fix(core): 🐛 changing flex does not relayout

CHANGELOG.md

@@ -36,6 +36,7 @@ Please only add new entries below the [Unreleased](#unreleased---releasedate) he
 
 - **core**: The `Provider` might be missing in a pipe class. (#648 @M-Adoo)
 - **core**: The child generated by the class may not be mounted. (#648 @M-Adoo)
+- **widgets**: Changing the `flex` of `Expanded` does not trigger a relayout. (#652 @M-Adoo)
 
 ### Breaking
 

core/src/builtin_widgets/keep_alive.rs

@@ -29,7 +29,7 @@ impl<'c> ComposeChild<'c> for KeepAlive {
     let modifies = this.raw_modifies();
     child
       .try_unwrap_state_and_attach(this)
-      .on_build(|id| id.dirty_subscribe(modifies, BuildCtx::get_mut().tree_mut()))
+      .on_build(|id| id.dirty_on(modifies))
   }
 }
 

core/src/builtin_widgets/smooth_layout.rs

@@ -101,7 +101,7 @@ macro_rules! smooth_size_widget_impl {
         fn_widget!{
           let modifies = this.read().0.raw_modifies();
           WrapRender::combine_child(this, child)
-            .on_build(move |id, | id.dirty_subscribe(modifies, BuildCtx::get_mut().tree_mut()) )
+            .on_build(move |id, | id.dirty_on(modifies) )
         }.into_widget()
       }
     }

core/src/state.rs

@@ -399,7 +399,7 @@ where
         Err(s) => {
           let modifies = s.raw_modifies();
           let w = ReaderRender(s.clone_reader()).into_widget();
-          w.on_build(move |id| id.dirty_subscribe(modifies, BuildCtx::get_mut().tree_mut()))
+          w.on_build(move |id| id.dirty_on(modifies))
         }
       },
     }

core/src/widget.rs

@@ -191,7 +191,7 @@ impl<'w> Widget<'w> {
     self.on_build(|id| id.attach_anonymous_data(data, BuildCtx::get_mut().tree_mut()))
   }
 
-  pub(crate) fn attach_data(self, data: Box<dyn Query>) -> Self {
+  pub fn attach_data(self, data: Box<dyn Query>) -> Self {
     self.on_build(|id| id.attach_data(data, BuildCtx::get_mut().tree_mut()))
   }
 

core/src/widget_tree/widget_id.rs

@@ -35,11 +35,14 @@ impl WidgetId {
     tree.arena.get(self.0).map(|n| &**n.get())
   }
 
-  /// Subscribe the modifies `upstream` to mark the widget dirty when the
-  /// `upstream` emit a modify event that contains `ModifyScope::FRAMEWORK`.
-  pub(crate) fn dirty_subscribe(
-    self, upstream: CloneableBoxOp<'static, ModifyScope, Infallible>, tree: &mut WidgetTree,
-  ) {
+  /// Subscribe to the modified `upstream` to mark the widget as dirty when the
+  /// `upstream` emits a modify event containing `ModifyScope::FRAMEWORK`.
+  ///
+  /// # Panic
+  /// This method only works within a build process; otherwise, it will
+  /// result in a panic.
+  pub fn dirty_on(self, upstream: CloneableBoxOp<'static, ModifyScope, Infallible>) {
+    let tree = BuildCtx::get_mut().tree_mut();
     let dirty_set = tree.dirty_set.clone();
     let h = upstream
       .filter(|b| b.contains(ModifyScope::FRAMEWORK))

core/src/wrap_render.rs

@@ -36,24 +36,20 @@ pub trait WrapRender {
     Self: Sized + 'static,
   {
     child.on_build(move |id| {
-      let mut modifies = None;
       let tree = BuildCtx::get_mut().tree_mut();
       id.wrap_node(tree, |r| match this.try_into_value() {
         Ok(this) => Box::new(RenderPair { wrapper: Box::new(this), host: r }),
         Err(this) => {
           let reader = match this.into_reader() {
             Ok(r) => r,
             Err(s) => {
-              modifies = Some(s.raw_modifies());
+              id.dirty_on(s.raw_modifies());
               s.clone_reader()
             }
           };
           Box::new(RenderPair { wrapper: Box::new(reader), host: r })
         }
       });
-      if let Some(modifies) = modifies {
-        id.dirty_subscribe(modifies, tree);
-      }
     })
   }
 }

widgets/src/layout/expanded.rs

@@ -16,14 +16,23 @@ pub struct Expanded {
 impl<'c> ComposeChild<'c> for Expanded {
   type Child = Widget<'c>;
   #[inline]
-  fn compose_child(this: impl StateWriter<Value = Self>, child: Self::Child) -> Widget<'c> {
-    child.try_unwrap_state_and_attach(this)
+  fn compose_child(this: impl StateWriter<Value = Self>, mut child: Self::Child) -> Widget<'c> {
+    let data: Box<dyn Query> = match this.try_into_value() {
+      Ok(this) => Box::new(Queryable(this)),
+      Err(this) => {
+        let modifies = this.raw_modifies();
+        child = child.on_build(|id| id.dirty_on(modifies));
+        Box::new(this)
+      }
+    };
+
+    child.attach_data(data)
   }
 }
 
 #[cfg(test)]
 mod tests {
-  use ribir_core::test_helper::*;
+  use ribir_core::{reset_test_env, test_helper::*};
   use ribir_dev_helper::*;
 
   use super::*;
@@ -88,4 +97,31 @@ mod tests {
     LayoutCase::new(&[0, 5]).with_rect(ribir_geom::rect(100., 50., 50., 50.)),
     LayoutCase::new(&[0, 6]).with_rect(ribir_geom::rect(150., 50., 200., 50.))
   );
+
+  #[test]
+  fn modifies_flex() {
+    reset_test_env!();
+
+    let (flex, w_flex) = split_value(1f32);
+    let widget = fn_widget! {
+      let expanded = @Expanded { flex: 1. };
+      watch!(*$flex).subscribe(move |val| $expanded.write().flex = val);
+
+      @Row {
+        @ $expanded { @ { Void } }
+        @Expanded {
+          flex: 1.,
+          @ { Void }
+        }
+        @SizedBox { size: Size::new(100., 100.) }
+      }
+    };
+
+    let mut wnd = TestWindow::new_with_size(widget, Size::new(400., 100.));
+    wnd.draw_frame();
+    LayoutCase::expect_size(&wnd, &[0, 0], Size::new(150., 0.));
+    *w_flex.write() = 2.;
+    wnd.draw_frame();
+    LayoutCase::expect_size(&wnd, &[0, 0], Size::new(200., 0.));
+  }
 }