Add async-callback channel to Cursive

And remove it from ProgressBar

examples/progress.rs

@@ -4,7 +4,7 @@ use cursive::prelude::*;
 
 use std::thread;
 use std::time::Duration;
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
 fn main() {
@@ -16,15 +16,15 @@ fn main() {
         .content(Button::new("Start", |s| {
             // These two values will allow us to communicate.
             let value = Arc::new(AtomicUsize::new(0));
-            let cb = Arc::new(Mutex::new(None));
 
             let n_max = 1000;
 
             s.pop_layer();
             s.add_layer(Panel::new(FullView::full_width(ProgressBar::new()
                     .range(0, n_max)
-                    .with_value(value.clone())
-                    .with_callback(cb.clone()))));
+                    .with_value(value.clone()))));
+
+            let cb = s.cb_sink().clone();
 
             // Spawn a thread to process things in the background.
             thread::spawn(move || {
@@ -32,13 +32,15 @@ fn main() {
                     thread::sleep(Duration::from_millis(20));
                     value.fetch_add(1, Ordering::Relaxed);
                 }
-                *cb.lock().unwrap() = Some(Box::new(move |s| {
-                    s.pop_layer();
-                    s.add_layer(Dialog::empty()
-                        .title("Work done!")
-                        .content(TextView::new("Phew, that was some work!"))
-                        .button("Sure!", |s| s.quit()));
-                }));
+                cb.send(Box::new(move |s| {
+                        s.pop_layer();
+                        s.add_layer(Dialog::empty()
+                            .title("Work done!")
+                            .content(TextView::new("Phew, that was some \
+                                                    work!"))
+                            .button("Sure!", |s| s.quit()));
+                    }))
+                    .unwrap();
             });
 
         }))

src/lib.rs

@@ -97,6 +97,7 @@ pub use printer::Printer;
 
 use backend::{Backend, NcursesBackend};
 
+use std::sync::mpsc;
 use std::any::Any;
 use std::collections::HashMap;
 use std::path::Path;
@@ -126,6 +127,9 @@ pub struct Cursive {
     active_screen: ScreenId,
 
     running: bool,
+
+    cb_source: mpsc::Receiver<Box<Fn(&mut Cursive) + Send>>,
+    cb_sink: mpsc::Sender<Box<Fn(&mut Cursive) + Send>>,
 }
 
 new_default!(Cursive);
@@ -143,6 +147,8 @@ impl Cursive {
         let theme = theme::load_default();
         // let theme = theme::load_theme("assets/style.toml").unwrap();
 
+        let (tx, rx) = mpsc::channel();
+
         let mut res = Cursive {
             theme: theme,
             screens: Vec::new(),
@@ -150,6 +156,8 @@ impl Cursive {
             menubar: view::Menubar::new(),
             active_screen: 0,
             running: true,
+            cb_source: rx,
+            cb_sink: tx,
         };
 
         res.screens.push(StackView::new());
@@ -157,6 +165,17 @@ impl Cursive {
         res
     }
 
+    /// Returns a sink for asynchronous callbacks.
+    ///
+    /// Returns the sender part of a channel, that allows to send
+    /// callbacks to `self` from other threads.
+    ///
+    /// Callbacks will be executed in the order
+    /// of arrival on the next event cycle.
+    pub fn cb_sink(&self) -> &mpsc::Sender<Box<Fn(&mut Cursive) + Send>> {
+        &self.cb_sink
+    }
+
     /// Selects the menubar
     pub fn select_menubar(&mut self) {
         self.menubar.take_focus(direction::Direction::none());
@@ -454,6 +473,10 @@ impl Cursive {
 
         // And the big event loop begins!
         while self.running {
+            if let Ok(cb) = self.cb_source.try_recv() {
+                cb(self);
+            }
+
             // Do we need to redraw everytime?
             // Probably, actually.
             // TODO: Do we need to re-layout everytime?

src/view/progress_bar.rs

@@ -1,4 +1,4 @@
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 
 use std::sync::atomic::{AtomicUsize, Ordering};
 
@@ -6,7 +6,6 @@ use {Cursive, Printer};
 use vec::Vec2;
 use align::HAlign;
 use direction::Orientation;
-use event::*;
 use theme::{ColorStyle, Effect};
 use view::View;
 
@@ -18,7 +17,6 @@ pub struct ProgressBar {
     max: usize,
     value: Arc<AtomicUsize>,
     // TODO: use a Promise instead?
-    callback: Option<Arc<Mutex<CbPromise>>>,
     label_maker: Box<Fn(usize, (usize, usize)) -> String>,
 }
 
@@ -42,7 +40,6 @@ impl ProgressBar {
             min: 0,
             max: 100,
             value: Arc::new(AtomicUsize::new(0)),
-            callback: None,
             label_maker: Box::new(make_percentage),
         }
     }
@@ -53,14 +50,6 @@ impl ProgressBar {
         self
     }
 
-    /// Sets the callback to follow.
-    ///
-    /// Whenever `callback` is set, it will be called on the next event loop.
-    pub fn with_callback(mut self, callback: Arc<Mutex<CbPromise>>) -> Self {
-        self.callback = Some(callback);
-        self
-    }
-
     /// Sets the label generator.
     ///
     /// The given function will be called with `(value, (min, max))`.
@@ -132,16 +121,6 @@ impl View for ProgressBar {
         });
     }
 
-    fn on_event(&mut self, _: Event) -> EventResult {
-        if let Some(ref cb) = self.callback {
-            if let Some(cb) = cb.lock().unwrap().take() {
-                return EventResult::Consumed(Some(cb.into()));
-            }
-        }
-
-        EventResult::Ignored
-    }
-
     fn get_min_size(&mut self, size: Vec2) -> Vec2 {
         size.with_axis(Orientation::Vertical, 1)
     }