_any()
 15    }
 16}
 17
 18impl<V: 'static> IntoAnyElement<V> for &'static str {
 19    fn into_any(self) -> AnyElement<V> {
 20        Text {
 21            text: ArcCow::from(self),
 22            state_type: PhantomData,
 23        }
 24        .into_any()
 25    }
 26}
 27
 28pub struct Text<S> {
 29    text: ArcCow<'static, str>,
 30    state_type: PhantomData<S>,
 31}
 32
 33impl<S: 'static> Element for Text<S> {
 34    type State = S;
 35    type FrameState = Arc<Mutex<Option<TextLayout>>>;
 36
 37    fn layout(
 38        &mut self,
 39        _view: &mut S,
 40        cx: &mut ViewContext<S>,
 41    ) -> Result<(LayoutId, Self::FrameState)> {
 42        let text_system = cx.text_system().clone();
 43        let text_style = cx.text_style();
 44        let font_size = text_style.font_size * cx.rem_size();
 45        let line_height = text_style
 46            .line_height
 47            .to_pixels(font_size.into(), cx.rem_size());
 48        let text = self.text.clone();
 49        let paint_state = Arc::new(Mutex::new(None));
 50
 51        let rem_size = cx.rem_size();
 52        let layout_id = cx.request_measured_layout(Default::default(), rem_size, {
 53            let frame_state = paint_state.clone();
 54            move |_, _| {
 55                let line_layout = text_system.layout_str(
 56                    text.as_ref(),
 57                    font_size,
 58                    &[(text.len(), text_style.to_run())],
 59                );
 60
 61                let size = Size {
 62                    width: line_layout.width(),
 63                    height: line_height,
 64                };
 65
 66                frame_state.lock().replace(TextLayout {
 67                    line: Arc::new(line_layout),
 68                    line_height,
 69                });
 70
 71                size
 72            }
 73        });
 74
 75        Ok((layout_id?, paint_state))
 76    }
 77
 78    fn paint<'a>(
 79        &mut self,
 80        layout: Layout,
 81        _: &mut Self::State,
 82        paint_state: &mut Self::FrameState,
 83        cx: &mut ViewContext<S>,
 84    ) -> Result<()> {
 85        let bounds = layout.bounds;
 86
 87        let line;
 88        let line_height;
 89        {
 90            let paint_state = paint_state.lock();
 91            let paint_state = paint_state
 92                .as_ref()
 93                .expect("measurement has not been performed");
 94            line = paint_state.line.clone();
 95            line_height = paint_state.line_height;
 96        }
 97
 98        let _text_style = cx.text_style();
 99
100        // todo!("We haven't added visible bounds to the new element system yet, so this is a placeholder.");
101        let visible_bounds = bounds;
102        line.paint(bounds.origin, visible_bounds, line_height, cx)?;
103
104        Ok(())
105    }
106}
107
108pub struct TextLayout {
109    line: Arc<Line>,
110    line_height: Pixels,
111}