Add `Style` variant support to `application::StyleSheet`

11 files changed, 148 insertions, 43 deletions

diff --git a/examples/integration_opengl/src/main.rs b/examples/integration_opengl/src/main.rs
index cd46e9fd..1a78a493 100644
--- a/examples/integration_opengl/src/main.rs
+++ b/examples/integration_opengl/src/main.rs
@@ -12,7 +12,8 @@ use iced_glow::glow;
 use iced_glow::{Backend, Renderer, Settings, Viewport};
 use iced_glutin::conversion;
 use iced_glutin::glutin;
-use iced_glutin::{program, Clipboard, Debug, Size};
+use iced_glutin::renderer;
+use iced_glutin::{program, Clipboard, Color, Debug, Size};
 
 pub fn main() {
     env_logger::init();
@@ -126,6 +127,9 @@ pub fn main() {
                         ),
                         &mut renderer,
                         &iced_glow::Theme::Dark,
+                        &renderer::Style {
+                            text_color: Color::WHITE,
+                        },
                         &mut clipboard,
                         &mut debug,
                     );
diff --git a/examples/integration_wgpu/src/main.rs b/examples/integration_wgpu/src/main.rs
index 1108b55d..3d27a0f0 100644
--- a/examples/integration_wgpu/src/main.rs
+++ b/examples/integration_wgpu/src/main.rs
@@ -5,7 +5,10 @@ use controls::Controls;
 use scene::Scene;
 
 use iced_wgpu::{wgpu, Backend, Renderer, Settings, Viewport};
-use iced_winit::{conversion, futures, program, winit, Clipboard, Debug, Size};
+use iced_winit::{
+    conversion, futures, program, renderer, winit, Clipboard, Color, Debug,
+    Size,
+};
 
 use winit::{
     dpi::PhysicalPosition,
@@ -189,6 +192,7 @@ pub fn main() {
                         ),
                         &mut renderer,
                         &iced_wgpu::Theme::Dark,
+                        &renderer::Style { text_color: Color::WHITE },
                         &mut clipboard,
                         &mut debug,
                     );
diff --git a/examples/solar_system/src/main.rs b/examples/solar_system/src/main.rs
index 7e0e06b0..cee9a02f 100644
--- a/examples/solar_system/src/main.rs
+++ b/examples/solar_system/src/main.rs
@@ -6,13 +6,15 @@
 //! Inspired by the example found in the MDN docs[1].
 //!
 //! [1]: https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Basic_animations#An_animated_solar_system
+use iced::application;
 use iced::canvas::{self, Cursor, Path, Stroke};
 use iced::executor;
+use iced::theme::{self, Theme};
 use iced::time;
 use iced::window;
 use iced::{
     Application, Canvas, Color, Command, Element, Length, Point, Rectangle,
-    Settings, Size, Subscription, Theme, Vector,
+    Settings, Size, Subscription, Vector,
 };
 
 use std::time::Instant;
@@ -77,6 +79,13 @@ impl Application for SolarSystem {
     fn theme(&self) -> Theme {
         Theme::Dark
     }
+
+    fn style(&self) -> theme::Application {
+        theme::Application::Custom(|_theme| application::Appearance {
+            background_color: Color::BLACK,
+            text_color: Color::WHITE,
+        })
+    }
 }
 
 #[derive(Debug)]
diff --git a/glutin/src/application.rs b/glutin/src/application.rs
index a222036a..dddf0067 100644
--- a/glutin/src/application.rs
+++ b/glutin/src/application.rs
@@ -10,6 +10,7 @@ use iced_winit::application;
 use iced_winit::conversion;
 use iced_winit::futures;
 use iced_winit::futures::channel::mpsc;
+use iced_winit::renderer;
 use iced_winit::user_interface;
 use iced_winit::{Clipboard, Debug, Proxy, Settings};
 
@@ -212,7 +213,6 @@ async fn run_instance<A, E, C>(
 
     let mut state = application::State::new(&application, context.window());
     let mut viewport_version = state.viewport_version();
-    let mut theme = application.theme();
 
     let mut user_interface =
         ManuallyDrop::new(application::build_user_interface(
@@ -278,7 +278,6 @@ async fn run_instance<A, E, C>(
 
                     let should_exit = application.should_exit();
 
-                    theme = application.theme();
                     user_interface =
                         ManuallyDrop::new(application::build_user_interface(
                             &mut application,
@@ -296,7 +295,10 @@ async fn run_instance<A, E, C>(
                 debug.draw_started();
                 let new_mouse_interaction = user_interface.draw(
                     &mut renderer,
-                    &theme,
+                    state.theme(),
+                    &renderer::Style {
+                        text_color: state.text_color(),
+                    },
                     state.cursor_position(),
                 );
                 debug.draw_finished();
@@ -352,7 +354,10 @@ async fn run_instance<A, E, C>(
                     debug.draw_started();
                     let new_mouse_interaction = user_interface.draw(
                         &mut renderer,
-                        &theme,
+                        state.theme(),
+                        &renderer::Style {
+                            text_color: state.text_color(),
+                        },
                         state.cursor_position(),
                     );
                     debug.draw_finished();
@@ -380,7 +385,7 @@ async fn run_instance<A, E, C>(
                 compositor.present(
                     &mut renderer,
                     state.viewport(),
-                    theme.background_color(),
+                    state.background_color(),
                     &debug.overlay(),
                 );
 
diff --git a/native/src/program/state.rs b/native/src/program/state.rs
index c881a64f..7ec2a04f 100644
--- a/native/src/program/state.rs
+++ b/native/src/program/state.rs
@@ -1,5 +1,6 @@
 use crate::application;
 use crate::mouse;
+use crate::renderer;
 use crate::user_interface::{self, UserInterface};
 use crate::{Clipboard, Command, Debug, Event, Point, Program, Size};
 
@@ -89,6 +90,7 @@ where
         cursor_position: Point,
         renderer: &mut P::Renderer,
         theme: &<P::Renderer as crate::Renderer>::Theme,
+        style: &renderer::Style,
         clipboard: &mut dyn Clipboard,
         debug: &mut Debug,
     ) -> Option<Command<P::Message>> {
@@ -118,7 +120,7 @@ where
         if messages.is_empty() {
             debug.draw_started();
             self.mouse_interaction =
-                user_interface.draw(renderer, theme, cursor_position);
+                user_interface.draw(renderer, theme, style, cursor_position);
             debug.draw_finished();
 
             self.cache = Some(user_interface.into_cache());
@@ -150,7 +152,7 @@ where
 
             debug.draw_started();
             self.mouse_interaction =
-                user_interface.draw(renderer, theme, cursor_position);
+                user_interface.draw(renderer, theme, style, cursor_position);
             debug.draw_finished();
 
             self.cache = Some(user_interface.into_cache());
diff --git a/native/src/user_interface.rs b/native/src/user_interface.rs
index d682a880..97a004e7 100644
--- a/native/src/user_interface.rs
+++ b/native/src/user_interface.rs
@@ -303,8 +303,10 @@ where
     /// [completing the last example](#example-1):
     ///
     /// ```no_run
-    /// use iced_native::{clipboard, Size, Point, Theme};
+    /// use iced_native::clipboard;
+    /// use iced_native::renderer;
     /// use iced_native::user_interface::{self, UserInterface};
+    /// use iced_native::{Size, Point, Theme};
     /// use iced_wgpu::Renderer;
     ///
     /// # mod iced_wgpu {
@@ -351,7 +353,7 @@ where
     ///     );
     ///
     ///     // Draw the user interface
-    ///     let mouse_cursor = user_interface.draw(&mut renderer, &Theme::default(), cursor_position);
+    ///     let mouse_cursor = user_interface.draw(&mut renderer, &Theme::default(), &renderer::Style::default(), cursor_position);
     ///
     ///     cache = user_interface.into_cache();
     ///
@@ -367,6 +369,7 @@ where
         &mut self,
         renderer: &mut Renderer,
         theme: &Renderer::Theme,
+        style: &renderer::Style,
         cursor_position: Point,
     ) -> mouse::Interaction {
         // TODO: Move to shell level (?)
@@ -399,12 +402,7 @@ where
         self.root.widget.draw(
             renderer,
             theme,
-            &renderer::Style {
-                text_color: {
-                    use application::StyleSheet;
-                    theme.text_color()
-                },
-            },
+            style,
             Layout::new(&self.base),
             base_cursor,
             &viewport,
@@ -446,7 +444,7 @@ where
                         overlay.draw(
                             renderer,
                             theme,
-                            &renderer::Style::default(),
+                            style,
                             Layout::new(layout),
                             cursor_position,
                         );
diff --git a/src/application.rs b/src/application.rs
index b7c8cf9f..d4297eea 100644
--- a/src/application.rs
+++ b/src/application.rs
@@ -1,7 +1,7 @@
 use crate::window;
 use crate::{Command, Element, Executor, Settings, Subscription};
 
-pub use iced_native::application::StyleSheet;
+pub use iced_native::application::{Appearance, StyleSheet};
 
 /// An interactive cross-platform application.
 ///
@@ -141,10 +141,20 @@ pub trait Application: Sized {
     fn view(&mut self) -> Element<'_, Self::Message, Self::Theme>;
 
     /// Returns the current [`Theme`] of the [`Application`].
+    ///
+    /// [`Theme`]: Self::Theme
     fn theme(&self) -> Self::Theme {
         Self::Theme::default()
     }
 
+    /// Returns the current [`Style`] of the [`Theme`].
+    ///
+    /// [`Style`]: <Self::Theme as StyleSheet>::Style
+    /// [`Theme`]: Self::Theme
+    fn style(&self) -> <Self::Theme as StyleSheet>::Style {
+        <Self::Theme as StyleSheet>::Style::default()
+    }
+
     /// Returns the event [`Subscription`] for the current state of the
     /// application.
     ///
@@ -260,6 +270,10 @@ where
         self.0.theme()
     }
 
+    fn style(&self) -> <A::Theme as StyleSheet>::Style {
+        self.0.style()
+    }
+
     fn mode(&self) -> iced_winit::Mode {
         match self.0.mode() {
             window::Mode::Windowed => iced_winit::Mode::Windowed,
diff --git a/style/src/application.rs b/style/src/application.rs
index 4aa950fb..d48c6a34 100644
--- a/style/src/application.rs
+++ b/style/src/application.rs
@@ -1,7 +1,13 @@
 use iced_core::Color;
 
 pub trait StyleSheet {
-    fn background_color(&self) -> Color;
+    type Style: Default + Copy;
 
-    fn text_color(&self) -> Color;
+    fn appearance(&self, style: Self::Style) -> Appearance;
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Appearance {
+    pub background_color: Color,
+    pub text_color: Color,
 }
diff --git a/style/src/theme.rs b/style/src/theme.rs
index 0bae671e..70b32edf 100644
--- a/style/src/theme.rs
+++ b/style/src/theme.rs
@@ -48,17 +48,31 @@ impl Default for Theme {
     }
 }
 
-impl application::StyleSheet for Theme {
-    fn background_color(&self) -> Color {
-        let palette = self.extended_palette();
+#[derive(Debug, Clone, Copy)]
+pub enum Application {
+    Default,
+    Custom(fn(Theme) -> application::Appearance),
+}
 
-        palette.background.base.color
+impl Default for Application {
+    fn default() -> Self {
+        Self::Default
     }
+}
 
-    fn text_color(&self) -> Color {
+impl application::StyleSheet for Theme {
+    type Style = Application;
+
+    fn appearance(&self, style: Self::Style) -> application::Appearance {
         let palette = self.extended_palette();
 
-        palette.background.base.text
+        match style {
+            Application::Default => application::Appearance {
+                background_color: palette.background.base.color,
+                text_color: palette.background.base.text,
+            },
+            Application::Custom(f) => f(*self),
+        }
     }
 }
 
diff --git a/winit/src/application.rs b/winit/src/application.rs
index c7905c60..9c7dd74e 100644
--- a/winit/src/application.rs
+++ b/winit/src/application.rs
@@ -6,6 +6,7 @@ pub use state::State;
 use crate::clipboard::{self, Clipboard};
 use crate::conversion;
 use crate::mouse;
+use crate::renderer;
 use crate::{
     Command, Debug, Error, Executor, Mode, Proxy, Runtime, Settings, Size,
     Subscription,
@@ -18,7 +19,7 @@ use iced_graphics::window;
 use iced_native::program::Program;
 use iced_native::user_interface::{self, UserInterface};
 
-pub use iced_native::application::StyleSheet;
+pub use iced_native::application::{Appearance, StyleSheet};
 
 use std::mem::ManuallyDrop;
 
@@ -33,7 +34,10 @@ use std::mem::ManuallyDrop;
 ///
 /// When using an [`Application`] with the `debug` feature enabled, a debug view
 /// can be toggled by pressing `F12`.
-pub trait Application: Program {
+pub trait Application: Program
+where
+    <Self::Renderer as crate::Renderer>::Theme: StyleSheet,
+{
     /// The data needed to initialize your [`Application`].
     type Flags;
 
@@ -54,7 +58,14 @@ pub trait Application: Program {
     fn title(&self) -> String;
 
     /// Returns the current [`Theme`] of the [`Application`].
-    fn theme(&self) -> <Self::Renderer as iced_native::Renderer>::Theme;
+    fn theme(&self) -> <Self::Renderer as crate::Renderer>::Theme;
+
+    /// Returns the [`Style`] variation of the [`Theme`].
+    fn style(
+        &self,
+    ) -> <<Self::Renderer as crate::Renderer>::Theme as StyleSheet>::Style {
+        Default::default()
+    }
 
     /// Returns the event `Subscription` for the current state of the
     /// application.
@@ -110,7 +121,7 @@ where
     A: Application + 'static,
     E: Executor + 'static,
     C: window::Compositor<Renderer = A::Renderer> + 'static,
-    <A::Renderer as iced_native::Renderer>::Theme: StyleSheet,
+    <A::Renderer as crate::Renderer>::Theme: StyleSheet,
 {
     use futures::task;
     use futures::Future;
@@ -246,7 +257,7 @@ async fn run_instance<A, E, C>(
     A: Application + 'static,
     E: Executor + 'static,
     C: window::Compositor<Renderer = A::Renderer> + 'static,
-    <A::Renderer as iced_native::Renderer>::Theme: StyleSheet,
+    <A::Renderer as crate::Renderer>::Theme: StyleSheet,
 {
     use iced_futures::futures::stream::StreamExt;
     use winit::event;
@@ -255,7 +266,6 @@ async fn run_instance<A, E, C>(
 
     let mut state = State::new(&application, &window);
     let mut viewport_version = state.viewport_version();
-    let mut theme = application.theme();
 
     let physical_size = state.physical_size();
 
@@ -328,7 +338,6 @@ async fn run_instance<A, E, C>(
 
                     let should_exit = application.should_exit();
 
-                    theme = application.theme();
                     user_interface = ManuallyDrop::new(build_user_interface(
                         &mut application,
                         cache,
@@ -345,7 +354,10 @@ async fn run_instance<A, E, C>(
                 debug.draw_started();
                 let new_mouse_interaction = user_interface.draw(
                     &mut renderer,
-                    &theme,
+                    state.theme(),
+                    &renderer::Style {
+                        text_color: state.text_color(),
+                    },
                     state.cursor_position(),
                 );
                 debug.draw_finished();
@@ -396,7 +408,10 @@ async fn run_instance<A, E, C>(
                     debug.draw_started();
                     let new_mouse_interaction = user_interface.draw(
                         &mut renderer,
-                        &theme,
+                        state.theme(),
+                        &renderer::Style {
+                            text_color: state.text_color(),
+                        },
                         state.cursor_position(),
                     );
 
@@ -422,7 +437,7 @@ async fn run_instance<A, E, C>(
                     &mut renderer,
                     &mut surface,
                     state.viewport(),
-                    theme.background_color(),
+                    state.background_color(),
                     &debug.overlay(),
                 ) {
                     Ok(()) => {
@@ -531,7 +546,9 @@ pub fn update<A: Application, E: Executor>(
     messages: &mut Vec<A::Message>,
     window: &winit::window::Window,
     graphics_info: impl FnOnce() -> compositor::Information + Copy,
-) {
+) where
+    <A::Renderer as crate::Renderer>::Theme: StyleSheet,
+{
     for message in messages.drain(..) {
         debug.log_message(&message);
 
diff --git a/winit/src/application/state.rs b/winit/src/application/state.rs
index 34a9b10e..6b843919 100644
--- a/winit/src/application/state.rs
+++ b/winit/src/application/state.rs
@@ -1,13 +1,17 @@
+use crate::application::{self, StyleSheet as _};
 use crate::conversion;
-use crate::{Application, Debug, Mode, Point, Size, Viewport};
+use crate::{Application, Color, Debug, Mode, Point, Size, Viewport};
 
 use std::marker::PhantomData;
 use winit::event::{Touch, WindowEvent};
 use winit::window::Window;
 
 /// The state of a windowed [`Application`].
-#[derive(Debug, Clone)]
-pub struct State<A: Application> {
+#[allow(missing_debug_implementations)]
+pub struct State<A: Application>
+where
+    <A::Renderer as crate::Renderer>::Theme: application::StyleSheet,
+{
     title: String,
     mode: Mode,
     scale_factor: f64,
@@ -15,15 +19,22 @@ pub struct State<A: Application> {
     viewport_version: usize,
     cursor_position: winit::dpi::PhysicalPosition<f64>,
     modifiers: winit::event::ModifiersState,
+    theme: <A::Renderer as crate::Renderer>::Theme,
+    appearance: application::Appearance,
     application: PhantomData<A>,
 }
 
-impl<A: Application> State<A> {
+impl<A: Application> State<A>
+where
+    <A::Renderer as crate::Renderer>::Theme: application::StyleSheet,
+{
     /// Creates a new [`State`] for the provided [`Application`] and window.
     pub fn new(application: &A, window: &Window) -> Self {
         let title = application.title();
         let mode = application.mode();
         let scale_factor = application.scale_factor();
+        let theme = application.theme();
+        let appearance = theme.appearance(application.style());
 
         let viewport = {
             let physical_size = window.inner_size();
@@ -43,6 +54,8 @@ impl<A: Application> State<A> {
             // TODO: Encode cursor availability in the type-system
             cursor_position: winit::dpi::PhysicalPosition::new(-1.0, -1.0),
             modifiers: winit::event::ModifiersState::default(),
+            theme,
+            appearance,
             application: PhantomData,
         }
     }
@@ -87,6 +100,21 @@ impl<A: Application> State<A> {
         self.modifiers
     }
 
+    /// Returns the current theme of the [`State`].
+    pub fn theme(&self) -> &<A::Renderer as crate::Renderer>::Theme {
+        &self.theme
+    }
+
+    /// Returns the current background [`Color`] of the [`State`].
+    pub fn background_color(&self) -> Color {
+        self.appearance.background_color
+    }
+
+    /// Returns the current text [`Color`] of the [`State`].
+    pub fn text_color(&self) -> Color {
+        self.appearance.text_color
+    }
+
     /// Processes the provided window event and updates the [`State`]
     /// accordingly.
     pub fn update(
@@ -192,5 +220,9 @@ impl<A: Application> State<A> {
 
             self.scale_factor = new_scale_factor;
         }
+
+        // Update theme and appearance
+        self.theme = application.theme();
+        self.appearance = self.theme.appearance(application.style());
     }
 }