Introduce opaque window::Id type

native/src/window.rs

@@ -1,10 +1,12 @@
 //! Build window-based GUI applications.
 mod action;
 mod event;
+mod id;
 mod mode;
 mod user_attention;
 
 pub use action::Action;
 pub use event::Event;
+pub use id::Id;
 pub use mode::Mode;
 pub use user_attention::UserAttention;

native/src/window/id.rs

@@ -0,0 +1,16 @@
+use std::collections::hash_map::DefaultHasher;
+use std::hash::{Hash, Hasher};
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+/// TODO(derezzedex)
+pub struct Id(u64);
+
+impl Id {
+    /// TODO(derezzedex)
+    pub fn new(id: impl Hash) -> Id {
+        let mut hasher = DefaultHasher::new();
+        id.hash(&mut hasher);
+
+        Id(hasher.finish())
+    }
+}

src/multi_window/application.rs

@@ -1,3 +1,4 @@
+use crate::window;
 use crate::{Command, Element, Executor, Settings, Subscription};
 
 pub use iced_native::application::{Appearance, StyleSheet};
@@ -45,6 +46,9 @@ pub trait Application: Sized {
     /// title of your application when necessary.
     fn title(&self) -> String;
 
+    /// TODO(derezzedex)
+    fn windows(&self) -> Vec<(window::Id, window::Settings)>;
+
     /// Handles a __message__ and updates the state of the [`Application`].
     ///
     /// This is where you define your __update logic__. All the __messages__,
@@ -160,6 +164,16 @@ where
         self.0.title()
     }
 
+    fn windows(&self) -> Vec<(window::Id, iced_winit::settings::Window)> {
+        self.0
+            .windows()
+            .into_iter()
+            .map(|(id, settings)| {
+                (id, iced_winit::settings::Window::from(settings))
+            })
+            .collect()
+    }
+
     fn update(&mut self, message: Self::Message) -> Command<Self::Message> {
         self.0.update(message)
     }

winit/src/multi_window.rs

@@ -9,6 +9,7 @@ use crate::mouse;
 use crate::renderer;
 use crate::settings;
 use crate::widget::operation;
+use crate::window;
 use crate::{
     Command, Debug, Element, Error, Executor, Proxy, Renderer, Runtime,
     Settings, Size, Subscription,
@@ -17,7 +18,6 @@ use crate::{
 use iced_futures::futures::channel::mpsc;
 use iced_futures::futures::{self, FutureExt};
 use iced_graphics::compositor;
-use iced_graphics::window;
 use iced_native::user_interface::{self, UserInterface};
 
 pub use iced_native::application::{Appearance, StyleSheet};
@@ -37,9 +37,9 @@ pub enum Event<Message> {
     /// TODO(derezzedex)
     // Create a wrapper variant of `window::Event` type instead
     // (maybe we should also allow users to listen/react to those internal messages?)
-    NewWindow(usize, settings::Window),
+    NewWindow(window::Id, settings::Window),
     /// TODO(derezzedex)
-    WindowCreated(usize, winit::window::Window),
+    WindowCreated(window::Id, winit::window::Window),
 }
 
 /// An interactive, native cross-platform application.
@@ -66,6 +66,9 @@ where
     /// The type of __messages__ your [`Program`] will produce.
     type Message: std::fmt::Debug + Send;
 
+    /// TODO(derezzedex)
+    fn windows(&self) -> Vec<(window::Id, settings::Window)>;
+
     /// Handles a __message__ and updates the state of the [`Program`].
     ///
     /// This is where you define your __update logic__. All the __messages__,
@@ -150,7 +153,7 @@ pub fn run<A, E, C>(
 where
     A: Application + 'static,
     E: Executor + 'static,
-    C: window::Compositor<Renderer = A::Renderer> + 'static,
+    C: iced_graphics::window::Compositor<Renderer = A::Renderer> + 'static,
     <A::Renderer as crate::Renderer>::Theme: StyleSheet,
 {
     use futures::task;
@@ -188,8 +191,8 @@ where
         .build(&event_loop)
         .map_err(Error::WindowCreationFailed)?;
 
-    let windows: HashMap<usize, winit::window::Window> =
+    let windows: HashMap<window::Id, winit::window::Window> =
-        HashMap::from([(0usize, window)]);
+        HashMap::from([(window::Id::new(0usize), window)]);
     let window = windows.values().next().expect("No window found");
 
     #[cfg(target_arch = "wasm32")]
@@ -287,12 +290,12 @@ async fn run_instance<A, E, C>(
         winit::event::Event<'_, Event<A::Message>>,
     >,
     init_command: Command<A::Message>,
-    mut windows: HashMap<usize, winit::window::Window>,
+    mut windows: HashMap<window::Id, winit::window::Window>,
     exit_on_close_request: bool,
 ) where
     A: Application + 'static,
     E: Executor + 'static,
-    C: window::Compositor<Renderer = A::Renderer> + 'static,
+    C: iced_graphics::window::Compositor<Renderer = A::Renderer> + 'static,
     <A::Renderer as crate::Renderer>::Theme: StyleSheet,
 {
     use iced_futures::futures::stream::StreamExt;
@@ -629,7 +632,7 @@ pub fn update<A: Application, E: Executor>(
     proxy: &mut winit::event_loop::EventLoopProxy<Event<A::Message>>,
     debug: &mut Debug,
     messages: &mut Vec<A::Message>,
-    windows: &HashMap<usize, winit::window::Window>,
+    windows: &HashMap<window::Id, winit::window::Window>,
     graphics_info: impl FnOnce() -> compositor::Information + Copy,
 ) where
     <A::Renderer as crate::Renderer>::Theme: StyleSheet,
@@ -671,7 +674,7 @@ pub fn run_command<A, E>(
     clipboard: &mut Clipboard,
     proxy: &mut winit::event_loop::EventLoopProxy<Event<A::Message>>,
     debug: &mut Debug,
-    windows: &HashMap<usize, winit::window::Window>,
+    windows: &HashMap<window::Id, winit::window::Window>,
     _graphics_info: impl FnOnce() -> compositor::Information + Copy,
 ) where
     A: Application,

winit/src/multi_window/state.rs

@@ -1,6 +1,7 @@
 use crate::application::{self, StyleSheet as _};
 use crate::conversion;
 use crate::multi_window::{Application, Event};
+use crate::window;
 use crate::{Color, Debug, Point, Size, Viewport};
 
 use std::collections::HashMap;
@@ -186,7 +187,7 @@ where
     pub fn synchronize(
         &mut self,
         application: &A,
-        windows: &HashMap<usize, Window>,
+        windows: &HashMap<window::Id, Window>,
         proxy: &EventLoopProxy<Event<A::Message>>,
     ) {
         let new_windows = application.windows();

winit/src/window.rs

@@ -2,7 +2,7 @@
 use crate::command::{self, Command};
 use iced_native::window;
 
-pub use window::{Event, Mode, UserAttention};
+pub use window::{Id, Event, Mode, UserAttention};
 
 /// Closes the current window and exits the application.
 pub fn close<Message>() -> Command<Message> {