Draft first-class `Theme` support

RFC: https://github.com/iced-rs/rfcs/pull/6

5 files changed, 53 insertions, 36 deletions

diff --git a/graphics/src/renderer.rs b/graphics/src/renderer.rs
index cb31ea5f..3c19fbfb 100644
--- a/graphics/src/renderer.rs
+++ b/graphics/src/renderer.rs
@@ -10,19 +10,23 @@ use iced_native::{Background, Element, Font, Point, Rectangle, Size};
 
 pub use iced_native::renderer::Style;
 
+use std::marker::PhantomData;
+
 /// A backend-agnostic renderer that supports all the built-in widgets.
 #[derive(Debug)]
-pub struct Renderer<B: Backend> {
+pub struct Renderer<B: Backend, Theme> {
     backend: B,
     primitives: Vec<Primitive>,
+    theme: PhantomData<Theme>,
 }
 
-impl<B: Backend> Renderer<B> {
+impl<B: Backend, T> Renderer<B, T> {
     /// Creates a new [`Renderer`] from the given [`Backend`].
     pub fn new(backend: B) -> Self {
         Self {
             backend,
             primitives: Vec::new(),
+            theme: PhantomData,
         }
     }
 
@@ -43,10 +47,12 @@ impl<B: Backend> Renderer<B> {
     }
 }
 
-impl<B> iced_native::Renderer for Renderer<B>
+impl<B, T> iced_native::Renderer for Renderer<B, T>
 where
     B: Backend,
 {
+    type Theme = T;
+
     fn layout<'a, Message>(
         &mut self,
         element: &Element<'a, Message, Self>,
@@ -114,7 +120,7 @@ where
     }
 }
 
-impl<B> text::Renderer for Renderer<B>
+impl<B, T> text::Renderer for Renderer<B, T>
 where
     B: Backend + backend::Text,
 {
@@ -171,7 +177,7 @@ where
     }
 }
 
-impl<B> image::Renderer for Renderer<B>
+impl<B, T> image::Renderer for Renderer<B, T>
 where
     B: Backend + backend::Image,
 {
@@ -186,7 +192,7 @@ where
     }
 }
 
-impl<B> svg::Renderer for Renderer<B>
+impl<B, T> svg::Renderer for Renderer<B, T>
 where
     B: Backend + backend::Svg,
 {
diff --git a/graphics/src/widget/canvas.rs b/graphics/src/widget/canvas.rs
index 23444b2b..0de08b01 100644
--- a/graphics/src/widget/canvas.rs
+++ b/graphics/src/widget/canvas.rs
@@ -127,7 +127,7 @@ impl<Message, P: Program<Message>> Canvas<Message, P> {
     }
 }
 
-impl<Message, P, B> Widget<Message, Renderer<B>> for Canvas<Message, P>
+impl<Message, P, B, T> Widget<Message, Renderer<B, T>> for Canvas<Message, P>
 where
     P: Program<Message>,
     B: Backend,
@@ -142,7 +142,7 @@ where
 
     fn layout(
         &self,
-        _renderer: &Renderer<B>,
+        _renderer: &Renderer<B, T>,
         limits: &layout::Limits,
     ) -> layout::Node {
         let limits = limits.width(self.width).height(self.height);
@@ -156,7 +156,7 @@ where
         event: iced_native::Event,
         layout: Layout<'_>,
         cursor_position: Point,
-        _renderer: &Renderer<B>,
+        _renderer: &Renderer<B, T>,
         _clipboard: &mut dyn Clipboard,
         shell: &mut Shell<'_, Message>,
     ) -> event::Status {
@@ -193,7 +193,7 @@ where
         layout: Layout<'_>,
         cursor_position: Point,
         _viewport: &Rectangle,
-        _renderer: &Renderer<B>,
+        _renderer: &Renderer<B, T>,
     ) -> mouse::Interaction {
         let bounds = layout.bounds();
         let cursor = Cursor::from_window_position(cursor_position);
@@ -203,7 +203,8 @@ where
 
     fn draw(
         &self,
-        renderer: &mut Renderer<B>,
+        renderer: &mut Renderer<B, T>,
+        _theme: &T,
         _style: &renderer::Style,
         layout: Layout<'_>,
         cursor_position: Point,
@@ -233,14 +234,16 @@ where
     }
 }
 
-impl<'a, Message, P, B> From<Canvas<Message, P>>
-    for Element<'a, Message, Renderer<B>>
+impl<'a, Message, P, B, T> From<Canvas<Message, P>>
+    for Element<'a, Message, Renderer<B, T>>
 where
     Message: 'static,
     P: Program<Message> + 'a,
     B: Backend,
 {
-    fn from(canvas: Canvas<Message, P>) -> Element<'a, Message, Renderer<B>> {
+    fn from(
+        canvas: Canvas<Message, P>,
+    ) -> Element<'a, Message, Renderer<B, T>> {
         Element::new(canvas)
     }
 }
diff --git a/graphics/src/widget/pure/canvas.rs b/graphics/src/widget/pure/canvas.rs
index 2e3e7ede..d53b20f6 100644
--- a/graphics/src/widget/pure/canvas.rs
+++ b/graphics/src/widget/pure/canvas.rs
@@ -103,7 +103,7 @@ where
     }
 }
 
-impl<Message, P, B> Widget<Message, Renderer<B>> for Canvas<Message, P>
+impl<Message, P, B, T> Widget<Message, Renderer<B, T>> for Canvas<Message, P>
 where
     P: Program<Message>,
     B: Backend,
@@ -126,7 +126,7 @@ where
 
     fn layout(
         &self,
-        _renderer: &Renderer<B>,
+        _renderer: &Renderer<B, T>,
         limits: &layout::Limits,
     ) -> layout::Node {
         let limits = limits.width(self.width).height(self.height);
@@ -141,7 +141,7 @@ where
         event: iced_native::Event,
         layout: Layout<'_>,
         cursor_position: Point,
-        _renderer: &Renderer<B>,
+        _renderer: &Renderer<B, T>,
         _clipboard: &mut dyn Clipboard,
         shell: &mut Shell<'_, Message>,
     ) -> event::Status {
@@ -181,7 +181,7 @@ where
         layout: Layout<'_>,
         cursor_position: Point,
         _viewport: &Rectangle,
-        _renderer: &Renderer<B>,
+        _renderer: &Renderer<B, T>,
     ) -> mouse::Interaction {
         let bounds = layout.bounds();
         let cursor = Cursor::from_window_position(cursor_position);
@@ -193,7 +193,8 @@ where
     fn draw(
         &self,
         tree: &Tree,
-        renderer: &mut Renderer<B>,
+        renderer: &mut Renderer<B, T>,
+        _theme: &T,
         _style: &renderer::Style,
         layout: Layout<'_>,
         cursor_position: Point,
@@ -224,14 +225,16 @@ where
     }
 }
 
-impl<'a, Message, P, B> From<Canvas<Message, P>>
-    for Element<'a, Message, Renderer<B>>
+impl<'a, Message, P, B, T> From<Canvas<Message, P>>
+    for Element<'a, Message, Renderer<B, T>>
 where
     Message: 'a,
     P: Program<Message> + 'a,
     B: Backend,
 {
-    fn from(canvas: Canvas<Message, P>) -> Element<'a, Message, Renderer<B>> {
+    fn from(
+        canvas: Canvas<Message, P>,
+    ) -> Element<'a, Message, Renderer<B, T>> {
         Element::new(canvas)
     }
 }
diff --git a/graphics/src/widget/pure/qr_code.rs b/graphics/src/widget/pure/qr_code.rs
index 9d517374..23a8ceb6 100644
--- a/graphics/src/widget/pure/qr_code.rs
+++ b/graphics/src/widget/pure/qr_code.rs
@@ -9,24 +9,24 @@ use iced_native::{Length, Point, Rectangle};
 use iced_pure::widget::tree::Tree;
 use iced_pure::{Element, Widget};
 
-impl<'a, Message, B> Widget<Message, Renderer<B>> for QRCode<'a>
+impl<'a, Message, B, T> Widget<Message, Renderer<B, T>> for QRCode<'a>
 where
     B: Backend,
 {
     fn width(&self) -> Length {
-        <Self as iced_native::Widget<Message, Renderer<B>>>::width(self)
+        <Self as iced_native::Widget<Message, Renderer<B, T>>>::width(self)
     }
 
     fn height(&self) -> Length {
-        <Self as iced_native::Widget<Message, Renderer<B>>>::height(self)
+        <Self as iced_native::Widget<Message, Renderer<B, T>>>::height(self)
     }
 
     fn layout(
         &self,
-        renderer: &Renderer<B>,
+        renderer: &Renderer<B, T>,
         limits: &layout::Limits,
     ) -> layout::Node {
-        <Self as iced_native::Widget<Message, Renderer<B>>>::layout(
+        <Self as iced_native::Widget<Message, Renderer<B, T>>>::layout(
             self, renderer, limits,
         )
     }
@@ -34,15 +34,17 @@ where
     fn draw(
         &self,
         _tree: &Tree,
-        renderer: &mut Renderer<B>,
+        renderer: &mut Renderer<B, T>,
+        theme: &T,
         style: &renderer::Style,
         layout: Layout<'_>,
         cursor_position: Point,
         viewport: &Rectangle,
     ) {
-        <Self as iced_native::Widget<Message, Renderer<B>>>::draw(
+        <Self as iced_native::Widget<Message, Renderer<B, T>>>::draw(
             self,
             renderer,
+            theme,
             style,
             layout,
             cursor_position,
@@ -51,11 +53,12 @@ where
     }
 }
 
-impl<'a, Message, B> Into<Element<'a, Message, Renderer<B>>> for QRCode<'a>
+impl<'a, Message, B, T> Into<Element<'a, Message, Renderer<B, T>>>
+    for QRCode<'a>
 where
     B: Backend,
 {
-    fn into(self) -> Element<'a, Message, Renderer<B>> {
+    fn into(self) -> Element<'a, Message, Renderer<B, T>> {
         Element::new(self)
     }
 }
diff --git a/graphics/src/widget/qr_code.rs b/graphics/src/widget/qr_code.rs
index 907794b7..1eb862ba 100644
--- a/graphics/src/widget/qr_code.rs
+++ b/graphics/src/widget/qr_code.rs
@@ -47,7 +47,7 @@ impl<'a> QRCode<'a> {
     }
 }
 
-impl<'a, Message, B> Widget<Message, Renderer<B>> for QRCode<'a>
+impl<'a, Message, B, T> Widget<Message, Renderer<B, T>> for QRCode<'a>
 where
     B: Backend,
 {
@@ -61,7 +61,7 @@ where
 
     fn layout(
         &self,
-        _renderer: &Renderer<B>,
+        _renderer: &Renderer<B, T>,
         _limits: &layout::Limits,
     ) -> layout::Node {
         let side_length = (self.state.width + 2 * QUIET_ZONE) as f32
@@ -75,7 +75,8 @@ where
 
     fn draw(
         &self,
-        renderer: &mut Renderer<B>,
+        renderer: &mut Renderer<B, T>,
+        _theme: &T,
         _style: &renderer::Style,
         layout: Layout<'_>,
         _cursor_position: Point,
@@ -127,11 +128,12 @@ where
     }
 }
 
-impl<'a, Message, B> Into<Element<'a, Message, Renderer<B>>> for QRCode<'a>
+impl<'a, Message, B, T> Into<Element<'a, Message, Renderer<B, T>>>
+    for QRCode<'a>
 where
     B: Backend,
 {
-    fn into(self) -> Element<'a, Message, Renderer<B>> {
+    fn into(self) -> Element<'a, Message, Renderer<B, T>> {
         Element::new(self)
     }
 }