RichText: Invalidate layout on Env change

druid/src/text/attribute.rs

@@ -19,6 +19,8 @@ use std::ops::Range;
 use crate::piet::{Color, FontFamily, FontStyle, FontWeight, TextAttribute as PietAttr};
 use crate::{Command, Env, FontDescriptor, KeyOrValue};
 
+use super::EnvUpdateCtx;
+
 /// A clickable range of text with an associated [`Command`].
 #[derive(Debug, Clone)]
 pub struct Link {
@@ -179,6 +181,16 @@ impl AttributeSpans {
         items.sort_by(|a, b| a.0.start.cmp(&b.0.start));
         items
     }
+
+    pub(crate) fn env_update(&self, ctx: &EnvUpdateCtx) -> bool {
+        self.size
+            .iter()
+            .any(|span_attr| ctx.env_key_changed(&span_attr.attr))
+            || self
+                .fg_color
+                .iter()
+                .any(|span_attr| ctx.env_key_changed(&span_attr.attr))
+    }
 }
 
 impl<T: Clone> SpanSet<T> {

druid/src/text/layout.rs

@@ -17,7 +17,7 @@
 use std::ops::Range;
 use std::rc::Rc;
 
-use super::{Link, TextStorage};
+use super::{EnvUpdateCtx, Link, TextStorage};
 use crate::kurbo::{Line, Point, Rect, Size};
 use crate::piet::{
     Color, PietText, PietTextLayout, Text as _, TextAlignment, TextAttribute, TextLayout as _,
@@ -347,6 +347,11 @@ impl<T: TextStorage> TextLayout<T> {
                     .text_size_override
                     .as_ref()
                     .map(|k| ctx.env_key_changed(k))
+                    .unwrap_or(false)
+                || self
+                    .text
+                    .as_ref()
+                    .map(|text| text.env_update(&EnvUpdateCtx::for_update(ctx)))
                     .unwrap_or(false);
 
             if rebuild {

druid/src/text/mod.rs

@@ -49,6 +49,6 @@ pub use self::movement::movement;
 pub use input_component::{EditSession, TextComponent};
 pub use input_methods::ImeHandlerRef;
 pub use rich_text::{AttributesAdder, RichText, RichTextBuilder};
-pub use storage::{ArcStr, TextStorage};
+pub use storage::{ArcStr, EnvUpdateCtx, TextStorage};
 
 pub(crate) use input_methods::TextFieldRegistration;

druid/src/text/rich_text.rs

@@ -18,7 +18,7 @@ use std::ops::{Range, RangeBounds};
 use std::sync::Arc;
 
 use super::attribute::Link;
-use super::{Attribute, AttributeSpans, TextStorage};
+use super::{Attribute, AttributeSpans, EnvUpdateCtx, TextStorage};
 use crate::piet::{
     util, Color, FontFamily, FontStyle, FontWeight, PietTextLayoutBuilder, TextLayoutBuilder,
     TextStorage as PietTextStorage,
@@ -93,6 +93,10 @@ impl TextStorage for RichText {
         builder
     }
 
+    fn env_update(&self, ctx: &EnvUpdateCtx) -> bool {
+        self.attrs.env_update(ctx)
+    }
+
     fn links(&self) -> &[Link] {
         &self.links
     }

druid/src/text/storage.rs

@@ -16,10 +16,12 @@
 
 use std::sync::Arc;
 
+use crate::env::KeyLike;
 use crate::piet::{PietTextLayoutBuilder, TextStorage as PietTextStorage};
 use crate::{Data, Env};
 
 use super::attribute::Link;
+use crate::UpdateCtx;
 
 /// A type that represents text that can be displayed.
 pub trait TextStorage: PietTextStorage + Data {
@@ -30,6 +32,13 @@ pub trait TextStorage: PietTextStorage + Data {
         builder
     }
 
+    /// This is called whenever the Env changes and should return true
+    /// if the layout should be rebuilt.
+    #[allow(unused_variables)]
+    fn env_update(&self, ctx: &EnvUpdateCtx) -> bool {
+        false
+    }
+
     /// Any additional [`Link`] attributes on this text.
     ///
     /// If this `TextStorage` object manages link attributes, it should implement this
@@ -45,6 +54,24 @@ pub trait TextStorage: PietTextStorage + Data {
     }
 }
 
+/// Provides information about keys change for more fine grained invalidation
+pub struct EnvUpdateCtx<'a, 'b>(&'a UpdateCtx<'a, 'b>);
+
+impl<'a, 'b> EnvUpdateCtx<'a, 'b> {
+    /// Create an EnvChangeCtx for Widget::update
+    pub(crate) fn for_update(ctx: &'a UpdateCtx<'a, 'b>) -> Self {
+        Self(ctx)
+    }
+
+    /// Returns `true` if the given key has changed since the last [`env_update`]
+    /// call.
+    ///
+    /// See [`UpdateCtx::env_key_changed`] for more details.
+    pub fn env_key_changed<T>(&self, key: &impl KeyLike<T>) -> bool {
+        self.0.env_key_changed(key)
+    }
+}
+
 /// A reference counted string slice.
 ///
 /// This is a data-friendly way to represent strings in druid. Unlike `String`