Fix text wrapping when a child of a v_stack() (#3362)

Previously text that was rendered in a flex-column would reserve the
correct
amount of space during layout, and then paint itself incorrectly.

Release Notes:

- N/A

crates/gpui2/src/elements/text.rs

@@ -64,19 +64,34 @@ impl<V: 'static> Element<V> for Text {
 
         let layout_id = cx.request_measured_layout(Default::default(), rem_size, {
             let element_state = element_state.clone();
-            move |known_dimensions, _| {
+            move |known_dimensions, available_space| {
+                let wrap_width = known_dimensions.width.or(match available_space.width {
+                    crate::AvailableSpace::Definite(x) => Some(x),
+                    _ => None,
+                });
+
+                if let Some(text_state) = element_state.0.lock().as_ref() {
+                    if text_state.size.is_some()
+                        && (wrap_width.is_none() || wrap_width == text_state.wrap_width)
+                    {
+                        return text_state.size.unwrap();
+                    }
+                }
+
                 let Some(lines) = text_system
                     .shape_text(
                         &text,
                         font_size,
                         &runs[..],
-                        known_dimensions.width, // Wrap if we know the width.
+                        wrap_width, // Wrap if we know the width.
                     )
                     .log_err()
                 else {
                     element_state.lock().replace(TextStateInner {
                         lines: Default::default(),
                         line_height,
+                        wrap_width,
+                        size: Some(Size::default()),
                     });
                     return Size::default();
                 };
@@ -88,9 +103,12 @@ impl<V: 'static> Element<V> for Text {
                     size.width = size.width.max(line_size.width);
                 }
 
-                element_state
-                    .lock()
-                    .replace(TextStateInner { lines, line_height });
+                element_state.lock().replace(TextStateInner {
+                    lines,
+                    line_height,
+                    wrap_width,
+                    size: Some(size),
+                });
 
                 size
             }
@@ -133,6 +151,8 @@ impl TextState {
 struct TextStateInner {
     lines: SmallVec<[WrappedLine; 1]>,
     line_height: Pixels,
+    wrap_width: Option<Pixels>,
+    size: Option<Size<Pixels>>,
 }
 
 struct InteractiveText {

crates/gpui2/src/taffy.rs

@@ -5,12 +5,14 @@ use std::fmt::Debug;
 use taffy::{
     geometry::{Point as TaffyPoint, Rect as TaffyRect, Size as TaffySize},
     style::AvailableSpace as TaffyAvailableSpace,
-    tree::{Measurable, MeasureFunc, NodeId},
+    tree::NodeId,
     Taffy,
 };
 
+type Measureable = dyn Fn(Size<Option<Pixels>>, Size<AvailableSpace>) -> Size<Pixels> + Send + Sync;
+
 pub struct TaffyLayoutEngine {
-    taffy: Taffy,
+    taffy: Taffy<Box<Measureable>>,
     children_to_parents: HashMap<LayoutId, LayoutId>,
     absolute_layout_bounds: HashMap<LayoutId, Bounds<Pixels>>,
     computed_layouts: HashSet<LayoutId>,
@@ -70,9 +72,9 @@ impl TaffyLayoutEngine {
     ) -> LayoutId {
         let style = style.to_taffy(rem_size);
 
-        let measurable = Box::new(Measureable(measure)) as Box<dyn Measurable>;
+        let measurable = Box::new(measure);
         self.taffy
-            .new_leaf_with_measure(style, MeasureFunc::Boxed(measurable))
+            .new_leaf_with_context(style, measurable)
             .expect(EXPECT_MESSAGE)
             .into()
     }
@@ -154,7 +156,22 @@ impl TaffyLayoutEngine {
 
         // let started_at = std::time::Instant::now();
         self.taffy
-            .compute_layout(id.into(), available_space.into())
+            .compute_layout_with_measure(
+                id.into(),
+                available_space.into(),
+                |known_dimensions, available_space, _node_id, context| {
+                    let Some(measure) = context else {
+                        return taffy::geometry::Size::default();
+                    };
+
+                    let known_dimensions = Size {
+                        width: known_dimensions.width.map(Pixels),
+                        height: known_dimensions.height.map(Pixels),
+                    };
+
+                    measure(known_dimensions, available_space.into()).into()
+                },
+            )
             .expect(EXPECT_MESSAGE);
         // println!("compute_layout took {:?}", started_at.elapsed());
     }
@@ -202,25 +219,6 @@ impl From<LayoutId> for NodeId {
     }
 }
 
-struct Measureable<F>(F);
-
-impl<F> taffy::tree::Measurable for Measureable<F>
-where
-    F: Fn(Size<Option<Pixels>>, Size<AvailableSpace>) -> Size<Pixels> + Send + Sync,
-{
-    fn measure(
-        &self,
-        known_dimensions: TaffySize<Option<f32>>,
-        available_space: TaffySize<TaffyAvailableSpace>,
-    ) -> TaffySize<f32> {
-        let known_dimensions: Size<Option<f32>> = known_dimensions.into();
-        let known_dimensions: Size<Option<Pixels>> = known_dimensions.map(|d| d.map(Into::into));
-        let available_space = available_space.into();
-        let size = (self.0)(known_dimensions, available_space);
-        size.into()
-    }
-}
-
 trait ToTaffy<Output> {
     fn to_taffy(&self, rem_size: Pixels) -> Output;
 }