Introduce Widget::size_hint and fix further layout inconsistencies

widget/src/column.rs

@@ -22,16 +22,12 @@ pub struct Column<'a, Message, Renderer = crate::Renderer> {
     children: Vec<Element<'a, Message, Renderer>>,
 }
 
-impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
+impl<'a, Message, Renderer> Column<'a, Message, Renderer>
+where
+    Renderer: crate::core::Renderer,
+{
     /// Creates an empty [`Column`].
     pub fn new() -> Self {
-        Self::with_children(Vec::new())
-    }
-
-    /// Creates a [`Column`] with the given elements.
-    pub fn with_children(
-        children: Vec<Element<'a, Message, Renderer>>,
-    ) -> Self {
         Column {
             spacing: 0.0,
             padding: Padding::ZERO,
@@ -39,10 +35,17 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
             height: Length::Shrink,
             max_width: f32::INFINITY,
             align_items: Alignment::Start,
-            children,
+            children: Vec::new(),
         }
     }
 
+    /// Creates a [`Column`] with the given elements.
+    pub fn with_children(
+        children: impl Iterator<Item = Element<'a, Message, Renderer>>,
+    ) -> Self {
+        children.fold(Self::new(), |column, element| column.push(element))
+    }
+
     /// Sets the vertical spacing _between_ elements.
     ///
     /// Custom margins per element do not exist in iced. You should use this
@@ -88,12 +91,26 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
         mut self,
         child: impl Into<Element<'a, Message, Renderer>>,
     ) -> Self {
-        self.children.push(child.into());
+        let child = child.into();
+        let size = child.as_widget().size_hint();
+
+        if size.width.is_fill() {
+            self.width = Length::Fill;
+        }
+
+        if size.height.is_fill() {
+            self.height = Length::Fill;
+        }
+
+        self.children.push(child);
         self
     }
 }
 
-impl<'a, Message, Renderer> Default for Column<'a, Message, Renderer> {
+impl<'a, Message, Renderer> Default for Column<'a, Message, Renderer>
+where
+    Renderer: crate::core::Renderer,
+{
     fn default() -> Self {
         Self::new()
     }

widget/src/container.rs

@@ -46,11 +46,22 @@ where
     where
         T: Into<Element<'a, Message, Renderer>>,
     {
+        let content = content.into();
+        let size = content.as_widget().size_hint();
+
         Container {
             id: None,
             padding: Padding::ZERO,
-            width: Length::Shrink,
-            height: Length::Shrink,
+            width: if size.width.is_fill() {
+                Length::Fill
+            } else {
+                Length::Shrink
+            },
+            height: if size.height.is_fill() {
+                Length::Fill
+            } else {
+                Length::Shrink
+            },
             max_width: f32::INFINITY,
             max_height: f32::INFINITY,
             horizontal_alignment: alignment::Horizontal::Left,

widget/src/helpers.rs

@@ -34,7 +34,7 @@ macro_rules! column {
         $crate::Column::new()
     );
     ($($x:expr),+ $(,)?) => (
-        $crate::Column::with_children(vec![$($crate::core::Element::from($x)),+])
+        $crate::Column::with_children([$($crate::core::Element::from($x)),+].into_iter())
     );
 }
 
@@ -47,7 +47,7 @@ macro_rules! row {
         $crate::Row::new()
     );
     ($($x:expr),+ $(,)?) => (
-        $crate::Row::with_children(vec![$($crate::core::Element::from($x)),+])
+        $crate::Row::with_children([$($crate::core::Element::from($x)),+].into_iter())
     );
 }
 
@@ -65,9 +65,12 @@ where
 }
 
 /// Creates a new [`Column`] with the given children.
-pub fn column<Message, Renderer>(
-    children: Vec<Element<'_, Message, Renderer>>,
-) -> Column<'_, Message, Renderer> {
+pub fn column<'a, Message, Renderer>(
+    children: impl Iterator<Item = Element<'a, Message, Renderer>>,
+) -> Column<'a, Message, Renderer>
+where
+    Renderer: core::Renderer,
+{
     Column::with_children(children)
 }
 
@@ -84,9 +87,12 @@ where
 /// Creates a new [`Row`] with the given children.
 ///
 /// [`Row`]: crate::Row
-pub fn row<Message, Renderer>(
-    children: Vec<Element<'_, Message, Renderer>>,
-) -> Row<'_, Message, Renderer> {
+pub fn row<'a, Message, Renderer>(
+    children: impl Iterator<Item = Element<'a, Message, Renderer>>,
+) -> Row<'a, Message, Renderer>
+where
+    Renderer: core::Renderer,
+{
     Row::with_children(children)
 }
 

widget/src/lazy.rs

@@ -150,6 +150,13 @@ where
         self.with_element(|element| element.as_widget().height())
     }
 
+    fn size_hint(&self) -> Size<Length> {
+        Size {
+            width: Length::Shrink,
+            height: Length::Shrink,
+        }
+    }
+
     fn layout(
         &self,
         tree: &mut Tree,

widget/src/lazy/component.rs

@@ -252,6 +252,13 @@ where
         self.with_element(|element| element.as_widget().height())
     }
 
+    fn size_hint(&self) -> Size<Length> {
+        Size {
+            width: Length::Shrink,
+            height: Length::Shrink,
+        }
+    }
+
     fn layout(
         &self,
         tree: &mut Tree,

widget/src/row.rs

@@ -21,26 +21,31 @@ pub struct Row<'a, Message, Renderer = crate::Renderer> {
     children: Vec<Element<'a, Message, Renderer>>,
 }
 
-impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
+impl<'a, Message, Renderer> Row<'a, Message, Renderer>
+where
+    Renderer: crate::core::Renderer,
+{
     /// Creates an empty [`Row`].
     pub fn new() -> Self {
-        Self::with_children(Vec::new())
-    }
-
-    /// Creates a [`Row`] with the given elements.
-    pub fn with_children(
-        children: Vec<Element<'a, Message, Renderer>>,
-    ) -> Self {
         Row {
             spacing: 0.0,
             padding: Padding::ZERO,
             width: Length::Shrink,
             height: Length::Shrink,
             align_items: Alignment::Start,
-            children,
+            children: Vec::new(),
         }
     }
 
+    /// Creates a [`Row`] with the given elements.
+    pub fn with_children(
+        children: impl Iterator<Item = Element<'a, Message, Renderer>>,
+    ) -> Self {
+        children
+            .into_iter()
+            .fold(Self::new(), |column, element| column.push(element))
+    }
+
     /// Sets the horizontal spacing _between_ elements.
     ///
     /// Custom margins per element do not exist in iced. You should use this
@@ -80,12 +85,26 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
         mut self,
         child: impl Into<Element<'a, Message, Renderer>>,
     ) -> Self {
-        self.children.push(child.into());
+        let child = child.into();
+        let size = child.as_widget().size_hint();
+
+        if size.width.is_fill() {
+            self.width = Length::Fill;
+        }
+
+        if size.height.is_fill() {
+            self.height = Length::Fill;
+        }
+
+        self.children.push(child);
         self
     }
 }
 
-impl<'a, Message, Renderer> Default for Row<'a, Message, Renderer> {
+impl<'a, Message, Renderer> Default for Row<'a, Message, Renderer>
+where
+    Renderer: crate::core::Renderer,
+{
     fn default() -> Self {
         Self::new()
     }