Draft Shell:request_redraw API

... and implement `TextInput` cursor blink 🎉

examples/events/Cargo.toml

@@ -6,5 +6,5 @@ edition = "2021"
 publish = false
 
 [dependencies]
-iced = { path = "../.." }
+iced = { path = "../..", features = ["debug"] }
 iced_native = { path = "../../native" }

examples/events/src/main.rs

@@ -1,11 +1,12 @@
 use iced::alignment;
 use iced::executor;
 use iced::widget::{button, checkbox, container, text, Column};
+use iced::window;
 use iced::{
     Alignment, Application, Command, Element, Length, Settings, Subscription,
     Theme,
 };
-use iced_native::{window, Event};
+use iced_native::Event;
 
 pub fn main() -> iced::Result {
     Events::run(Settings {
@@ -18,7 +19,6 @@ pub fn main() -> iced::Result {
 struct Events {
     last: Vec<iced_native::Event>,
     enabled: bool,
-    should_exit: bool,
 }
 
 #[derive(Debug, Clone)]
@@ -50,31 +50,29 @@ impl Application for Events {
                 if self.last.len() > 5 {
                     let _ = self.last.remove(0);
                 }
+
+                Command::none()
             }
             Message::EventOccurred(event) => {
                 if let Event::Window(window::Event::CloseRequested) = event {
-                    self.should_exit = true;
+                    window::close()
+                } else {
+                    Command::none()
                 }
             }
             Message::Toggled(enabled) => {
                 self.enabled = enabled;
-            }
-            Message::Exit => {
-                self.should_exit = true;
-            }
-        };
 
-        Command::none()
+                Command::none()
+            }
+            Message::Exit => window::close(),
+        }
     }
 
     fn subscription(&self) -> Subscription<Message> {
         iced_native::subscription::events().map(Message::EventOccurred)
     }
 
-    fn should_exit(&self) -> bool {
-        self.should_exit
-    }
-
     fn view(&self) -> Element<Message> {
         let events = Column::with_children(
             self.last

examples/exit/src/main.rs

@@ -1,5 +1,7 @@
+use iced::executor;
 use iced::widget::{button, column, container};
-use iced::{Alignment, Element, Length, Sandbox, Settings};
+use iced::window;
+use iced::{Alignment, Application, Command, Element, Length, Settings, Theme};
 
 pub fn main() -> iced::Result {
     Exit::run(Settings::default())
@@ -8,7 +10,6 @@ pub fn main() -> iced::Result {
 #[derive(Default)]
 struct Exit {
     show_confirm: bool,
-    exit: bool,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -17,28 +18,27 @@ enum Message {
     Exit,
 }
 
-impl Sandbox for Exit {
+impl Application for Exit {
+    type Executor = executor::Default;
     type Message = Message;
+    type Theme = Theme;
+    type Flags = ();
 
-    fn new() -> Self {
+    fn new(_flags: ()) -> (Self, Command<Message>) {
-        Self::default()
+        (Self::default(), Command::none())
     }
 
     fn title(&self) -> String {
         String::from("Exit - Iced")
     }
 
-    fn should_exit(&self) -> bool {
+    fn update(&mut self, message: Message) -> Command<Message> {
-        self.exit
-    }
-
-    fn update(&mut self, message: Message) {
         match message {
-            Message::Confirm => {
+            Message::Confirm => window::close(),
-                self.exit = true;
-            }
             Message::Exit => {
                 self.show_confirm = true;
+
+                Command::none()
             }
         }
     }

native/src/renderer.rs

@@ -36,11 +36,11 @@ pub trait Renderer: Sized {
         f: impl FnOnce(&mut Self),
     );
 
-    /// Clears all of the recorded primitives in the [`Renderer`].
-    fn clear(&mut self);
-
     /// Fills a [`Quad`] with the provided [`Background`].
     fn fill_quad(&mut self, quad: Quad, background: impl Into<Background>);
+
+    /// Clears all of the recorded primitives in the [`Renderer`].
+    fn clear(&mut self);
 }
 
 /// A polygon with four sides.

native/src/shell.rs

@@ -1,3 +1,5 @@
+use std::time::Instant;
+
 /// A connection to the state of a shell.
 ///
 /// A [`Widget`] can leverage a [`Shell`] to trigger changes in an application,
@@ -7,6 +9,7 @@
 #[derive(Debug)]
 pub struct Shell<'a, Message> {
     messages: &'a mut Vec<Message>,
+    redraw_requested_at: Option<Instant>,
     is_layout_invalid: bool,
     are_widgets_invalid: bool,
 }
@@ -16,11 +19,47 @@ impl<'a, Message> Shell<'a, Message> {
     pub fn new(messages: &'a mut Vec<Message>) -> Self {
         Self {
             messages,
+            redraw_requested_at: None,
             is_layout_invalid: false,
             are_widgets_invalid: false,
         }
     }
 
+    /// Publish the given `Message` for an application to process it.
+    pub fn publish(&mut self, message: Message) {
+        self.messages.push(message);
+    }
+
+    /// Requests a new frame to be drawn at the given [`Instant`].
+    pub fn request_redraw(&mut self, at: Instant) {
+        match self.redraw_requested_at {
+            None => {
+                self.redraw_requested_at = Some(at);
+            }
+            Some(current) if at < current => {
+                self.redraw_requested_at = Some(at);
+            }
+            _ => {}
+        }
+    }
+
+    /// Returns the requested [`Instant`] a redraw should happen, if any.
+    pub fn redraw_requested_at(&self) -> Option<Instant> {
+        self.redraw_requested_at
+    }
+
+    /// Returns whether the current layout is invalid or not.
+    pub fn is_layout_invalid(&self) -> bool {
+        self.is_layout_invalid
+    }
+
+    /// Invalidates the current application layout.
+    ///
+    /// The shell will relayout the application widgets.
+    pub fn invalidate_layout(&mut self) {
+        self.is_layout_invalid = true;
+    }
+
     /// Triggers the given function if the layout is invalid, cleaning it in the
     /// process.
     pub fn revalidate_layout(&mut self, f: impl FnOnce()) {
@@ -31,21 +70,10 @@ impl<'a, Message> Shell<'a, Message> {
         }
     }
 
-    /// Returns whether the current layout is invalid or not.
+    /// Returns whether the widgets of the current application have been
-    pub fn is_layout_invalid(&self) -> bool {
+    /// invalidated.
-        self.is_layout_invalid
+    pub fn are_widgets_invalid(&self) -> bool {
-    }
+        self.are_widgets_invalid
-
-    /// Publish the given `Message` for an application to process it.
-    pub fn publish(&mut self, message: Message) {
-        self.messages.push(message);
-    }
-
-    /// Invalidates the current application layout.
-    ///
-    /// The shell will relayout the application widgets.
-    pub fn invalidate_layout(&mut self) {
-        self.is_layout_invalid = true;
     }
 
     /// Invalidates the current application widgets.
@@ -62,16 +90,14 @@ impl<'a, Message> Shell<'a, Message> {
     pub fn merge<B>(&mut self, other: Shell<'_, B>, f: impl Fn(B) -> Message) {
         self.messages.extend(other.messages.drain(..).map(f));
 
+        if let Some(at) = other.redraw_requested_at {
+            self.request_redraw(at);
+        }
+
         self.is_layout_invalid =
             self.is_layout_invalid || other.is_layout_invalid;
 
         self.are_widgets_invalid =
             self.are_widgets_invalid || other.are_widgets_invalid;
     }
-
-    /// Returns whether the widgets of the current application have been
-    /// invalidated.
-    pub fn are_widgets_invalid(&self) -> bool {
-        self.are_widgets_invalid
-    }
 }

native/src/subscription.rs

@@ -1,5 +1,6 @@
 //! Listen to external events in your application.
 use crate::event::{self, Event};
+use crate::window;
 use crate::Hasher;
 
 use iced_futures::futures::{self, Future, Stream};
@@ -33,7 +34,7 @@ pub type Tracker =
 
 pub use iced_futures::subscription::Recipe;
 
-/// Returns a [`Subscription`] to all the runtime events.
+/// Returns a [`Subscription`] to all the ignored runtime events.
 ///
 /// This subscription will notify your application of any [`Event`] that was
 /// not captured by any widget.
@@ -65,7 +66,10 @@ where
             use futures::stream::StreamExt;
 
             events.filter_map(move |(event, status)| {
-                future::ready(f(event, status))
+                future::ready(match event {
+                    Event::Window(window::Event::RedrawRequested(_)) => None,
+                    _ => f(event, status),
+                })
             })
         },
     })

native/src/user_interface.rs

@@ -7,6 +7,8 @@ use crate::renderer;
 use crate::widget;
 use crate::{Clipboard, Element, Layout, Point, Rectangle, Shell, Size};
 
+use std::time::Instant;
+
 /// A set of interactive graphical elements with a specific [`Layout`].
 ///
 /// It can be updated and drawn.
@@ -188,7 +190,9 @@ where
     ) -> (State, Vec<event::Status>) {
         use std::mem::ManuallyDrop;
 
-        let mut state = State::Updated;
+        let mut outdated = false;
+        let mut redraw_requested_at = None;
+
         let mut manual_overlay =
             ManuallyDrop::new(self.root.as_widget_mut().overlay(
                 &mut self.state,
@@ -217,6 +221,16 @@ where
 
                 event_statuses.push(event_status);
 
+                match (redraw_requested_at, shell.redraw_requested_at()) {
+                    (None, Some(at)) => {
+                        redraw_requested_at = Some(at);
+                    }
+                    (Some(current), Some(new)) if new < current => {
+                        redraw_requested_at = Some(new);
+                    }
+                    _ => {}
+                }
+
                 if shell.is_layout_invalid() {
                     let _ = ManuallyDrop::into_inner(manual_overlay);
 
@@ -244,7 +258,7 @@ where
                 }
 
                 if shell.are_widgets_invalid() {
-                    state = State::Outdated;
+                    outdated = true;
                 }
             }
 
@@ -289,6 +303,16 @@ where
                     self.overlay = None;
                 }
 
+                match (redraw_requested_at, shell.redraw_requested_at()) {
+                    (None, Some(at)) => {
+                        redraw_requested_at = Some(at);
+                    }
+                    (Some(current), Some(new)) if new < current => {
+                        redraw_requested_at = Some(new);
+                    }
+                    _ => {}
+                }
+
                 shell.revalidate_layout(|| {
                     self.base = renderer.layout(
                         &self.root,
@@ -299,14 +323,23 @@ where
                 });
 
                 if shell.are_widgets_invalid() {
-                    state = State::Outdated;
+                    outdated = true;
                 }
 
                 event_status.merge(overlay_status)
             })
             .collect();
 
-        (state, event_statuses)
+        (
+            if outdated {
+                State::Outdated
+            } else {
+                State::Updated {
+                    redraw_requested_at,
+                }
+            },
+            event_statuses,
+        )
     }
 
     /// Draws the [`UserInterface`] with the provided [`Renderer`].
@@ -559,5 +592,8 @@ pub enum State {
 
     /// The [`UserInterface`] is up-to-date and can be reused without
     /// rebuilding.
-    Updated,
+    Updated {
+        /// The [`Instant`] when a redraw should be performed.
+        redraw_requested_at: Option<Instant>,
+    },
 }

native/src/widget/text_input.rs

@@ -22,11 +22,14 @@ use crate::touch;
 use crate::widget;
 use crate::widget::operation::{self, Operation};
 use crate::widget::tree::{self, Tree};
+use crate::window;
 use crate::{
     Clipboard, Color, Command, Element, Layout, Length, Padding, Point,
     Rectangle, Shell, Size, Vector, Widget,
 };
 
+use std::time::{Duration, Instant};
+
 pub use iced_style::text_input::{Appearance, StyleSheet};
 
 /// A field that can be filled with text.
@@ -425,7 +428,16 @@ where
             let state = state();
             let is_clicked = layout.bounds().contains(cursor_position);
 
-            state.is_focused = is_clicked;
+            state.is_focused = if is_clicked {
+                let now = Instant::now();
+
+                Some(Focus {
+                    at: now,
+                    last_draw: now,
+                })
+            } else {
+                None
+            };
 
             if is_clicked {
                 let text_layout = layout.children().next().unwrap();
@@ -541,26 +553,30 @@ where
         Event::Keyboard(keyboard::Event::CharacterReceived(c)) => {
             let state = state();
 
-            if state.is_focused
+            if let Some(focus) = &mut state.is_focused {
-                && state.is_pasting.is_none()
+                if state.is_pasting.is_none()
-                && !state.keyboard_modifiers.command()
+                    && !state.keyboard_modifiers.command()
-                && !c.is_control()
+                    && !c.is_control()
-            {
+                {
-                let mut editor = Editor::new(value, &mut state.cursor);
+                    let mut editor = Editor::new(value, &mut state.cursor);
 
-                editor.insert(c);
+                    editor.insert(c);
 
-                let message = (on_change)(editor.contents());
+                    let message = (on_change)(editor.contents());
-                shell.publish(message);
+                    shell.publish(message);
 
-                return event::Status::Captured;
+                    focus.at = Instant::now();
+
+                    return event::Status::Captured;
+                }
             }
         }
         Event::Keyboard(keyboard::Event::KeyPressed { key_code, .. }) => {
             let state = state();
 
-            if state.is_focused {
+            if let Some(focus) = &mut state.is_focused {
                 let modifiers = state.keyboard_modifiers;
+                focus.at = Instant::now();
 
                 match key_code {
                     keyboard::KeyCode::Enter
@@ -721,7 +737,7 @@ where
                         state.cursor.select_all(value);
                     }
                     keyboard::KeyCode::Escape => {
-                        state.is_focused = false;
+                        state.is_focused = None;
                         state.is_dragging = false;
                         state.is_pasting = None;
 
@@ -742,7 +758,7 @@ where
         Event::Keyboard(keyboard::Event::KeyReleased { key_code, .. }) => {
             let state = state();
 
-            if state.is_focused {
+            if state.is_focused.is_some() {
                 match key_code {
                     keyboard::KeyCode::V => {
                         state.is_pasting = None;
@@ -765,6 +781,21 @@ where
 
             state.keyboard_modifiers = modifiers;
         }
+        Event::Window(window::Event::RedrawRequested(now)) => {
+            let state = state();
+
+            if let Some(focus) = &mut state.is_focused {
+                focus.last_draw = now;
+
+                let millis_until_redraw = CURSOR_BLINK_INTERVAL_MILLIS
+                    - (now - focus.at).as_millis()
+                        % CURSOR_BLINK_INTERVAL_MILLIS;
+
+                shell.request_redraw(
+                    now + Duration::from_millis(millis_until_redraw as u64),
+                );
+            }
+        }
         _ => {}
     }
 
@@ -820,7 +851,7 @@ pub fn draw<Renderer>(
     let text = value.to_string();
     let size = size.unwrap_or_else(|| renderer.default_size());
 
-    let (cursor, offset) = if state.is_focused() {
+    let (cursor, offset) = if let Some(focus) = &state.is_focused {
         match state.cursor.state(value) {
             cursor::State::Index(position) => {
                 let (text_value_width, offset) =
@@ -833,7 +864,13 @@ pub fn draw<Renderer>(
                         font.clone(),
                     );
 
-                (
+                let is_cursor_visible = ((focus.last_draw - focus.at)
+                    .as_millis()
+                    / CURSOR_BLINK_INTERVAL_MILLIS)
+                    % 2
+                    == 0;
+
+                let cursor = if is_cursor_visible {
                     Some((
                         renderer::Quad {
                             bounds: Rectangle {
@@ -847,9 +884,12 @@ pub fn draw<Renderer>(
                             border_color: Color::TRANSPARENT,
                         },
                         theme.value_color(style),
-                    )),
+                    ))
-                    offset,
+                } else {
-                )
+                    None
+                };
+
+                (cursor, offset)
             }
             cursor::State::Selection { start, end } => {
                 let left = start.min(end);
@@ -958,7 +998,7 @@ pub fn mouse_interaction(
 /// The state of a [`TextInput`].
 #[derive(Debug, Default, Clone)]
 pub struct State {
-    is_focused: bool,
+    is_focused: Option<Focus>,
     is_dragging: bool,
     is_pasting: Option<Value>,
     last_click: Option<mouse::Click>,
@@ -967,6 +1007,12 @@ pub struct State {
     // TODO: Add stateful horizontal scrolling offset
 }
 
+#[derive(Debug, Clone, Copy)]
+struct Focus {
+    at: Instant,
+    last_draw: Instant,
+}
+
 impl State {
     /// Creates a new [`State`], representing an unfocused [`TextInput`].
     pub fn new() -> Self {
@@ -976,7 +1022,7 @@ impl State {
     /// Creates a new [`State`], representing a focused [`TextInput`].
     pub fn focused() -> Self {
         Self {
-            is_focused: true,
+            is_focused: None,
             is_dragging: false,
             is_pasting: None,
             last_click: None,
@@ -987,7 +1033,7 @@ impl State {
 
     /// Returns whether the [`TextInput`] is currently focused or not.
     pub fn is_focused(&self) -> bool {
-        self.is_focused
+        self.is_focused.is_some()
     }
 
     /// Returns the [`Cursor`] of the [`TextInput`].
@@ -997,13 +1043,19 @@ impl State {
 
     /// Focuses the [`TextInput`].
     pub fn focus(&mut self) {
-        self.is_focused = true;
+        let now = Instant::now();
+
+        self.is_focused = Some(Focus {
+            at: now,
+            last_draw: now,
+        });
+
         self.move_cursor_to_end();
     }
 
     /// Unfocuses the [`TextInput`].
     pub fn unfocus(&mut self) {
-        self.is_focused = false;
+        self.is_focused = None;
     }
 
     /// Moves the [`Cursor`] of the [`TextInput`] to the front of the input text.
@@ -1156,3 +1208,5 @@ where
         )
         .map(text::Hit::cursor)
 }
+
+const CURSOR_BLINK_INTERVAL_MILLIS: u128 = 500;

native/src/window/event.rs

@@ -1,4 +1,5 @@
 use std::path::PathBuf;
+use std::time::Instant;
 
 /// A window-related event.
 #[derive(PartialEq, Eq, Clone, Debug)]
@@ -19,6 +20,11 @@ pub enum Event {
         height: u32,
     },
 
+    /// A window redraw was requested.
+    ///
+    /// The [`Instant`] contains the current time.
+    RedrawRequested(Instant),
+
     /// The user has requested for the window to close.
     ///
     /// Usually, you will want to terminate the execution whenever this event

src/application.rs

@@ -180,13 +180,6 @@ pub trait Application: Sized {
         1.0
     }
 
-    /// Returns whether the [`Application`] should be terminated.
-    ///
-    /// By default, it returns `false`.
-    fn should_exit(&self) -> bool {
-        false
-    }
-
     /// Runs the [`Application`].
     ///
     /// On native platforms, this method will take control of the current thread

src/sandbox.rs

@@ -140,13 +140,6 @@ pub trait Sandbox {
         1.0
     }
 
-    /// Returns whether the [`Sandbox`] should be terminated.
-    ///
-    /// By default, it returns `false`.
-    fn should_exit(&self) -> bool {
-        false
-    }
-
     /// Runs the [`Sandbox`].
     ///
     /// On native platforms, this method will take control of the current thread
@@ -203,8 +196,4 @@ where
     fn scale_factor(&self) -> f64 {
         T::scale_factor(self)
     }
-
-    fn should_exit(&self) -> bool {
-        T::should_exit(self)
-    }
 }

winit/src/application.rs

@@ -11,7 +11,7 @@ use crate::mouse;
 use crate::renderer;
 use crate::widget::operation;
 use crate::{
-    Command, Debug, Error, Executor, Proxy, Runtime, Settings, Size,
+    Command, Debug, Error, Event, Executor, Proxy, Runtime, Settings, Size,
     Subscription,
 };
 
@@ -25,6 +25,7 @@ use iced_native::user_interface::{self, UserInterface};
 pub use iced_native::application::{Appearance, StyleSheet};
 
 use std::mem::ManuallyDrop;
+use std::time::Instant;
 
 #[cfg(feature = "trace")]
 pub use profiler::Profiler;
@@ -186,7 +187,8 @@ where
 
     let (compositor, renderer) = C::new(compositor_settings, Some(&window))?;
 
-    let (mut sender, receiver) = mpsc::unbounded();
+    let (mut event_sender, event_receiver) = mpsc::unbounded();
+    let (control_sender, mut control_receiver) = mpsc::unbounded();
 
     let mut instance = Box::pin({
         let run_instance = run_instance::<A, E, C>(
@@ -196,7 +198,8 @@ where
             runtime,
             proxy,
             debug,
-            receiver,
+            event_receiver,
+            control_sender,
             init_command,
             window,
             settings.exit_on_close_request,
@@ -234,13 +237,19 @@ where
         };
 
         if let Some(event) = event {
-            sender.start_send(event).expect("Send event");
+            event_sender.start_send(event).expect("Send event");
 
             let poll = instance.as_mut().poll(&mut context);
 
-            *control_flow = match poll {
+            match poll {
-                task::Poll::Pending => ControlFlow::Wait,
+                task::Poll::Pending => {
-                task::Poll::Ready(_) => ControlFlow::Exit,
+                    if let Ok(Some(flow)) = control_receiver.try_next() {
+                        *control_flow = flow;
+                    }
+                }
+                task::Poll::Ready(_) => {
+                    *control_flow = ControlFlow::Exit;
+                }
             };
         }
     })
@@ -253,7 +262,10 @@ async fn run_instance<A, E, C>(
     mut runtime: Runtime<E, Proxy<A::Message>, A::Message>,
     mut proxy: winit::event_loop::EventLoopProxy<A::Message>,
     mut debug: Debug,
-    mut receiver: mpsc::UnboundedReceiver<winit::event::Event<'_, A::Message>>,
+    mut event_receiver: mpsc::UnboundedReceiver<
+        winit::event::Event<'_, A::Message>,
+    >,
+    mut control_sender: mpsc::UnboundedSender<winit::event_loop::ControlFlow>,
     init_command: Command<A::Message>,
     window: winit::window::Window,
     exit_on_close_request: bool,
@@ -265,6 +277,7 @@ async fn run_instance<A, E, C>(
 {
     use iced_futures::futures::stream::StreamExt;
     use winit::event;
+    use winit::event_loop::ControlFlow;
 
     let mut clipboard = Clipboard::connect(&window);
     let mut cache = user_interface::Cache::default();
@@ -309,13 +322,21 @@ async fn run_instance<A, E, C>(
     let mut mouse_interaction = mouse::Interaction::default();
     let mut events = Vec::new();
     let mut messages = Vec::new();
+    let mut redraw_pending = false;
 
     debug.startup_finished();
 
-    while let Some(event) = receiver.next().await {
+    while let Some(event) = event_receiver.next().await {
         match event {
+            event::Event::NewEvents(start_cause) => {
+                redraw_pending = matches!(
+                    start_cause,
+                    event::StartCause::Init
+                        | event::StartCause::ResumeTimeReached { .. }
+                );
+            }
             event::Event::MainEventsCleared => {
-                if events.is_empty() && messages.is_empty() {
+                if !redraw_pending && events.is_empty() && messages.is_empty() {
                     continue;
                 }
 
@@ -338,7 +359,7 @@ async fn run_instance<A, E, C>(
                 if !messages.is_empty()
                     || matches!(
                         interface_state,
-                        user_interface::State::Outdated,
+                        user_interface::State::Outdated
                     )
                 {
                     let mut cache =
@@ -376,6 +397,24 @@ async fn run_instance<A, E, C>(
                     }
                 }
 
+                // TODO: Avoid redrawing all the time by forcing widgets to
+                // request redraws on state changes
+                //
+                // Then, we can use the `interface_state` here to decide whether
+                // if a redraw is needed right away, or simply wait until a
+                // specific time.
+                let redraw_event = Event::Window(
+                    crate::window::Event::RedrawRequested(Instant::now()),
+                );
+
+                let (interface_state, _) = user_interface.update(
+                    &[redraw_event.clone()],
+                    state.cursor_position(),
+                    &mut renderer,
+                    &mut clipboard,
+                    &mut messages,
+                );
+
                 debug.draw_started();
                 let new_mouse_interaction = user_interface.draw(
                     &mut renderer,
@@ -396,6 +435,17 @@ async fn run_instance<A, E, C>(
                 }
 
                 window.request_redraw();
+                runtime
+                    .broadcast((redraw_event, crate::event::Status::Ignored));
+
+                let _ = control_sender.start_send(match interface_state {
+                    user_interface::State::Updated {
+                        redraw_requested_at: Some(at),
+                    } => ControlFlow::WaitUntil(at),
+                    _ => ControlFlow::Wait,
+                });
+
+                redraw_pending = false;
             }
             event::Event::PlatformSpecific(event::PlatformSpecific::MacOS(
                 event::MacOS::ReceivedUrl(url),