Convert `Renderer::Theme` to generic `Widget` type

10 files changed, 125 insertions, 110 deletions

diff --git a/core/src/element.rs b/core/src/element.rs
index 4d4bfa36..fa07ad69 100644
--- a/core/src/element.rs
+++ b/core/src/element.rs
@@ -23,13 +23,13 @@ use std::borrow::Borrow;
 ///
 /// [built-in widget]: crate::widget
 #[allow(missing_debug_implementations)]
-pub struct Element<'a, Message, Renderer> {
-    widget: Box<dyn Widget<Message, Renderer> + 'a>,
+pub struct Element<'a, Message, Theme, Renderer> {
+    widget: Box<dyn Widget<Message, Theme, Renderer> + 'a>,
 }
 
-impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
+impl<'a, Message, Theme, Renderer> Element<'a, Message, Theme, Renderer> {
     /// Creates a new [`Element`] containing the given [`Widget`].
-    pub fn new(widget: impl Widget<Message, Renderer> + 'a) -> Self
+    pub fn new(widget: impl Widget<Message, Theme, Renderer> + 'a) -> Self
     where
         Renderer: crate::Renderer,
     {
@@ -39,12 +39,14 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     }
 
     /// Returns a reference to the [`Widget`] of the [`Element`],
-    pub fn as_widget(&self) -> &dyn Widget<Message, Renderer> {
+    pub fn as_widget(&self) -> &dyn Widget<Message, Theme, Renderer> {
         self.widget.as_ref()
     }
 
     /// Returns a mutable reference to the [`Widget`] of the [`Element`],
-    pub fn as_widget_mut(&mut self) -> &mut dyn Widget<Message, Renderer> {
+    pub fn as_widget_mut(
+        &mut self,
+    ) -> &mut dyn Widget<Message, Theme, Renderer> {
         self.widget.as_mut()
     }
 
@@ -100,7 +102,7 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     /// #     impl Counter {
     /// #         pub fn view(
     /// #             &self,
-    /// #         ) -> iced_core::Element<Message, iced_core::renderer::Null> {
+    /// #         ) -> iced_core::Element<Message, (), iced_core::renderer::Null> {
     /// #             unimplemented!()
     /// #         }
     /// #     }
@@ -126,7 +128,7 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     /// #
     /// #             pub fn push(
     /// #                 mut self,
-    /// #                 _: iced_core::Element<Message, iced_core::renderer::Null>,
+    /// #                 _: iced_core::Element<Message, (), iced_core::renderer::Null>,
     /// #             ) -> Self {
     /// #                 unimplemented!()
     /// #             }
@@ -155,7 +157,7 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     ///             Row::new().spacing(20),
     ///             |row, (index, counter)| {
     ///                 // We display the counter
-    ///                 let element: Element<counter::Message, Renderer> =
+    ///                 let element: Element<counter::Message, _, _> =
     ///                     counter.view().into();
     ///
     ///                 row.push(
@@ -210,9 +212,10 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     pub fn map<B>(
         self,
         f: impl Fn(Message) -> B + 'a,
-    ) -> Element<'a, B, Renderer>
+    ) -> Element<'a, B, Theme, Renderer>
     where
         Message: 'a,
+        Theme: 'a,
         Renderer: crate::Renderer + 'a,
         B: 'a,
     {
@@ -228,9 +231,10 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     pub fn explain<C: Into<Color>>(
         self,
         color: C,
-    ) -> Element<'a, Message, Renderer>
+    ) -> Element<'a, Message, Theme, Renderer>
     where
-        Message: 'static,
+        Message: 'a,
+        Theme: 'a,
         Renderer: crate::Renderer + 'a,
     {
         Element {
@@ -239,32 +243,34 @@ impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
     }
 }
 
-impl<'a, Message, Renderer> Borrow<dyn Widget<Message, Renderer> + 'a>
-    for Element<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer>
+    Borrow<dyn Widget<Message, Theme, Renderer> + 'a>
+    for Element<'a, Message, Theme, Renderer>
 {
-    fn borrow(&self) -> &(dyn Widget<Message, Renderer> + 'a) {
+    fn borrow(&self) -> &(dyn Widget<Message, Theme, Renderer> + 'a) {
         self.widget.borrow()
     }
 }
 
-impl<'a, Message, Renderer> Borrow<dyn Widget<Message, Renderer> + 'a>
-    for &Element<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer>
+    Borrow<dyn Widget<Message, Theme, Renderer> + 'a>
+    for &Element<'a, Message, Theme, Renderer>
 {
-    fn borrow(&self) -> &(dyn Widget<Message, Renderer> + 'a) {
+    fn borrow(&self) -> &(dyn Widget<Message, Theme, Renderer> + 'a) {
         self.widget.borrow()
     }
 }
 
-struct Map<'a, A, B, Renderer> {
-    widget: Box<dyn Widget<A, Renderer> + 'a>,
+struct Map<'a, A, B, Theme, Renderer> {
+    widget: Box<dyn Widget<A, Theme, Renderer> + 'a>,
     mapper: Box<dyn Fn(A) -> B + 'a>,
 }
 
-impl<'a, A, B, Renderer> Map<'a, A, B, Renderer> {
+impl<'a, A, B, Theme, Renderer> Map<'a, A, B, Theme, Renderer> {
     pub fn new<F>(
-        widget: Box<dyn Widget<A, Renderer> + 'a>,
+        widget: Box<dyn Widget<A, Theme, Renderer> + 'a>,
         mapper: F,
-    ) -> Map<'a, A, B, Renderer>
+    ) -> Map<'a, A, B, Theme, Renderer>
     where
         F: 'a + Fn(A) -> B,
     {
@@ -275,7 +281,8 @@ impl<'a, A, B, Renderer> Map<'a, A, B, Renderer> {
     }
 }
 
-impl<'a, A, B, Renderer> Widget<B, Renderer> for Map<'a, A, B, Renderer>
+impl<'a, A, B, Theme, Renderer> Widget<B, Theme, Renderer>
+    for Map<'a, A, B, Theme, Renderer>
 where
     Renderer: crate::Renderer + 'a,
     A: 'a,
@@ -408,7 +415,7 @@ where
         &self,
         tree: &Tree,
         renderer: &mut Renderer,
-        theme: &Renderer::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor: mouse::Cursor,
@@ -435,7 +442,7 @@ where
         tree: &'b mut Tree,
         layout: Layout<'_>,
         renderer: &Renderer,
-    ) -> Option<overlay::Element<'b, B, Renderer>> {
+    ) -> Option<overlay::Element<'b, B, Theme, Renderer>> {
         let mapper = &self.mapper;
 
         self.widget
@@ -444,22 +451,25 @@ where
     }
 }
 
-struct Explain<'a, Message, Renderer: crate::Renderer> {
-    element: Element<'a, Message, Renderer>,
+struct Explain<'a, Message, Theme, Renderer: crate::Renderer> {
+    element: Element<'a, Message, Theme, Renderer>,
     color: Color,
 }
 
-impl<'a, Message, Renderer> Explain<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> Explain<'a, Message, Theme, Renderer>
 where
     Renderer: crate::Renderer,
 {
-    fn new(element: Element<'a, Message, Renderer>, color: Color) -> Self {
+    fn new(
+        element: Element<'a, Message, Theme, Renderer>,
+        color: Color,
+    ) -> Self {
         Explain { element, color }
     }
 }
 
-impl<'a, Message, Renderer> Widget<Message, Renderer>
-    for Explain<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
+    for Explain<'a, Message, Theme, Renderer>
 where
     Renderer: crate::Renderer,
 {
@@ -524,7 +534,7 @@ where
         &self,
         state: &Tree,
         renderer: &mut Renderer,
-        theme: &Renderer::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor: mouse::Cursor,
@@ -578,7 +588,7 @@ where
         state: &'b mut Tree,
         layout: Layout<'_>,
         renderer: &Renderer,
-    ) -> Option<overlay::Element<'b, Message, Renderer>> {
+    ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
         self.element.widget.overlay(state, layout, renderer)
     }
 }
diff --git a/core/src/layout/flex.rs b/core/src/layout/flex.rs
index 3358ef3d..40bd7123 100644
--- a/core/src/layout/flex.rs
+++ b/core/src/layout/flex.rs
@@ -59,7 +59,7 @@ impl Axis {
 /// padding and alignment to the items as needed.
 ///
 /// It returns a new layout [`Node`].
-pub fn resolve<Message, Renderer>(
+pub fn resolve<Message, Theme, Renderer>(
     axis: Axis,
     renderer: &Renderer,
     limits: &Limits,
@@ -68,7 +68,7 @@ pub fn resolve<Message, Renderer>(
     padding: Padding,
     spacing: f32,
     align_items: Alignment,
-    items: &[Element<'_, Message, Renderer>],
+    items: &[Element<'_, Message, Theme, Renderer>],
     trees: &mut [widget::Tree],
 ) -> Node
 where
diff --git a/core/src/overlay.rs b/core/src/overlay.rs
index af10afee..6b8cf2a6 100644
--- a/core/src/overlay.rs
+++ b/core/src/overlay.rs
@@ -14,7 +14,7 @@ use crate::widget::Tree;
 use crate::{Clipboard, Layout, Point, Rectangle, Shell, Size, Vector};
 
 /// An interactive component that can be displayed on top of other widgets.
-pub trait Overlay<Message, Renderer>
+pub trait Overlay<Message, Theme, Renderer>
 where
     Renderer: crate::Renderer,
 {
@@ -36,7 +36,7 @@ where
     fn draw(
         &self,
         renderer: &mut Renderer,
-        theme: &Renderer::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor: mouse::Cursor,
@@ -106,7 +106,7 @@ where
         &'a mut self,
         _layout: Layout<'_>,
         _renderer: &Renderer,
-    ) -> Option<Element<'a, Message, Renderer>> {
+    ) -> Option<Element<'a, Message, Theme, Renderer>> {
         None
     }
 }
@@ -115,12 +115,12 @@ where
 ///
 /// This method will generally only be used by advanced users that are
 /// implementing the [`Widget`](crate::Widget) trait.
-pub fn from_children<'a, Message, Renderer>(
-    children: &'a mut [crate::Element<'_, Message, Renderer>],
+pub fn from_children<'a, Message, Theme, Renderer>(
+    children: &'a mut [crate::Element<'_, Message, Theme, Renderer>],
     tree: &'a mut Tree,
     layout: Layout<'_>,
     renderer: &Renderer,
-) -> Option<Element<'a, Message, Renderer>>
+) -> Option<Element<'a, Message, Theme, Renderer>>
 where
     Renderer: crate::Renderer,
 {
diff --git a/core/src/overlay/element.rs b/core/src/overlay/element.rs
index a279fe28..c34ab862 100644
--- a/core/src/overlay/element.rs
+++ b/core/src/overlay/element.rs
@@ -11,20 +11,20 @@ use std::any::Any;
 
 /// A generic [`Overlay`].
 #[allow(missing_debug_implementations)]
-pub struct Element<'a, Message, Renderer> {
+pub struct Element<'a, Message, Theme, Renderer> {
     position: Point,
     translation: Vector,
-    overlay: Box<dyn Overlay<Message, Renderer> + 'a>,
+    overlay: Box<dyn Overlay<Message, Theme, Renderer> + 'a>,
 }
 
-impl<'a, Message, Renderer> Element<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> Element<'a, Message, Theme, Renderer>
 where
     Renderer: crate::Renderer,
 {
     /// Creates a new [`Element`] containing the given [`Overlay`].
     pub fn new(
         position: Point,
-        overlay: Box<dyn Overlay<Message, Renderer> + 'a>,
+        overlay: Box<dyn Overlay<Message, Theme, Renderer> + 'a>,
     ) -> Self {
         Self {
             position,
@@ -46,9 +46,13 @@ where
     }
 
     /// Applies a transformation to the produced message of the [`Element`].
-    pub fn map<B>(self, f: &'a dyn Fn(Message) -> B) -> Element<'a, B, Renderer>
+    pub fn map<B>(
+        self,
+        f: &'a dyn Fn(Message) -> B,
+    ) -> Element<'a, B, Theme, Renderer>
     where
         Message: 'a,
+        Theme: 'a,
         Renderer: 'a,
         B: 'a,
     {
@@ -104,7 +108,7 @@ where
     pub fn draw(
         &self,
         renderer: &mut Renderer,
-        theme: &Renderer::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor: mouse::Cursor,
@@ -137,26 +141,27 @@ where
         &'b mut self,
         layout: Layout<'_>,
         renderer: &Renderer,
-    ) -> Option<Element<'b, Message, Renderer>> {
+    ) -> Option<Element<'b, Message, Theme, Renderer>> {
         self.overlay.overlay(layout, renderer)
     }
 }
 
-struct Map<'a, A, B, Renderer> {
-    content: Box<dyn Overlay<A, Renderer> + 'a>,
+struct Map<'a, A, B, Theme, Renderer> {
+    content: Box<dyn Overlay<A, Theme, Renderer> + 'a>,
     mapper: &'a dyn Fn(A) -> B,
 }
 
-impl<'a, A, B, Renderer> Map<'a, A, B, Renderer> {
+impl<'a, A, B, Theme, Renderer> Map<'a, A, B, Theme, Renderer> {
     pub fn new(
-        content: Box<dyn Overlay<A, Renderer> + 'a>,
+        content: Box<dyn Overlay<A, Theme, Renderer> + 'a>,
         mapper: &'a dyn Fn(A) -> B,
-    ) -> Map<'a, A, B, Renderer> {
+    ) -> Map<'a, A, B, Theme, Renderer> {
         Map { content, mapper }
     }
 }
 
-impl<'a, A, B, Renderer> Overlay<B, Renderer> for Map<'a, A, B, Renderer>
+impl<'a, A, B, Theme, Renderer> Overlay<B, Theme, Renderer>
+    for Map<'a, A, B, Theme, Renderer>
 where
     Renderer: crate::Renderer,
 {
@@ -269,7 +274,7 @@ where
     fn draw(
         &self,
         renderer: &mut Renderer,
-        theme: &Renderer::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor: mouse::Cursor,
@@ -290,7 +295,7 @@ where
         &'b mut self,
         layout: Layout<'_>,
         renderer: &Renderer,
-    ) -> Option<Element<'b, B, Renderer>> {
+    ) -> Option<Element<'b, B, Theme, Renderer>> {
         self.content
             .overlay(layout, renderer)
             .map(|overlay| overlay.map(self.mapper))
diff --git a/core/src/overlay/group.rs b/core/src/overlay/group.rs
index e1e9727a..4e54a002 100644
--- a/core/src/overlay/group.rs
+++ b/core/src/overlay/group.rs
@@ -11,14 +11,15 @@ use crate::{
 /// An [`Overlay`] container that displays multiple overlay [`overlay::Element`]
 /// children.
 #[allow(missing_debug_implementations)]
-pub struct Group<'a, Message, Renderer> {
-    children: Vec<overlay::Element<'a, Message, Renderer>>,
+pub struct Group<'a, Message, Theme, Renderer> {
+    children: Vec<overlay::Element<'a, Message, Theme, Renderer>>,
 }
 
-impl<'a, Message, Renderer> Group<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> Group<'a, Message, Theme, Renderer>
 where
-    Renderer: 'a + crate::Renderer,
     Message: 'a,
+    Theme: 'a,
+    Renderer: 'a + crate::Renderer,
 {
     /// Creates an empty [`Group`].
     pub fn new() -> Self {
@@ -27,7 +28,7 @@ where
 
     /// Creates a [`Group`] with the given elements.
     pub fn with_children(
-        children: Vec<overlay::Element<'a, Message, Renderer>>,
+        children: Vec<overlay::Element<'a, Message, Theme, Renderer>>,
     ) -> Self {
         Group { children }
     }
@@ -35,30 +36,32 @@ where
     /// Adds an [`overlay::Element`] to the [`Group`].
     pub fn push(
         mut self,
-        child: impl Into<overlay::Element<'a, Message, Renderer>>,
+        child: impl Into<overlay::Element<'a, Message, Theme, Renderer>>,
     ) -> Self {
         self.children.push(child.into());
         self
     }
 
     /// Turns the [`Group`] into an overlay [`overlay::Element`].
-    pub fn overlay(self) -> overlay::Element<'a, Message, Renderer> {
+    pub fn overlay(self) -> overlay::Element<'a, Message, Theme, Renderer> {
         overlay::Element::new(Point::ORIGIN, Box::new(self))
     }
 }
 
-impl<'a, Message, Renderer> Default for Group<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> Default
+    for Group<'a, Message, Theme, Renderer>
 where
-    Renderer: 'a + crate::Renderer,
     Message: 'a,
+    Theme: 'a,
+    Renderer: 'a + crate::Renderer,
 {
     fn default() -> Self {
         Self::with_children(Vec::new())
     }
 }
 
-impl<'a, Message, Renderer> Overlay<Message, Renderer>
-    for Group<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> Overlay<Message, Theme, Renderer>
+    for Group<'a, Message, Theme, Renderer>
 where
     Renderer: crate::Renderer,
 {
@@ -106,7 +109,7 @@ where
     fn draw(
         &self,
         renderer: &mut Renderer,
-        theme: &<Renderer as crate::Renderer>::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor: mouse::Cursor,
@@ -166,7 +169,7 @@ where
         &'b mut self,
         layout: Layout<'_>,
         renderer: &Renderer,
-    ) -> Option<overlay::Element<'b, Message, Renderer>> {
+    ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
         let children = self
             .children
             .iter_mut()
@@ -178,13 +181,14 @@ where
     }
 }
 
-impl<'a, Message, Renderer> From<Group<'a, Message, Renderer>>
-    for overlay::Element<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> From<Group<'a, Message, Theme, Renderer>>
+    for overlay::Element<'a, Message, Theme, Renderer>
 where
-    Renderer: 'a + crate::Renderer,
     Message: 'a,
+    Theme: 'a,
+    Renderer: 'a + crate::Renderer,
 {
-    fn from(group: Group<'a, Message, Renderer>) -> Self {
+    fn from(group: Group<'a, Message, Theme, Renderer>) -> Self {
         group.overlay()
     }
 }
diff --git a/core/src/renderer.rs b/core/src/renderer.rs
index a2a66aa8..0af74bb3 100644
--- a/core/src/renderer.rs
+++ b/core/src/renderer.rs
@@ -9,9 +9,6 @@ use crate::{Background, Border, Color, Rectangle, Shadow, Size, Vector};
 
 /// A component that can be used by widgets to draw themselves on a screen.
 pub trait Renderer: Sized {
-    /// The supported theme of the [`Renderer`].
-    type Theme;
-
     /// Draws the primitives recorded in the given closure in a new layer.
     ///
     /// The layer will clip its contents to the provided `bounds`.
diff --git a/core/src/renderer/null.rs b/core/src/renderer/null.rs
index 7accd34e..455daa42 100644
--- a/core/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -19,8 +19,6 @@ impl Null {
 }
 
 impl Renderer for Null {
-    type Theme = ();
-
     fn with_layer(&mut self, _bounds: Rectangle, _f: impl FnOnce(&mut Self)) {}
 
     fn with_translation(
diff --git a/core/src/widget.rs b/core/src/widget.rs
index 7f5632ae..d5e2ec6f 100644
--- a/core/src/widget.rs
+++ b/core/src/widget.rs
@@ -39,7 +39,7 @@ use crate::{Clipboard, Length, Rectangle, Shell, Size};
 /// [`geometry`]: https://github.com/iced-rs/iced/tree/0.10/examples/geometry
 /// [`lyon`]: https://github.com/nical/lyon
 /// [`iced_wgpu`]: https://github.com/iced-rs/iced/tree/0.10/wgpu
-pub trait Widget<Message, Renderer>
+pub trait Widget<Message, Theme, Renderer>
 where
     Renderer: crate::Renderer,
 {
@@ -70,7 +70,7 @@ where
         &self,
         tree: &Tree,
         renderer: &mut Renderer,
-        theme: &Renderer::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor: mouse::Cursor,
@@ -146,7 +146,7 @@ where
         _state: &'a mut Tree,
         _layout: Layout<'_>,
         _renderer: &Renderer,
-    ) -> Option<overlay::Element<'a, Message, Renderer>> {
+    ) -> Option<overlay::Element<'a, Message, Theme, Renderer>> {
         None
     }
 }
diff --git a/core/src/widget/text.rs b/core/src/widget/text.rs
index 4cabc7ce..0796c4e4 100644
--- a/core/src/widget/text.rs
+++ b/core/src/widget/text.rs
@@ -15,10 +15,10 @@ pub use text::{LineHeight, Shaping};
 
 /// A paragraph of text.
 #[allow(missing_debug_implementations)]
-pub struct Text<'a, Renderer>
+pub struct Text<'a, Theme, Renderer>
 where
+    Theme: StyleSheet,
     Renderer: text::Renderer,
-    Renderer::Theme: StyleSheet,
 {
     content: Cow<'a, str>,
     size: Option<Pixels>,
@@ -29,13 +29,13 @@ where
     vertical_alignment: alignment::Vertical,
     font: Option<Renderer::Font>,
     shaping: Shaping,
-    style: <Renderer::Theme as StyleSheet>::Style,
+    style: Theme::Style,
 }
 
-impl<'a, Renderer> Text<'a, Renderer>
+impl<'a, Theme, Renderer> Text<'a, Theme, Renderer>
 where
+    Theme: StyleSheet,
     Renderer: text::Renderer,
-    Renderer::Theme: StyleSheet,
 {
     /// Create a new fragment of [`Text`] with the given contents.
     pub fn new(content: impl Into<Cow<'a, str>>) -> Self {
@@ -74,10 +74,7 @@ where
     }
 
     /// Sets the style of the [`Text`].
-    pub fn style(
-        mut self,
-        style: impl Into<<Renderer::Theme as StyleSheet>::Style>,
-    ) -> Self {
+    pub fn style(mut self, style: impl Into<Theme::Style>) -> Self {
         self.style = style.into();
         self
     }
@@ -123,10 +120,11 @@ where
 #[derive(Debug, Default)]
 pub struct State<P: Paragraph>(P);
 
-impl<'a, Message, Renderer> Widget<Message, Renderer> for Text<'a, Renderer>
+impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
+    for Text<'a, Theme, Renderer>
 where
+    Theme: StyleSheet,
     Renderer: text::Renderer,
-    Renderer::Theme: StyleSheet,
 {
     fn tag(&self) -> tree::Tag {
         tree::Tag::of::<State<Renderer::Paragraph>>()
@@ -169,7 +167,7 @@ where
         &self,
         tree: &Tree,
         renderer: &mut Renderer,
-        theme: &Renderer::Theme,
+        theme: &Theme,
         style: &renderer::Style,
         layout: Layout<'_>,
         _cursor_position: mouse::Cursor,
@@ -272,21 +270,23 @@ pub fn draw<Renderer>(
     );
 }
 
-impl<'a, Message, Renderer> From<Text<'a, Renderer>>
-    for Element<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> From<Text<'a, Theme, Renderer>>
+    for Element<'a, Message, Theme, Renderer>
 where
+    Theme: StyleSheet + 'a,
     Renderer: text::Renderer + 'a,
-    Renderer::Theme: StyleSheet,
 {
-    fn from(text: Text<'a, Renderer>) -> Element<'a, Message, Renderer> {
+    fn from(
+        text: Text<'a, Theme, Renderer>,
+    ) -> Element<'a, Message, Theme, Renderer> {
         Element::new(text)
     }
 }
 
-impl<'a, Renderer> Clone for Text<'a, Renderer>
+impl<'a, Theme, Renderer> Clone for Text<'a, Theme, Renderer>
 where
+    Theme: StyleSheet,
     Renderer: text::Renderer,
-    Renderer::Theme: StyleSheet,
 {
     fn clone(&self) -> Self {
         Self {
@@ -304,20 +304,21 @@ where
     }
 }
 
-impl<'a, Renderer> From<&'a str> for Text<'a, Renderer>
+impl<'a, Theme, Renderer> From<&'a str> for Text<'a, Theme, Renderer>
 where
+    Theme: StyleSheet,
     Renderer: text::Renderer,
-    Renderer::Theme: StyleSheet,
 {
     fn from(content: &'a str) -> Self {
         Self::new(content)
     }
 }
 
-impl<'a, Message, Renderer> From<&'a str> for Element<'a, Message, Renderer>
+impl<'a, Message, Theme, Renderer> From<&'a str>
+    for Element<'a, Message, Theme, Renderer>
 where
+    Theme: StyleSheet + 'a,
     Renderer: text::Renderer + 'a,
-    Renderer::Theme: StyleSheet,
 {
     fn from(content: &'a str) -> Self {
         Text::from(content).into()
diff --git a/core/src/widget/tree.rs b/core/src/widget/tree.rs
index ff52b1ce..6b1a1309 100644
--- a/core/src/widget/tree.rs
+++ b/core/src/widget/tree.rs
@@ -31,8 +31,8 @@ impl Tree {
     }
 
     /// Creates a new [`Tree`] for the provided [`Widget`].
-    pub fn new<'a, Message, Renderer>(
-        widget: impl Borrow<dyn Widget<Message, Renderer> + 'a>,
+    pub fn new<'a, Message, Theme, Renderer>(
+        widget: impl Borrow<dyn Widget<Message, Theme, Renderer> + 'a>,
     ) -> Self
     where
         Renderer: crate::Renderer,
@@ -54,9 +54,9 @@ impl Tree {
     /// Otherwise, the whole [`Tree`] is recreated.
     ///
     /// [`Widget::diff`]: crate::Widget::diff
-    pub fn diff<'a, Message, Renderer>(
+    pub fn diff<'a, Message, Theme, Renderer>(
         &mut self,
-        new: impl Borrow<dyn Widget<Message, Renderer> + 'a>,
+        new: impl Borrow<dyn Widget<Message, Theme, Renderer> + 'a>,
     ) where
         Renderer: crate::Renderer,
     {
@@ -68,9 +68,9 @@ impl Tree {
     }
 
     /// Reconciles the children of the tree with the provided list of widgets.
-    pub fn diff_children<'a, Message, Renderer>(
+    pub fn diff_children<'a, Message, Theme, Renderer>(
         &mut self,
-        new_children: &[impl Borrow<dyn Widget<Message, Renderer> + 'a>],
+        new_children: &[impl Borrow<dyn Widget<Message, Theme, Renderer> + 'a>],
     ) where
         Renderer: crate::Renderer,
     {