Move winit logic from iced to iced_winit

- Added new `renderer::Windowed` trait. This shoud allow users to easily
  try different renderers by simply changing one line.
- Renamed `UserInterface` traits to `Application`, as the `run` method
  takes total control of the current thread.
- Moved `MouseCursor` back to `iced_native`. The new
  `renderer::Windowed` trait returns one on `draw`.
- Split `iced_native` renderer in multiple modules, for consistency.

src/lib.rs

@@ -9,123 +9,35 @@ pub type Row<'a, Message> = iced_winit::Row<'a, Message, Renderer>;
 pub type Column<'a, Message> = iced_winit::Column<'a, Message, Renderer>;
 pub type Button<'a, Message> = iced_winit::Button<'a, Message, Renderer>;
 
-pub trait UserInterface {
+pub trait Application {
     type Message;
 
     fn update(&mut self, message: Self::Message);
 
     fn view(&mut self) -> Element<Self::Message>;
 
-    fn run(mut self)
+    fn run(self)
     where
         Self: 'static + Sized,
     {
-        use winit::{
-            event::{Event, WindowEvent},
-            event_loop::{ControlFlow, EventLoop},
-            window::WindowBuilder,
-        };
-
-        let event_loop = EventLoop::new();
-
-        // TODO: Ask for window settings and configure this properly
-        let window = WindowBuilder::new()
-            .build(&event_loop)
-            .expect("Open window");
-
-        let size = window.inner_size().to_physical(window.hidpi_factor());;
-        let (width, height) = (size.width as u16, size.height as u16);
-
-        let mut renderer = Renderer::new(&window);
-        let mut target = renderer.target(width, height);
-
-        let user_interface = iced_winit::UserInterface::build(
-            document(&mut self, width, height),
-            iced_winit::Cache::default(),
-            &mut renderer,
-        );
-
-        let mut primitive = user_interface.draw(&mut renderer);
-        let mut cache = Some(user_interface.into_cache());
-        let mut events = Vec::new();
-
-        window.request_redraw();
-
-        event_loop.run(move |event, _, control_flow| match event {
-            Event::EventsCleared => {
-                // TODO: We should be able to keep a user interface alive
-                // between events once we remove state references.
-                //
-                // This will allow us to rebuild it only when a message is
-                // handled.
-                let mut user_interface = iced_winit::UserInterface::build(
-                    document(&mut self, width, height),
-                    cache.take().unwrap(),
-                    &mut renderer,
-                );
-
-                let messages = user_interface.update(events.drain(..));
-
-                if messages.is_empty() {
-                    primitive = user_interface.draw(&mut renderer);
-
-                    cache = Some(user_interface.into_cache());
-                } else {
-                    // When there are messages, we are forced to rebuild twice
-                    // for now :^)
-                    let temp_cache = user_interface.into_cache();
-
-                    for message in messages {
-                        self.update(message);
-                    }
-
-                    let user_interface = iced_winit::UserInterface::build(
-                        document(&mut self, width, height),
-                        temp_cache,
-                        &mut renderer,
-                    );
-
-                    primitive = user_interface.draw(&mut renderer);
-
-                    cache = Some(user_interface.into_cache());
-                }
-
-                window.request_redraw();
-            }
-            Event::WindowEvent {
-                event: WindowEvent::RedrawRequested,
-                ..
-            } => {
-                renderer.draw(&mut target, &primitive);
-
-                // TODO: Handle animations!
-                // Maybe we can use `ControlFlow::WaitUntil` for this.
-            }
-            Event::WindowEvent {
-                event: WindowEvent::CloseRequested,
-                ..
-            } => {
-                *control_flow = ControlFlow::Exit;
-            }
-            _ => {
-                *control_flow = ControlFlow::Wait;
-            }
-        })
+        iced_winit::Application::run(Instance(self))
     }
 }
 
-fn document<UserInterface>(
-    user_interface: &mut UserInterface,
-    width: u16,
-    height: u16,
-) -> Element<UserInterface::Message>
+struct Instance<A: Application>(A);
+
+impl<A> iced_winit::Application for Instance<A>
 where
-    UserInterface: self::UserInterface,
-    UserInterface::Message: 'static,
+    A: Application,
 {
-    Column::new()
-        .width(Length::Units(width))
-        .height(Length::Units(height))
-        .push(user_interface.view())
-        .into()
+    type Renderer = Renderer;
+    type Message = A::Message;
+
+    fn update(&mut self, message: Self::Message) {
+        self.0.update(message);
+    }
+
+    fn view(&mut self) -> Element<Self::Message> {
+        self.0.view()
+    }
 }