Add clock example

examples/clock.rs

@@ -0,0 +1,166 @@
+use iced::{
+    Align, Application, Checkbox, Column, Command, Container, Element, Length,
+    Settings, Subscription, Text,
+};
+
+pub fn main() {
+    Clock::run(Settings::default())
+}
+
+#[derive(Debug)]
+struct Clock {
+    time: chrono::DateTime<chrono::Local>,
+    enabled: bool,
+}
+
+#[derive(Debug, Clone)]
+enum Message {
+    Ticked(chrono::DateTime<chrono::Local>),
+    Toggled(bool),
+}
+
+impl Application for Clock {
+    type Message = Message;
+
+    fn new() -> (Clock, Command<Message>) {
+        (
+            Clock {
+                time: chrono::Local::now(),
+                enabled: false,
+            },
+            Command::none(),
+        )
+    }
+
+    fn title(&self) -> String {
+        String::from("Clock - Iced")
+    }
+
+    fn update(&mut self, message: Message) -> Command<Message> {
+        match message {
+            Message::Ticked(time) => {
+                self.time = time;
+            }
+            Message::Toggled(enabled) => {
+                self.enabled = enabled;
+            }
+        };
+
+        Command::none()
+    }
+
+    fn subscriptions(&self) -> Subscription<Message> {
+        if self.enabled {
+            time::every(std::time::Duration::from_millis(500), Message::Ticked)
+        } else {
+            Subscription::none()
+        }
+    }
+
+    fn view(&mut self) -> Element<Message> {
+        let clock = Text::new(format!("{}", self.time.format("%H:%M:%S")))
+            .size(40)
+            .width(Length::Shrink);
+
+        let toggle = Checkbox::new(self.enabled, "Enabled", Message::Toggled)
+            .width(Length::Shrink);
+
+        let content = Column::new()
+            .width(Length::Shrink)
+            .align_items(Align::Center)
+            .spacing(20)
+            .push(clock)
+            .push(toggle);
+
+        Container::new(content)
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .center_x()
+            .center_y()
+            .into()
+    }
+}
+
+mod time {
+    use std::sync::{Arc, Mutex};
+
+    pub fn every<Message>(
+        duration: std::time::Duration,
+        f: impl Fn(chrono::DateTime<chrono::Local>) -> Message
+            + 'static
+            + Send
+            + Sync,
+    ) -> iced::Subscription<Message>
+    where
+        Message: Send + 'static,
+    {
+        Tick {
+            duration,
+            message: Arc::new(f),
+        }
+        .into()
+    }
+
+    struct Tick<Message> {
+        duration: std::time::Duration,
+        message: Arc<
+            dyn Fn(chrono::DateTime<chrono::Local>) -> Message + Send + Sync,
+        >,
+    }
+
+    struct TickState {
+        alive: Arc<Mutex<bool>>,
+    }
+
+    impl iced::subscription::Handle for TickState {
+        fn cancel(&mut self) {
+            match self.alive.lock() {
+                Ok(mut guard) => *guard = false,
+                _ => {}
+            }
+        }
+    }
+
+    impl<Message> iced::subscription::Definition for Tick<Message>
+    where
+        Message: 'static,
+    {
+        type Message = Message;
+
+        fn id(&self) -> u64 {
+            0
+        }
+
+        fn stream(
+            &self,
+        ) -> (
+            futures::stream::BoxStream<'static, Message>,
+            Box<dyn iced::subscription::Handle>,
+        ) {
+            use futures::StreamExt;
+
+            let duration = self.duration.clone();
+            let function = self.message.clone();
+            let alive = Arc::new(Mutex::new(true));
+
+            let state = TickState {
+                alive: alive.clone(),
+            };
+
+            let stream = futures::stream::poll_fn(move |_| {
+                std::thread::sleep(duration);
+
+                if !*alive.lock().unwrap() {
+                    return std::task::Poll::Ready(None);
+                }
+
+                let now = chrono::Local::now();
+
+                std::task::Poll::Ready(Some(now))
+            })
+            .map(move |time| function(time));
+
+            (stream.boxed(), Box::new(state))
+        }
+    }
+}