Merge pull request #2312 from iced-rs/theming-reloaded

Theming reloaded

6 files changed, 286 insertions, 275 deletions

diff --git a/src/application.rs b/src/application.rs
index 87c2607a..be0fa0de 100644
--- a/src/application.rs
+++ b/src/application.rs
@@ -1,7 +1,9 @@
 //! Build interactive cross-platform applications.
 use crate::{Command, Element, Executor, Settings, Subscription};
 
-pub use crate::style::application::{Appearance, StyleSheet};
+use crate::shell::application;
+
+pub use application::{default, Appearance, DefaultStyle};
 
 /// An interactive cross-platform application.
 ///
@@ -91,7 +93,10 @@ pub use crate::style::application::{Appearance, StyleSheet};
 ///     }
 /// }
 /// ```
-pub trait Application: Sized {
+pub trait Application: Sized
+where
+    Self::Theme: DefaultStyle,
+{
     /// The [`Executor`] that will run commands and subscriptions.
     ///
     /// The [default executor] can be a good starting point!
@@ -104,7 +109,7 @@ pub trait Application: Sized {
     type Message: std::fmt::Debug + Send;
 
     /// The theme of your [`Application`].
-    type Theme: Default + StyleSheet;
+    type Theme: Default;
 
     /// The data needed to initialize your [`Application`].
     type Flags;
@@ -148,11 +153,9 @@ pub trait Application: Sized {
         Self::Theme::default()
     }
 
-    /// Returns the current `Style` of the [`Theme`].
-    ///
-    /// [`Theme`]: Self::Theme
-    fn style(&self) -> <Self::Theme as StyleSheet>::Style {
-        <Self::Theme as StyleSheet>::Style::default()
+    /// Returns the current [`Appearance`] of the [`Application`].
+    fn style(&self, theme: &Self::Theme) -> Appearance {
+        theme.default_style()
     }
 
     /// Returns the event [`Subscription`] for the current state of the
@@ -228,11 +231,15 @@ pub trait Application: Sized {
     }
 }
 
-struct Instance<A: Application>(A);
+struct Instance<A>(A)
+where
+    A: Application,
+    A::Theme: DefaultStyle;
 
 impl<A> crate::runtime::Program for Instance<A>
 where
     A: Application,
+    A::Theme: DefaultStyle,
 {
     type Message = A::Message;
     type Theme = A::Theme;
@@ -247,9 +254,10 @@ where
     }
 }
 
-impl<A> crate::shell::Application for Instance<A>
+impl<A> application::Application for Instance<A>
 where
     A: Application,
+    A::Theme: DefaultStyle,
 {
     type Flags = A::Flags;
 
@@ -267,8 +275,8 @@ where
         self.0.theme()
     }
 
-    fn style(&self) -> <A::Theme as StyleSheet>::Style {
-        self.0.style()
+    fn style(&self, theme: &A::Theme) -> Appearance {
+        self.0.style(theme)
     }
 
     fn subscription(&self) -> Subscription<Self::Message> {
diff --git a/src/lib.rs b/src/lib.rs
index 236c64d3..c596f2a6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -162,7 +162,6 @@
 #![cfg_attr(docsrs, feature(doc_cfg))]
 use iced_widget::graphics;
 use iced_widget::renderer;
-use iced_widget::style;
 use iced_winit as shell;
 use iced_winit::core;
 use iced_winit::runtime;
@@ -186,15 +185,14 @@ pub mod advanced;
 #[cfg(feature = "multi-window")]
 pub mod multi_window;
 
-pub use style::theme;
-
 pub use crate::core::alignment;
 pub use crate::core::border;
 pub use crate::core::color;
 pub use crate::core::gradient;
+pub use crate::core::theme;
 pub use crate::core::{
     Alignment, Background, Border, Color, ContentFit, Degrees, Gradient,
-    Length, Padding, Pixels, Point, Radians, Rectangle, Shadow, Size,
+    Length, Padding, Pixels, Point, Radians, Rectangle, Shadow, Size, Theme,
     Transformation, Vector,
 };
 
@@ -314,7 +312,6 @@ pub use renderer::Renderer;
 pub use sandbox::Sandbox;
 pub use settings::Settings;
 pub use subscription::Subscription;
-pub use theme::Theme;
 
 /// A generic widget.
 ///
diff --git a/src/multi_window.rs b/src/multi_window.rs
index 5b7a00b4..c4063563 100644
--- a/src/multi_window.rs
+++ b/src/multi_window.rs
@@ -1,4 +1,256 @@
 //! Leverage multi-window support in your application.
-mod application;
+use crate::window;
+use crate::{Command, Element, Executor, Settings, Subscription};
 
-pub use application::Application;
+pub use crate::application::{Appearance, DefaultStyle};
+
+/// An interactive cross-platform multi-window application.
+///
+/// This trait is the main entrypoint of Iced. Once implemented, you can run
+/// your GUI application by simply calling [`run`](#method.run).
+///
+/// - On native platforms, it will run in its own windows.
+/// - On the web, it will take control of the `<title>` and the `<body>` of the
+///   document and display only the contents of the `window::Id::MAIN` window.
+///
+/// An [`Application`] can execute asynchronous actions by returning a
+/// [`Command`] in some of its methods. If you do not intend to perform any
+/// background work in your program, the [`Sandbox`] trait offers a simplified
+/// interface.
+///
+/// When using an [`Application`] with the `debug` feature enabled, a debug view
+/// can be toggled by pressing `F12`.
+///
+/// # Examples
+/// See the `examples/multi-window` example to see this multi-window `Application` trait in action.
+///
+/// ## A simple "Hello, world!"
+///
+/// If you just want to get started, here is a simple [`Application`] that
+/// says "Hello, world!":
+///
+/// ```no_run
+/// use iced::{executor, window};
+/// use iced::{Command, Element, Settings, Theme};
+/// use iced::multi_window::{self, Application};
+///
+/// pub fn main() -> iced::Result {
+///     Hello::run(Settings::default())
+/// }
+///
+/// struct Hello;
+///
+/// impl multi_window::Application for Hello {
+///     type Executor = executor::Default;
+///     type Flags = ();
+///     type Message = ();
+///     type Theme = Theme;
+///
+///     fn new(_flags: ()) -> (Hello, Command<Self::Message>) {
+///         (Hello, Command::none())
+///     }
+///
+///     fn title(&self, _window: window::Id) -> String {
+///         String::from("A cool application")
+///     }
+///
+///     fn update(&mut self, _message: Self::Message) -> Command<Self::Message> {
+///         Command::none()
+///     }
+///
+///     fn view(&self, _window: window::Id) -> Element<Self::Message> {
+///         "Hello, world!".into()
+///     }
+/// }
+/// ```
+///
+/// [`Sandbox`]: crate::Sandbox
+pub trait Application: Sized
+where
+    Self::Theme: DefaultStyle,
+{
+    /// The [`Executor`] that will run commands and subscriptions.
+    ///
+    /// The [default executor] can be a good starting point!
+    ///
+    /// [`Executor`]: Self::Executor
+    /// [default executor]: crate::executor::Default
+    type Executor: Executor;
+
+    /// The type of __messages__ your [`Application`] will produce.
+    type Message: std::fmt::Debug + Send;
+
+    /// The theme of your [`Application`].
+    type Theme: Default;
+
+    /// The data needed to initialize your [`Application`].
+    type Flags;
+
+    /// Initializes the [`Application`] with the flags provided to
+    /// [`run`] as part of the [`Settings`].
+    ///
+    /// Here is where you should return the initial state of your app.
+    ///
+    /// Additionally, you can return a [`Command`] if you need to perform some
+    /// async action in the background on startup. This is useful if you want to
+    /// load state from a file, perform an initial HTTP request, etc.
+    ///
+    /// [`run`]: Self::run
+    fn new(flags: Self::Flags) -> (Self, Command<Self::Message>);
+
+    /// Returns the current title of the `window` of the [`Application`].
+    ///
+    /// This title can be dynamic! The runtime will automatically update the
+    /// title of your window when necessary.
+    fn title(&self, window: window::Id) -> String;
+
+    /// Handles a __message__ and updates the state of the [`Application`].
+    ///
+    /// This is where you define your __update logic__. All the __messages__,
+    /// produced by either user interactions or commands, will be handled by
+    /// this method.
+    ///
+    /// Any [`Command`] returned will be executed immediately in the background.
+    fn update(&mut self, message: Self::Message) -> Command<Self::Message>;
+
+    /// Returns the widgets to display in the `window` of the [`Application`].
+    ///
+    /// These widgets can produce __messages__ based on user interaction.
+    fn view(
+        &self,
+        window: window::Id,
+    ) -> Element<'_, Self::Message, Self::Theme, crate::Renderer>;
+
+    /// Returns the current [`Theme`] of the `window` of the [`Application`].
+    ///
+    /// [`Theme`]: Self::Theme
+    #[allow(unused_variables)]
+    fn theme(&self, window: window::Id) -> Self::Theme {
+        Self::Theme::default()
+    }
+
+    /// Returns the current `Style` of the [`Theme`].
+    ///
+    /// [`Theme`]: Self::Theme
+    fn style(&self, theme: &Self::Theme) -> Appearance {
+        Self::Theme::default_style(theme)
+    }
+
+    /// Returns the event [`Subscription`] for the current state of the
+    /// application.
+    ///
+    /// A [`Subscription`] will be kept alive as long as you keep returning it,
+    /// and the __messages__ produced will be handled by
+    /// [`update`](#tymethod.update).
+    ///
+    /// By default, this method returns an empty [`Subscription`].
+    fn subscription(&self) -> Subscription<Self::Message> {
+        Subscription::none()
+    }
+
+    /// Returns the scale factor of the `window` of the [`Application`].
+    ///
+    /// It can be used to dynamically control the size of the UI at runtime
+    /// (i.e. zooming).
+    ///
+    /// For instance, a scale factor of `2.0` will make widgets twice as big,
+    /// while a scale factor of `0.5` will shrink them to half their size.
+    ///
+    /// By default, it returns `1.0`.
+    #[allow(unused_variables)]
+    fn scale_factor(&self, window: window::Id) -> f64 {
+        1.0
+    }
+
+    /// Runs the multi-window [`Application`].
+    ///
+    /// On native platforms, this method will take control of the current thread
+    /// until the [`Application`] exits.
+    ///
+    /// On the web platform, this method __will NOT return__ unless there is an
+    /// [`Error`] during startup.
+    ///
+    /// [`Error`]: crate::Error
+    fn run(settings: Settings<Self::Flags>) -> crate::Result
+    where
+        Self: 'static,
+    {
+        #[allow(clippy::needless_update)]
+        let renderer_settings = crate::renderer::Settings {
+            default_font: settings.default_font,
+            default_text_size: settings.default_text_size,
+            antialiasing: if settings.antialiasing {
+                Some(crate::graphics::Antialiasing::MSAAx4)
+            } else {
+                None
+            },
+            ..crate::renderer::Settings::default()
+        };
+
+        Ok(crate::shell::multi_window::run::<
+            Instance<Self>,
+            Self::Executor,
+            crate::renderer::Compositor,
+        >(settings.into(), renderer_settings)?)
+    }
+}
+
+struct Instance<A>(A)
+where
+    A: Application,
+    A::Theme: DefaultStyle;
+
+impl<A> crate::runtime::multi_window::Program for Instance<A>
+where
+    A: Application,
+    A::Theme: DefaultStyle,
+{
+    type Message = A::Message;
+    type Theme = A::Theme;
+    type Renderer = crate::Renderer;
+
+    fn update(&mut self, message: Self::Message) -> Command<Self::Message> {
+        self.0.update(message)
+    }
+
+    fn view(
+        &self,
+        window: window::Id,
+    ) -> Element<'_, Self::Message, Self::Theme, Self::Renderer> {
+        self.0.view(window)
+    }
+}
+
+impl<A> crate::shell::multi_window::Application for Instance<A>
+where
+    A: Application,
+    A::Theme: DefaultStyle,
+{
+    type Flags = A::Flags;
+
+    fn new(flags: Self::Flags) -> (Self, Command<A::Message>) {
+        let (app, command) = A::new(flags);
+
+        (Instance(app), command)
+    }
+
+    fn title(&self, window: window::Id) -> String {
+        self.0.title(window)
+    }
+
+    fn theme(&self, window: window::Id) -> A::Theme {
+        self.0.theme(window)
+    }
+
+    fn style(&self, theme: &Self::Theme) -> Appearance {
+        self.0.style(theme)
+    }
+
+    fn subscription(&self) -> Subscription<Self::Message> {
+        self.0.subscription()
+    }
+
+    fn scale_factor(&self, window: window::Id) -> f64 {
+        self.0.scale_factor(window)
+    }
+}
diff --git a/src/multi_window/application.rs b/src/multi_window/application.rs
deleted file mode 100644
index ac625281..00000000
--- a/src/multi_window/application.rs
+++ /dev/null
@@ -1,246 +0,0 @@
-use crate::style::application::StyleSheet;
-use crate::window;
-use crate::{Command, Element, Executor, Settings, Subscription};
-
-/// An interactive cross-platform multi-window application.
-///
-/// This trait is the main entrypoint of Iced. Once implemented, you can run
-/// your GUI application by simply calling [`run`](#method.run).
-///
-/// - On native platforms, it will run in its own windows.
-/// - On the web, it will take control of the `<title>` and the `<body>` of the
-///   document and display only the contents of the `window::Id::MAIN` window.
-///
-/// An [`Application`] can execute asynchronous actions by returning a
-/// [`Command`] in some of its methods. If you do not intend to perform any
-/// background work in your program, the [`Sandbox`] trait offers a simplified
-/// interface.
-///
-/// When using an [`Application`] with the `debug` feature enabled, a debug view
-/// can be toggled by pressing `F12`.
-///
-/// # Examples
-/// See the `examples/multi-window` example to see this multi-window `Application` trait in action.
-///
-/// ## A simple "Hello, world!"
-///
-/// If you just want to get started, here is a simple [`Application`] that
-/// says "Hello, world!":
-///
-/// ```no_run
-/// use iced::{executor, window};
-/// use iced::{Command, Element, Settings, Theme};
-/// use iced::multi_window::{self, Application};
-///
-/// pub fn main() -> iced::Result {
-///     Hello::run(Settings::default())
-/// }
-///
-/// struct Hello;
-///
-/// impl multi_window::Application for Hello {
-///     type Executor = executor::Default;
-///     type Flags = ();
-///     type Message = ();
-///     type Theme = Theme;
-///
-///     fn new(_flags: ()) -> (Hello, Command<Self::Message>) {
-///         (Hello, Command::none())
-///     }
-///
-///     fn title(&self, _window: window::Id) -> String {
-///         String::from("A cool application")
-///     }
-///
-///     fn update(&mut self, _message: Self::Message) -> Command<Self::Message> {
-///         Command::none()
-///     }
-///
-///     fn view(&self, _window: window::Id) -> Element<Self::Message> {
-///         "Hello, world!".into()
-///     }
-/// }
-/// ```
-///
-/// [`Sandbox`]: crate::Sandbox
-pub trait Application: Sized {
-    /// The [`Executor`] that will run commands and subscriptions.
-    ///
-    /// The [default executor] can be a good starting point!
-    ///
-    /// [`Executor`]: Self::Executor
-    /// [default executor]: crate::executor::Default
-    type Executor: Executor;
-
-    /// The type of __messages__ your [`Application`] will produce.
-    type Message: std::fmt::Debug + Send;
-
-    /// The theme of your [`Application`].
-    type Theme: Default + StyleSheet;
-
-    /// The data needed to initialize your [`Application`].
-    type Flags;
-
-    /// Initializes the [`Application`] with the flags provided to
-    /// [`run`] as part of the [`Settings`].
-    ///
-    /// Here is where you should return the initial state of your app.
-    ///
-    /// Additionally, you can return a [`Command`] if you need to perform some
-    /// async action in the background on startup. This is useful if you want to
-    /// load state from a file, perform an initial HTTP request, etc.
-    ///
-    /// [`run`]: Self::run
-    fn new(flags: Self::Flags) -> (Self, Command<Self::Message>);
-
-    /// Returns the current title of the `window` of the [`Application`].
-    ///
-    /// This title can be dynamic! The runtime will automatically update the
-    /// title of your window when necessary.
-    fn title(&self, window: window::Id) -> String;
-
-    /// Handles a __message__ and updates the state of the [`Application`].
-    ///
-    /// This is where you define your __update logic__. All the __messages__,
-    /// produced by either user interactions or commands, will be handled by
-    /// this method.
-    ///
-    /// Any [`Command`] returned will be executed immediately in the background.
-    fn update(&mut self, message: Self::Message) -> Command<Self::Message>;
-
-    /// Returns the widgets to display in the `window` of the [`Application`].
-    ///
-    /// These widgets can produce __messages__ based on user interaction.
-    fn view(
-        &self,
-        window: window::Id,
-    ) -> Element<'_, Self::Message, Self::Theme, crate::Renderer>;
-
-    /// Returns the current [`Theme`] of the `window` of the [`Application`].
-    ///
-    /// [`Theme`]: Self::Theme
-    #[allow(unused_variables)]
-    fn theme(&self, window: window::Id) -> Self::Theme {
-        Self::Theme::default()
-    }
-
-    /// Returns the current `Style` of the [`Theme`].
-    ///
-    /// [`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.
-    ///
-    /// A [`Subscription`] will be kept alive as long as you keep returning it,
-    /// and the __messages__ produced will be handled by
-    /// [`update`](#tymethod.update).
-    ///
-    /// By default, this method returns an empty [`Subscription`].
-    fn subscription(&self) -> Subscription<Self::Message> {
-        Subscription::none()
-    }
-
-    /// Returns the scale factor of the `window` of the [`Application`].
-    ///
-    /// It can be used to dynamically control the size of the UI at runtime
-    /// (i.e. zooming).
-    ///
-    /// For instance, a scale factor of `2.0` will make widgets twice as big,
-    /// while a scale factor of `0.5` will shrink them to half their size.
-    ///
-    /// By default, it returns `1.0`.
-    #[allow(unused_variables)]
-    fn scale_factor(&self, window: window::Id) -> f64 {
-        1.0
-    }
-
-    /// Runs the multi-window [`Application`].
-    ///
-    /// On native platforms, this method will take control of the current thread
-    /// until the [`Application`] exits.
-    ///
-    /// On the web platform, this method __will NOT return__ unless there is an
-    /// [`Error`] during startup.
-    ///
-    /// [`Error`]: crate::Error
-    fn run(settings: Settings<Self::Flags>) -> crate::Result
-    where
-        Self: 'static,
-    {
-        #[allow(clippy::needless_update)]
-        let renderer_settings = crate::renderer::Settings {
-            default_font: settings.default_font,
-            default_text_size: settings.default_text_size,
-            antialiasing: if settings.antialiasing {
-                Some(crate::graphics::Antialiasing::MSAAx4)
-            } else {
-                None
-            },
-            ..crate::renderer::Settings::default()
-        };
-
-        Ok(crate::shell::multi_window::run::<
-            Instance<Self>,
-            Self::Executor,
-            crate::renderer::Compositor,
-        >(settings.into(), renderer_settings)?)
-    }
-}
-
-struct Instance<A: Application>(A);
-
-impl<A> crate::runtime::multi_window::Program for Instance<A>
-where
-    A: Application,
-{
-    type Message = A::Message;
-    type Theme = A::Theme;
-    type Renderer = crate::Renderer;
-
-    fn update(&mut self, message: Self::Message) -> Command<Self::Message> {
-        self.0.update(message)
-    }
-
-    fn view(
-        &self,
-        window: window::Id,
-    ) -> Element<'_, Self::Message, Self::Theme, Self::Renderer> {
-        self.0.view(window)
-    }
-}
-
-impl<A> crate::shell::multi_window::Application for Instance<A>
-where
-    A: Application,
-{
-    type Flags = A::Flags;
-
-    fn new(flags: Self::Flags) -> (Self, Command<A::Message>) {
-        let (app, command) = A::new(flags);
-
-        (Instance(app), command)
-    }
-
-    fn title(&self, window: window::Id) -> String {
-        self.0.title(window)
-    }
-
-    fn theme(&self, window: window::Id) -> A::Theme {
-        self.0.theme(window)
-    }
-
-    fn style(&self) -> <A::Theme as StyleSheet>::Style {
-        self.0.style()
-    }
-
-    fn subscription(&self) -> Subscription<Self::Message> {
-        self.0.subscription()
-    }
-
-    fn scale_factor(&self, window: window::Id) -> f64 {
-        self.0.scale_factor(window)
-    }
-}
diff --git a/src/sandbox.rs b/src/sandbox.rs
index 28461929..568b673e 100644
--- a/src/sandbox.rs
+++ b/src/sandbox.rs
@@ -1,5 +1,5 @@
-use crate::theme::{self, Theme};
-use crate::{Application, Command, Element, Error, Settings, Subscription};
+use crate::application::{self, Application};
+use crate::{Command, Element, Error, Settings, Subscription, Theme};
 
 /// A sandboxed [`Application`].
 ///
@@ -120,11 +120,11 @@ pub trait Sandbox {
         Theme::default()
     }
 
-    /// Returns the current style variant of [`theme::Application`].
-    ///
-    /// By default, it returns [`theme::Application::default`].
-    fn style(&self) -> theme::Application {
-        theme::Application::default()
+    /// Returns the current [`application::Appearance`].
+    fn style(&self, theme: &Theme) -> application::Appearance {
+        use application::DefaultStyle;
+
+        theme.default_style()
     }
 
     /// Returns the scale factor of the [`Sandbox`].
@@ -185,8 +185,8 @@ where
         T::theme(self)
     }
 
-    fn style(&self) -> theme::Application {
-        T::style(self)
+    fn style(&self, theme: &Theme) -> application::Appearance {
+        T::style(self, theme)
     }
 
     fn subscription(&self) -> Subscription<T::Message> {
diff --git a/src/time.rs b/src/time.rs
index e255d751..26d31c0a 100644
--- a/src/time.rs
+++ b/src/time.rs
@@ -1,5 +1,5 @@
 //! Listen and react to time.
-pub use iced_core::time::{Duration, Instant};
+pub use crate::core::time::{Duration, Instant};
 
 #[allow(unused_imports)]
 #[cfg_attr(