4 files changed, 87 insertions, 10 deletions

diff --git a/native/src/renderer.rs b/native/src/renderer.rs
index 7a68ada4..284c95f6 100644
--- a/native/src/renderer.rs
+++ b/native/src/renderer.rs
@@ -21,14 +21,15 @@
 //! [`checkbox::Renderer`]: ../widget/checkbox/trait.Renderer.html
 
 mod debugger;
-#[cfg(debug_assertions)]
-mod null;
 mod windowed;
 
 pub use debugger::Debugger;
+pub use windowed::{Target, Windowed};
+
+#[cfg(debug_assertions)]
+mod null;
 #[cfg(debug_assertions)]
 pub use null::Null;
-pub use windowed::{Target, Windowed};
 
 use crate::{layout, Element};
 
@@ -43,6 +44,13 @@ pub trait Renderer: Sized {
     /// [`Renderer`]: trait.Renderer.html
     type Output;
 
+    /// The default styling attributes of the [`Renderer`].
+    ///
+    /// This type can be leveraged to implement style inheritance.
+    ///
+    /// [`Renderer`]: trait.Renderer.html
+    type Defaults: Default;
+
     /// Lays out the elements of a user interface.
     ///
     /// You should override this if you need to perform any operations before or
diff --git a/native/src/renderer/debugger.rs b/native/src/renderer/debugger.rs
index 4cc50661..30f3d9a0 100644
--- a/native/src/renderer/debugger.rs
+++ b/native/src/renderer/debugger.rs
@@ -17,6 +17,7 @@ pub trait Debugger: super::Renderer {
     /// [`Element::explain`]: struct.Element.html#method.explain
     fn explain<Message>(
         &mut self,
+        defaults: &Self::Defaults,
         widget: &dyn Widget<Message, Self>,
         layout: Layout<'_>,
         cursor_position: Point,
diff --git a/native/src/renderer/null.rs b/native/src/renderer/null.rs
index 43076d61..df261cdc 100644
--- a/native/src/renderer/null.rs
+++ b/native/src/renderer/null.rs
@@ -1,20 +1,33 @@
 use crate::{
-    button, checkbox, column, radio, row, scrollable, text, text_input,
-    Background, Color, Element, Font, HorizontalAlignment, Layout, Point,
+    button, checkbox, column, progress_bar, radio, row, scrollable, slider,
+    text, text_input, Color, Element, Font, HorizontalAlignment, Layout, Point,
     Rectangle, Renderer, Size, VerticalAlignment,
 };
 
 /// A renderer that does nothing.
+///
+/// It can be useful if you are writing tests!
 #[derive(Debug, Clone, Copy)]
 pub struct Null;
 
+impl Null {
+    /// Creates a new [`Null`] renderer.
+    ///
+    /// [`Null`]: struct.Null.html
+    pub fn new() -> Null {
+        Null
+    }
+}
+
 impl Renderer for Null {
     type Output = ();
+    type Defaults = ();
 }
 
 impl column::Renderer for Null {
     fn draw<Message>(
         &mut self,
+        _defaults: &Self::Defaults,
         _content: &[Element<'_, Message, Self>],
         _layout: Layout<'_>,
         _cursor_position: Point,
@@ -25,6 +38,7 @@ impl column::Renderer for Null {
 impl row::Renderer for Null {
     fn draw<Message>(
         &mut self,
+        _defaults: &Self::Defaults,
         _content: &[Element<'_, Message, Self>],
         _layout: Layout<'_>,
         _cursor_position: Point,
@@ -49,6 +63,7 @@ impl text::Renderer for Null {
 
     fn draw(
         &mut self,
+        _defaults: &Self::Defaults,
         _bounds: Rectangle,
         _content: &str,
         _size: u16,
@@ -61,6 +76,8 @@ impl text::Renderer for Null {
 }
 
 impl scrollable::Renderer for Null {
+    type Style = ();
+
     fn scrollbar(
         &self,
         _bounds: Rectangle,
@@ -79,12 +96,15 @@ impl scrollable::Renderer for Null {
         _is_mouse_over_scrollbar: bool,
         _scrollbar: Option<scrollable::Scrollbar>,
         _offset: u32,
+        _style: &Self::Style,
         _content: Self::Output,
     ) {
     }
 }
 
 impl text_input::Renderer for Null {
+    type Style = ();
+
     fn default_size(&self) -> u16 {
         20
     }
@@ -112,24 +132,31 @@ impl text_input::Renderer for Null {
         _placeholder: &str,
         _value: &text_input::Value,
         _state: &text_input::State,
+        _style: &Self::Style,
     ) -> Self::Output {
     }
 }
 
 impl button::Renderer for Null {
-    fn draw(
+    type Style = ();
+
+    fn draw<Message>(
         &mut self,
+        _defaults: &Self::Defaults,
         _bounds: Rectangle,
         _cursor_position: Point,
+        _is_disabled: bool,
         _is_pressed: bool,
-        _background: Option<Background>,
-        _border_radius: u16,
-        _content: Self::Output,
+        _style: &Self::Style,
+        _content: &Element<'_, Message, Self>,
+        _content_layout: Layout<'_>,
     ) -> Self::Output {
     }
 }
 
 impl radio::Renderer for Null {
+    type Style = ();
+
     fn default_size(&self) -> u32 {
         20
     }
@@ -140,11 +167,14 @@ impl radio::Renderer for Null {
         _is_selected: bool,
         _is_mouse_over: bool,
         _label: Self::Output,
+        _style: &Self::Style,
     ) {
     }
 }
 
 impl checkbox::Renderer for Null {
+    type Style = ();
+
     fn default_size(&self) -> u32 {
         20
     }
@@ -155,6 +185,41 @@ impl checkbox::Renderer for Null {
         _is_checked: bool,
         _is_mouse_over: bool,
         _label: Self::Output,
+        _style: &Self::Style,
+    ) {
+    }
+}
+
+impl slider::Renderer for Null {
+    type Style = ();
+
+    fn height(&self) -> u32 {
+        30
+    }
+
+    fn draw(
+        &mut self,
+        _bounds: Rectangle,
+        _cursor_position: Point,
+        _range: std::ops::RangeInclusive<f32>,
+        _value: f32,
+        _is_dragging: bool,
+        _style_sheet: &Self::Style,
+    ) {
+    }
+}
+
+impl progress_bar::Renderer for Null {
+    type Style = ();
+
+    const DEFAULT_HEIGHT: u16 = 30;
+
+    fn draw(
+        &self,
+        _bounds: Rectangle,
+        _range: std::ops::RangeInclusive<f32>,
+        _value: f32,
+        _style: &Self::Style,
     ) {
     }
 }
diff --git a/native/src/renderer/windowed.rs b/native/src/renderer/windowed.rs
index 813a03f2..ee020ab1 100644
--- a/native/src/renderer/windowed.rs
+++ b/native/src/renderer/windowed.rs
@@ -4,13 +4,16 @@ use raw_window_handle::HasRawWindowHandle;
 
 /// A renderer that can target windows.
 pub trait Windowed: super::Renderer + Sized {
+    /// The settings of the renderer.
+    type Settings: Default;
+
     /// The type of target.
     type Target: Target<Renderer = Self>;
 
     /// Creates a new [`Windowed`] renderer.
     ///
     /// [`Windowed`]: trait.Windowed.html
-    fn new() -> Self;
+    fn new(settings: Self::Settings) -> Self;
 
     /// Performs the drawing operations described in the output on the given
     /// target.