feat(core): 🎸 add built-in providers

CHANGELOG.md

@@ -29,6 +29,7 @@ Please only add new entries below the [Unreleased](#unreleased---releasedate) he
 
 - **core**: The `Render::dirty_phase` method has been added to allow widgets to mark only the paint phase as dirty when it is modified. (#689 @M-Adoo)
 - **core**: Supports `Provider` to dirty the tree if it's a state writer. (#689 @M-Adoo)
+- **core**: Added the built-in field `providers` to provide data to its descendants. (#pr @M-Adoo)
 - **macros**: Added the `part_reader!` macro to generate a partial reader from a reference of a reader. (#688 @M-Adoo)
 - **macros**: The `simple_declare` now supports the `stateless` meta attribute, `#[simple_declare(stateless)]`. (#688 @M-Adoo)
 

core/src/builtin_widgets.rs

@@ -138,8 +138,9 @@ pub struct FatObj<T> {
   painting_style: Option<State<PaintingStyleWidget>>,
   text_style: Option<State<TextStyleWidget>>,
   keep_alive: Option<State<KeepAlive>>,
-  tooltips: Option<State<Tooltips>>,
   keep_alive_unsubscribe_handle: Option<Box<dyn Any>>,
+  tooltips: Option<State<Tooltips>>,
+  providers: Option<SmallVec<[Provider; 1]>>,
 }
 
 /// Create a function widget that uses an empty `FatObj` as the host object.
@@ -187,6 +188,7 @@ impl<T> FatObj<T> {
       tooltips: self.tooltips,
       keep_alive: self.keep_alive,
       keep_alive_unsubscribe_handle: self.keep_alive_unsubscribe_handle,
+      providers: self.providers,
     }
   }
 
@@ -770,7 +772,7 @@ impl<T> FatObj<T> {
     self.declare_builtin_init(v, Self::get_fitted_box_widget, |m, v| m.box_fit = v)
   }
 
-  /// Initializes the painting style of this widget.
+  /// Provide a painting style to this widget.
   pub fn painting_style<const M: usize>(self, v: impl DeclareInto<PaintingStyle, M>) -> Self {
     self.declare_builtin_init(v, Self::get_painting_style_widget, |m, v| m.painting_style = v)
   }
@@ -923,6 +925,16 @@ impl<T> FatObj<T> {
     self
   }
 
+  /// Initializes the providers of the widget.
+  pub fn providers(mut self, providers: impl Into<SmallVec<[Provider; 1]>>) -> Self {
+    if let Some(vec) = self.providers.as_mut() {
+      vec.extend(providers.into());
+    } else {
+      self.providers = Some(providers.into());
+    }
+    self
+  }
+
   fn declare_builtin_init<V: 'static, B: 'static, const M: usize>(
     mut self, init: impl DeclareInto<V, M>, get_builtin: impl FnOnce(&mut Self) -> &State<B>,
     set_value: fn(&mut B, V),
@@ -964,7 +976,7 @@ where
 }
 
 impl<'a> FatObj<Widget<'a>> {
-  fn compose(self) -> Widget<'a> {
+  fn compose(mut self) -> Widget<'a> {
     macro_rules! compose_builtin_widgets {
       ($host: ident + [$($field: ident),*]) => {
         $(
@@ -975,6 +987,19 @@ impl<'a> FatObj<Widget<'a>> {
       };
     }
     let mut host = self.host;
+    if let Some(painting_style) = self.painting_style {
+      self
+        .providers
+        .get_or_insert_default()
+        .push(PaintingStyleWidget::into_provider(painting_style));
+    }
+    if let Some(text_style) = self.text_style {
+      self
+        .providers
+        .get_or_insert_default()
+        .push(TextStyleWidget::into_provider(text_style));
+    }
+
     compose_builtin_widgets!(
       host
         + [
@@ -983,11 +1008,18 @@ impl<'a> FatObj<Widget<'a>> {
           fitted_box,
           foreground,
           box_decoration,
-          painting_style,
-          text_style,
           scrollable,
           layout_box,
-          class,
+          class
+        ]
+    );
+    if let Some(providers) = self.providers {
+      host = Providers::new(providers).with_child(host);
+    }
+
+    compose_builtin_widgets!(
+      host
+        + [
           constrained_box,
           tooltips,
           margin,

core/src/builtin_widgets/painting_style.rs

@@ -17,17 +17,18 @@ impl<'c> ComposeChild<'c> for PaintingStyleWidget {
   type Child = Widget<'c>;
 
   fn compose_child(this: impl StateWriter<Value = Self>, child: Self::Child) -> Widget<'c> {
-    // We need to provide the text style for the children to access.
-    let provider = match this.try_into_value() {
+    Providers::new([Self::into_provider(this)]).with_child(child)
+  }
+}
+
+impl PaintingStyleWidget {
+  pub fn into_provider(this: impl StateWriter<Value = Self>) -> Provider {
+    match this.try_into_value() {
       Ok(this) => Provider::new(this.painting_style),
       Err(this) => Provider::value_of_writer(
         this.map_writer(|w| PartData::from_ref_mut(&mut w.painting_style)),
         Some(DirtyPhase::LayoutSubtree),
       ),
-    };
-
-    Providers::new([provider])
-      .with_child(child)
-      .into_widget()
+    }
   }
 }

core/src/builtin_widgets/providers.rs

@@ -141,7 +141,7 @@ pub struct Providers {
   providers: RefCell<SmallVec<[Provider; 1]>>,
 }
 
-/// Macro used to generate a function widget using `BuildVariants` as the root
+/// Macro used to generate a function widget using `Providers` as the root
 /// widget.
 #[macro_export]
 macro_rules! providers {
@@ -297,9 +297,12 @@ impl Declare for Providers {
 }
 
 impl ProvidersDeclarer {
-  pub fn providers(mut self, variants: impl Into<SmallVec<[Provider; 1]>>) -> Self {
-    assert!(self.providers.is_none(), "Providers already initialized");
-    self.providers = Some(variants.into());
+  pub fn providers(mut self, providers: impl Into<SmallVec<[Provider; 1]>>) -> Self {
+    if let Some(vec) = self.providers.as_mut() {
+      vec.extend(providers.into());
+    } else {
+      self.providers = Some(providers.into());
+    }
     self
   }
 }

core/src/builtin_widgets/text_style.rs

@@ -16,17 +16,18 @@ impl<'c> ComposeChild<'c> for TextStyleWidget {
   type Child = Widget<'c>;
 
   fn compose_child(this: impl StateWriter<Value = Self>, child: Self::Child) -> Widget<'c> {
-    // We need to provide the text style for the children to access.
-    let provider = match this.try_into_value() {
+    Providers::new([Self::into_provider(this)]).with_child(child)
+  }
+}
+
+impl TextStyleWidget {
+  pub fn into_provider(this: impl StateWriter<Value = Self>) -> Provider {
+    match this.try_into_value() {
       Ok(this) => Provider::new(this.text_style),
       Err(this) => Provider::value_of_writer(
         this.map_writer(|w| PartData::from_ref_mut(&mut w.text_style)),
         Some(DirtyPhase::LayoutSubtree),
       ),
-    };
-
-    Providers::new([provider])
-      .with_child(child)
-      .into_widget()
+    }
   }
 }