Refactor Backend input model

Backends now have to send input to the given `chan::Sender<Event>`.
They send these events from a separate thread, allowing selection
between input and callbacks.

This currently breaks the BearLibTerminal backend, which requires all
calls to come from the UI thread.

This might not be super-safe for the ncurses backend also. We hope that
input and output are separate enough that they can run concurrently without
problem.

Cargo.toml

@@ -24,6 +24,7 @@ unicode-segmentation = "1.0"
 unicode-width = "0.1"
 xi-unicode = "0.1.0"
 libc = "0.2"
+chan = "0.1"
 
 [dependencies.maplit]
 optional = true
@@ -33,10 +34,6 @@ version = "1.0.0"
 optional = true
 version = "1.3.1"
 
-[dependencies.chan]
-optional = true
-version = "0.1.18"
-
 [dependencies.chan-signal]
 optional = true
 version = "0.3"
@@ -70,7 +67,7 @@ default = ["ncurses-backend"]
 markdown = ["pulldown-cmark"]
 ncurses-backend = ["ncurses", "maplit"]
 pancurses-backend = ["pancurses", "maplit"]
-termion-backend = ["termion", "chan", "chan-signal"]
+termion-backend = ["termion", "chan-signal"]
 
 [lib]
 name = "cursive"

examples/position.rs

@@ -23,7 +23,6 @@ fn move_top(c: &mut Cursive, x_in: isize, y_in: isize) {
 
 fn main() {
     let mut siv = Cursive::default();
-    siv.set_fps(60);
 
     // We can quit by pressing `q`
     siv.add_global_callback('q', Cursive::quit);

examples/progress.rs

@@ -27,7 +27,7 @@ fn main() {
             .content(Button::new("Start", phase_1)),
     );
 
-    // Auto-refresh is currently required for animated views
+    // Auto-refresh is required for animated views
     siv.set_fps(30);
 
     siv.run();
@@ -52,7 +52,7 @@ fn phase_1(s: &mut Cursive) {
                 fake_load(n_max, &counter);
 
                 // When we're done, send a callback through the channel
-                cb.send(Box::new(coffee_break)).unwrap();
+                cb.send(Box::new(coffee_break));
             })
             .full_width(),
     ));
@@ -110,7 +110,7 @@ fn phase_2(s: &mut Cursive) {
             }
         }
 
-        cb.send(Box::new(final_step)).unwrap();
+        cb.send(Box::new(final_step));
     });
 }
 

examples/vpv.rs

@@ -68,9 +68,7 @@ fn main() {
         }
 
         // When we're done, shut down the application
-        cb_sink
+        cb_sink.send(Box::new(|s: &mut Cursive| s.quit()));
-            .send(Box::new(|s: &mut Cursive| s.quit()))
-            .unwrap();
     });
 
     // Add a single view: progress status

src/backend/blt.rs

@@ -14,6 +14,8 @@ use event::{Event, Key, MouseButton, MouseEvent};
 use std::collections::HashSet;
 use theme::{BaseColor, Color, ColorPair, Effect};
 use vec::Vec2;
+use chan;
+use std::thread;
 
 enum ColorRole {
     Foreground,
@@ -21,31 +23,81 @@ enum ColorRole {
 }
 
 pub struct Backend {
-    mouse_position: Vec2,
-    buttons_pressed: HashSet<MouseButton>,
 }
 
-impl Backend {
+struct InputParser {
-    pub fn init() -> Box<Self> {
+    event_sink: chan::Sender<Event>,
-        terminal::open("Cursive", 80, 24);
+    buttons_pressed: HashSet<MouseButton>,
-        terminal::set(terminal::config::Window::empty().resizeable(true));
+    mouse_position: Vec2,
-        terminal::set(vec![
+}
-            terminal::config::InputFilter::Group {
-                group: terminal::config::InputFilterGroup::Keyboard,
-                both: false,
-            },
-            terminal::config::InputFilter::Group {
-                group: terminal::config::InputFilterGroup::Mouse,
-                both: true,
-            },
-        ]);
 
-        let c = Backend {
+impl InputParser {
-            mouse_position: Vec2::zero(),
+    fn new(event_sink: chan::Sender<Event>) -> Self {
+        InputParser {
+            event_sink,
             buttons_pressed: HashSet::new(),
-        };
+            mouse_position: Vec2::zero(),
+        }
+    }
 
-        Box::new(c)
+    fn parse_next(&mut self) {
+
+        // TODO: we could add backend-specific controls here.
+        // Ex: ctrl+mouse wheel cause window cellsize to change
+        let event = if let Some(ev) = terminal::wait_event() {
+            match ev {
+                BltEvent::Close => Event::Exit,
+                BltEvent::Resize { .. } => Event::WindowResize,
+                // TODO: mouse support
+                BltEvent::MouseMove { x, y } => {
+                    self.mouse_position = Vec2::new(x as usize, y as usize);
+                    // TODO: find out if a button is pressed?
+                    match self.buttons_pressed.iter().next() {
+                        None => Event::Refresh,
+                        Some(btn) => Event::Mouse {
+                            event: MouseEvent::Hold(*btn),
+                            position: self.mouse_position,
+                            offset: Vec2::zero(),
+                        },
+                    }
+                }
+                BltEvent::MouseScroll { delta } => Event::Mouse {
+                    event: if delta < 0 {
+                        MouseEvent::WheelUp
+                    } else {
+                        MouseEvent::WheelDown
+                    },
+                    position: self.mouse_position,
+                    offset: Vec2::zero(),
+                },
+                BltEvent::KeyPressed { key, ctrl, shift } => {
+                    self.blt_keycode_to_ev(key, shift, ctrl)
+                }
+                // TODO: there's no Key::Shift/Ctrl for w/e reason
+                BltEvent::ShiftPressed => Event::Refresh,
+                BltEvent::ControlPressed => Event::Refresh,
+                // TODO: what should we do here?
+                BltEvent::KeyReleased { key, .. } => {
+                    // It's probably a mouse key.
+                    blt_keycode_to_mouse_button(key)
+                        .map(|btn| {
+                            self.buttons_pressed.remove(&btn);
+                            Event::Mouse {
+                                event: MouseEvent::Release(btn),
+                                position: self.mouse_position,
+                                offset: Vec2::zero(),
+                            }
+                        })
+                    .unwrap_or(Event::Unknown(vec![]))
+                }
+                BltEvent::ShiftReleased | BltEvent::ControlReleased => {
+                    Event::Refresh
+                }
+            }
+        } else {
+            Event::Refresh
+        };
+        self.event_sink.send(event);
     }
 
     fn blt_keycode_to_ev(
@@ -171,6 +223,28 @@ impl Backend {
     }
 }
 
+impl Backend {
+    pub fn init() -> Box<backend::Backend> {
+        terminal::open("Cursive", 80, 24);
+        terminal::set(terminal::config::Window::empty().resizeable(true));
+        terminal::set(vec![
+            terminal::config::InputFilter::Group {
+                group: terminal::config::InputFilterGroup::Keyboard,
+                both: false,
+            },
+            terminal::config::InputFilter::Group {
+                group: terminal::config::InputFilterGroup::Mouse,
+                both: true,
+            },
+        ]);
+
+        let c = Backend {};
+
+        Box::new(c)
+    }
+
+}
+
 impl backend::Backend for Backend {
     fn finish(&mut self) {
         terminal::close();
@@ -246,66 +320,14 @@ impl backend::Backend for Backend {
         terminal::print_xy(pos.x as i32, pos.y as i32, text);
     }
 
-    fn set_refresh_rate(&mut self, _: u32) {
+    fn start_input_thread(&mut self, event_sink: chan::Sender<Event>) {
-        // TODO: unsupported
+        let mut parser = InputParser::new(event_sink);
-    }
 
-    fn poll_event(&mut self) -> Event {
+        thread::spawn(move || {
-        // TODO: we could add backend-specific controls here.
+            loop {
-        // Ex: ctrl+mouse wheel cause window cellsize to change
+                parser.parse_next();
-        if let Some(ev) = terminal::wait_event() {
-            match ev {
-                BltEvent::Close => Event::Exit,
-                BltEvent::Resize { .. } => Event::WindowResize,
-                // TODO: mouse support
-                BltEvent::MouseMove { x, y } => {
-                    self.mouse_position = Vec2::new(x as usize, y as usize);
-                    // TODO: find out if a button is pressed?
-                    match self.buttons_pressed.iter().next() {
-                        None => Event::Refresh,
-                        Some(btn) => Event::Mouse {
-                            event: MouseEvent::Hold(*btn),
-                            position: self.mouse_position,
-                            offset: Vec2::zero(),
-                        },
-                    }
-                }
-                BltEvent::MouseScroll { delta } => Event::Mouse {
-                    event: if delta < 0 {
-                        MouseEvent::WheelUp
-                    } else {
-                        MouseEvent::WheelDown
-                    },
-                    position: self.mouse_position,
-                    offset: Vec2::zero(),
-                },
-                BltEvent::KeyPressed { key, ctrl, shift } => {
-                    self.blt_keycode_to_ev(key, shift, ctrl)
-                }
-                // TODO: there's no Key::Shift/Ctrl for w/e reason
-                BltEvent::ShiftPressed => Event::Refresh,
-                BltEvent::ControlPressed => Event::Refresh,
-                // TODO: what should we do here?
-                BltEvent::KeyReleased { key, .. } => {
-                    // It's probably a mouse key.
-                    blt_keycode_to_mouse_button(key)
-                        .map(|btn| {
-                            self.buttons_pressed.remove(&btn);
-                            Event::Mouse {
-                                event: MouseEvent::Release(btn),
-                                position: self.mouse_position,
-                                offset: Vec2::zero(),
-                            }
-                        })
-                        .unwrap_or(Event::Unknown(vec![]))
-                }
-                BltEvent::ShiftReleased | BltEvent::ControlReleased => {
-                    Event::Refresh
-                }
-            }
-        } else {
-            Event::Refresh
             }
+        });
     }
 }
 

src/backend/curses/n.rs

@@ -4,27 +4,140 @@ use self::ncurses::mmask_t;
 use self::super::split_i32;
 use backend;
 use event::{Event, Key, MouseButton, MouseEvent};
-use libc;
+use theme::{Color, ColorPair, Effect};
+use utf8;
+use vec::Vec2;
+
 use std::cell::{Cell, RefCell};
 use std::collections::HashMap;
 use std::ffi::CString;
 use std::fs::File;
 use std::io;
 use std::io::{Write};
-use theme::{Color, ColorPair, Effect};
+use std::thread;
-use utf8;
+
-use vec::Vec2;
+use libc;
+use chan;
 
 pub struct Backend {
     current_style: Cell<ColorPair>,
 
     // Maps (front, back) ncurses colors to ncurses pairs
     pairs: RefCell<HashMap<(i16, i16), i16>>,
+}
 
+struct InputParser {
     key_codes: HashMap<i32, Event>,
-
     last_mouse_button: Option<MouseButton>,
-    event_queue: Vec<Event>,
+    event_sink: chan::Sender<Event>,
+}
+
+impl InputParser {
+    fn new(event_sink: chan::Sender<Event>) -> Self {
+        InputParser {
+            key_codes: initialize_keymap(),
+            last_mouse_button: None,
+            event_sink,
+        }
+    }
+
+    fn parse_next(&mut self) {
+        let ch: i32 = ncurses::getch();
+
+        // Is it a UTF-8 starting point?
+        let event = if 32 <= ch && ch <= 255 && ch != 127 {
+            utf8::read_char(ch as u8, || Some(ncurses::getch() as u8))
+                .map(Event::Char)
+                .unwrap_or_else(|e| {
+                    warn!("Error reading input: {}", e);
+                    Event::Unknown(vec![ch as u8])
+                })
+        } else {
+            self.parse_ncurses_char(ch)
+        };
+        self.event_sink.send(event);
+    }
+
+    fn parse_ncurses_char(&mut self, ch: i32) -> Event {
+        // eprintln!("Found {:?}", ncurses::keyname(ch));
+        if ch == ncurses::KEY_MOUSE {
+            self.parse_mouse_event()
+        } else {
+            self.key_codes
+                .get(&ch)
+                .cloned()
+                .unwrap_or_else(|| Event::Unknown(split_i32(ch)))
+        }
+    }
+
+    fn parse_mouse_event(&mut self) -> Event {
+        let mut mevent = ncurses::MEVENT {
+            id: 0,
+            x: 0,
+            y: 0,
+            z: 0,
+            bstate: 0,
+        };
+        if ncurses::getmouse(&mut mevent as *mut ncurses::MEVENT)
+            == ncurses::OK
+        {
+            // eprintln!("{:032b}", mevent.bstate);
+            // Currently unused
+            let _shift =
+                (mevent.bstate & ncurses::BUTTON_SHIFT as mmask_t) != 0;
+            let _alt = (mevent.bstate & ncurses::BUTTON_ALT as mmask_t) != 0;
+            let _ctrl = (mevent.bstate & ncurses::BUTTON_CTRL as mmask_t) != 0;
+
+            mevent.bstate &= !(ncurses::BUTTON_SHIFT | ncurses::BUTTON_ALT
+                | ncurses::BUTTON_CTRL)
+                as mmask_t;
+
+            let make_event = |event| Event::Mouse {
+                offset: Vec2::zero(),
+                position: Vec2::new(mevent.x as usize, mevent.y as usize),
+                event,
+            };
+
+            if mevent.bstate == ncurses::REPORT_MOUSE_POSITION as mmask_t {
+                // The event is either a mouse drag event,
+                // or a weird double-release event. :S
+                self.last_mouse_button
+                    .map(MouseEvent::Hold)
+                    .map(&make_event)
+                    .unwrap_or_else(|| Event::Unknown(vec![]))
+            } else {
+                // Identify the button
+                let mut bare_event = mevent.bstate & ((1 << 25) - 1);
+
+                let mut event = None;
+                while bare_event != 0 {
+                    let single_event = 1 << bare_event.trailing_zeros();
+                    bare_event ^= single_event;
+
+                    // Process single_event
+                    on_mouse_event(single_event as i32, |e| {
+                        if event.is_none() {
+                            event = Some(e);
+                        } else {
+                            self.event_sink.send(make_event(e));
+                        }
+                    });
+                }
+                if let Some(event) = event {
+                    if let Some(btn) = event.button() {
+                        self.last_mouse_button = Some(btn);
+                    }
+                    make_event(event)
+                } else {
+                    debug!("No event parsed?...");
+                    Event::Unknown(vec![])
+                }
+            }
+        } else {
+            debug!("Ncurses event not recognized.");
+            Event::Unknown(vec![])
+        }
+    }
 }
 
 fn find_closest_pair(pair: &ColorPair) -> (i16, i16) {
@@ -85,11 +198,6 @@ impl Backend {
         let c = Backend {
             current_style: Cell::new(ColorPair::from_256colors(0, 0)),
             pairs: RefCell::new(HashMap::new()),
-
-            last_mouse_button: None,
-            event_queue: Vec::new(),
-
-            key_codes: initialize_keymap(),
         };
 
         Box::new(c)
@@ -139,86 +247,7 @@ impl Backend {
         ncurses::attron(style);
     }
 
-    fn parse_mouse_event(&mut self) -> Event {
-        let mut mevent = ncurses::MEVENT {
-            id: 0,
-            x: 0,
-            y: 0,
-            z: 0,
-            bstate: 0,
-        };
-        if ncurses::getmouse(&mut mevent as *mut ncurses::MEVENT)
-            == ncurses::OK
-        {
-            // eprintln!("{:032b}", mevent.bstate);
-            // Currently unused
-            let _shift =
-                (mevent.bstate & ncurses::BUTTON_SHIFT as mmask_t) != 0;
-            let _alt = (mevent.bstate & ncurses::BUTTON_ALT as mmask_t) != 0;
-            let _ctrl = (mevent.bstate & ncurses::BUTTON_CTRL as mmask_t) != 0;
 
-            mevent.bstate &= !(ncurses::BUTTON_SHIFT | ncurses::BUTTON_ALT
-                | ncurses::BUTTON_CTRL)
-                as mmask_t;
-
-            let make_event = |event| Event::Mouse {
-                offset: Vec2::zero(),
-                position: Vec2::new(mevent.x as usize, mevent.y as usize),
-                event,
-            };
-
-            if mevent.bstate == ncurses::REPORT_MOUSE_POSITION as mmask_t {
-                // The event is either a mouse drag event,
-                // or a weird double-release event. :S
-                self.last_mouse_button
-                    .map(MouseEvent::Hold)
-                    .map(&make_event)
-                    .unwrap_or_else(|| Event::Unknown(vec![]))
-            } else {
-                // Identify the button
-                let mut bare_event = mevent.bstate & ((1 << 25) - 1);
-
-                let mut event = None;
-                while bare_event != 0 {
-                    let single_event = 1 << bare_event.trailing_zeros();
-                    bare_event ^= single_event;
-
-                    // Process single_event
-                    on_mouse_event(single_event as i32, |e| {
-                        if event.is_none() {
-                            event = Some(e);
-                        } else {
-                            self.event_queue.push(make_event(e));
-                        }
-                    });
-                }
-                if let Some(event) = event {
-                    if let Some(btn) = event.button() {
-                        self.last_mouse_button = Some(btn);
-                    }
-                    make_event(event)
-                } else {
-                    debug!("No event parsed?...");
-                    Event::Unknown(vec![])
-                }
-            }
-        } else {
-            debug!("Ncurses event not recognized.");
-            Event::Unknown(vec![])
-        }
-    }
-
-    fn parse_ncurses_char(&mut self, ch: i32) -> Event {
-        // eprintln!("Found {:?}", ncurses::keyname(ch));
-        if ch == ncurses::KEY_MOUSE {
-            self.parse_mouse_event()
-        } else {
-            self.key_codes
-                .get(&ch)
-                .cloned()
-                .unwrap_or_else(|| Event::Unknown(split_i32(ch)))
-        }
-    }
 }
 
 impl backend::Backend for Backend {
@@ -233,6 +262,18 @@ impl backend::Backend for Backend {
         ncurses::has_colors()
     }
 
+    fn start_input_thread(&mut self, event_sink: chan::Sender<Event>) {
+        let mut parser = InputParser::new(event_sink);
+
+        // Start an input thread
+        thread::spawn(move || {
+            // TODO: use an atomic boolean to stop the thread on finish
+            loop {
+                parser.parse_next();
+            }
+        });
+    }
+
     fn finish(&mut self) {
         write_to_tty(b"\x1B[?1002l").unwrap();
         ncurses::endwin();
@@ -287,32 +328,6 @@ impl backend::Backend for Backend {
     fn print_at(&self, pos: Vec2, text: &str) {
         ncurses::mvaddstr(pos.y as i32, pos.x as i32, text);
     }
-
-    fn poll_event(&mut self) -> Event {
-        self.event_queue.pop().unwrap_or_else(|| {
-            let ch: i32 = ncurses::getch();
-
-            // Is it a UTF-8 starting point?
-            if 32 <= ch && ch <= 255 && ch != 127 {
-                utf8::read_char(ch as u8, || Some(ncurses::getch() as u8))
-                    .map(Event::Char)
-                    .unwrap_or_else(|e| {
-                        warn!("Error reading input: {}", e);
-                        Event::Unknown(vec![ch as u8])
-                    })
-            } else {
-                self.parse_ncurses_char(ch)
-            }
-        })
-    }
-
-    fn set_refresh_rate(&mut self, fps: u32) {
-        if fps == 0 {
-            ncurses::timeout(-1);
-        } else {
-            ncurses::timeout(1000 / fps as i32);
-        }
-    }
 }
 
 /// Returns the Key enum corresponding to the given ncurses event.

src/backend/curses/pan.rs

@@ -9,235 +9,44 @@ use std::collections::HashMap;
 use std::io::{stdout, Write};
 use theme::{Color, ColorPair, Effect};
 use vec::Vec2;
+use std::sync::Arc;
+use chan;
+use std::thread;
 
 pub struct Backend {
     // Used
     current_style: Cell<ColorPair>,
     pairs: RefCell<HashMap<(i16, i16), i32>>,
 
-    key_codes: HashMap<i32, Event>,
-
-    last_mouse_button: Option<MouseButton>,
-    event_queue: Vec<Event>,
-
     // pancurses needs a handle to the current window.
-    window: pancurses::Window,
+    window: Arc<pancurses::Window>,
 }
 
-fn find_closest_pair(pair: &ColorPair) -> (i16, i16) {
+struct InputParser {
-    super::find_closest_pair(pair, pancurses::COLORS() as i16)
+    key_codes: HashMap<i32, Event>,
+    last_mouse_button: Option<MouseButton>,
+    event_sink: chan::Sender<Event>,
+    window: Arc<pancurses::Window>,
 }
 
-impl Backend {
+// Ncurses (and pancurses) are not thread-safe
-    pub fn init() -> Box<Self> {
+// (writing from two threads might cause garbage).
-        ::std::env::set_var("ESCDELAY", "25");
+// BUT it's probably fine to read while we write.
+// So `InputParser` will only read, and `Backend` will mostly write.
+unsafe impl Send for InputParser {}
 
-        let window = pancurses::initscr();
+impl InputParser {
-        window.keypad(true);
+    fn new(event_sink: chan::Sender<Event>, window: Arc<pancurses::Window>) -> Self {
-        pancurses::noecho();
+        InputParser {
-        pancurses::cbreak();
-        pancurses::start_color();
-        pancurses::use_default_colors();
-        pancurses::curs_set(0);
-        pancurses::mouseinterval(0);
-        pancurses::mousemask(
-            pancurses::ALL_MOUSE_EVENTS | pancurses::REPORT_MOUSE_POSITION,
-            ::std::ptr::null_mut(),
-        );
-
-        // This asks the terminal to provide us with mouse drag events
-        // (Mouse move when a button is pressed).
-        // Replacing 1002 with 1003 would give us ANY mouse move.
-        print!("\x1B[?1002h");
-        stdout().flush().expect("could not flush stdout");
-
-        let c = Backend {
-            current_style: Cell::new(ColorPair::from_256colors(0, 0)),
-            pairs: RefCell::new(HashMap::new()),
-            window: window,
-            last_mouse_button: None,
-            event_queue: Vec::new(),
             key_codes: initialize_keymap(),
-        };
+            last_mouse_button: None,
-
+            event_sink,
-        Box::new(c)
+            window,
-    }
-
-    /// Save a new color pair.
-    fn insert_color(
-        &self,
-        pairs: &mut HashMap<(i16,i16), i32>,
-        (front, back): (i16, i16),
-    ) -> i32 {
-        let n = 1 + pairs.len() as i32;
-
-        // TODO: when COLORS_PAIRS is available...
-        let target = if 256 > n {
-            // We still have plenty of space for everyone.
-            n
-        } else {
-            // The world is too small for both of us.
-            let target = n - 1;
-            // Remove the mapping to n-1
-            pairs.retain(|_, &mut v| v != target);
-            target
-        };
-        pairs.insert((front, back), target);
-        pancurses::init_pair(target as i16, front, back);
-        target
-    }
-
-    /// Checks the pair in the cache, or re-define a color if needed.
-    fn get_or_create(&self, pair: ColorPair) -> i32 {
-        let mut pairs = self.pairs.borrow_mut();
-        let pair = find_closest_pair(&pair);
-
-        // Find if we have this color in stock
-        if pairs.contains_key(&pair) {
-            // We got it!
-            pairs[&pair]
-        } else {
-            self.insert_color(&mut *pairs, pair)
         }
     }
 
-    fn set_colors(&self, pair: ColorPair) {
+    fn parse_next(&mut self) {
-        let i = self.get_or_create(pair);
+        let event = if let Some(ev) = self.window.getch() {
-
-        self.current_style.set(pair);
-        let style = pancurses::COLOR_PAIR(i as pancurses::chtype);
-        self.window.attron(style);
-    }
-
-    fn parse_mouse_event(&mut self) -> Event {
-        let mut mevent = match pancurses::getmouse() {
-            Err(code) => return Event::Unknown(split_i32(code)),
-            Ok(event) => event,
-        };
-
-        let _shift = (mevent.bstate & pancurses::BUTTON_SHIFT as mmask_t) != 0;
-        let _alt = (mevent.bstate & pancurses::BUTTON_ALT as mmask_t) != 0;
-        let _ctrl = (mevent.bstate & pancurses::BUTTON_CTRL as mmask_t) != 0;
-
-        mevent.bstate &= !(pancurses::BUTTON_SHIFT | pancurses::BUTTON_ALT
-            | pancurses::BUTTON_CTRL) as mmask_t;
-
-        let make_event = |event| Event::Mouse {
-            offset: Vec2::zero(),
-            position: Vec2::new(mevent.x as usize, mevent.y as usize),
-            event: event,
-        };
-
-        if mevent.bstate == pancurses::REPORT_MOUSE_POSITION as mmask_t {
-            // The event is either a mouse drag event,
-            // or a weird double-release event. :S
-            self.last_mouse_button
-                .map(MouseEvent::Hold)
-                .map(&make_event)
-                .unwrap_or_else(|| {
-                    debug!("We got a mouse drag, but no last mouse pressed?");
-                    Event::Unknown(vec![])
-                })
-        } else {
-            // Identify the button
-            let mut bare_event = mevent.bstate & ((1 << 25) - 1);
-
-            let mut event = None;
-            while bare_event != 0 {
-                let single_event = 1 << bare_event.trailing_zeros();
-                bare_event ^= single_event;
-
-                // Process single_event
-                on_mouse_event(single_event, |e| {
-                    if event.is_none() {
-                        event = Some(e);
-                    } else {
-                        self.event_queue.push(make_event(e));
-                    }
-                });
-            }
-            if let Some(event) = event {
-                if let Some(btn) = event.button() {
-                    self.last_mouse_button = Some(btn);
-                }
-                make_event(event)
-            } else {
-                debug!("No event parsed?...");
-                Event::Unknown(vec![])
-            }
-        }
-    }
-}
-
-impl backend::Backend for Backend {
-    fn screen_size(&self) -> Vec2 {
-        // Coordinates are reversed here
-        let (y, x) = self.window.get_max_yx();
-        (x, y).into()
-    }
-
-    fn has_colors(&self) -> bool {
-        pancurses::has_colors()
-    }
-
-    fn finish(&mut self) {
-        print!("\x1B[?1002l");
-        stdout().flush().expect("could not flush stdout");
-        pancurses::endwin();
-    }
-
-    fn set_color(&self, colors: ColorPair) -> ColorPair {
-        let current = self.current_style.get();
-
-        if current != colors {
-            self.set_colors(colors);
-        }
-
-        current
-    }
-
-    fn set_effect(&self, effect: Effect) {
-        let style = match effect {
-            Effect::Simple => pancurses::Attribute::Normal,
-            Effect::Reverse => pancurses::Attribute::Reverse,
-            Effect::Bold => pancurses::Attribute::Bold,
-            Effect::Italic => pancurses::Attribute::Italic,
-            Effect::Underline => pancurses::Attribute::Underline,
-        };
-        self.window.attron(style);
-    }
-
-    fn unset_effect(&self, effect: Effect) {
-        let style = match effect {
-            Effect::Simple => pancurses::Attribute::Normal,
-            Effect::Reverse => pancurses::Attribute::Reverse,
-            Effect::Bold => pancurses::Attribute::Bold,
-            Effect::Italic => pancurses::Attribute::Italic,
-            Effect::Underline => pancurses::Attribute::Underline,
-        };
-        self.window.attroff(style);
-    }
-
-    fn clear(&self, color: Color) {
-        let id = self.get_or_create(ColorPair {
-            front: color,
-            back: color,
-        });
-        self.window.bkgd(pancurses::ColorPair(id as u8));
-        self.window.clear();
-    }
-
-    fn refresh(&mut self) {
-        self.window.refresh();
-    }
-
-    fn print_at(&self, pos: Vec2, text: &str) {
-        self.window.mvaddstr(pos.y as i32, pos.x as i32, text);
-    }
-
-    fn poll_event(&mut self) -> Event {
-        self.event_queue.pop().unwrap_or_else(|| {
-            if let Some(ev) = self.window.getch() {
             match ev {
                 pancurses::Input::Character('\n') => {
                     Event::Key(Key::Enter)
@@ -396,16 +205,229 @@ impl backend::Backend for Backend {
             }
         } else {
             Event::Refresh
-            }
+        };
-        })
+        self.event_sink.send(event);
     }
 
-    fn set_refresh_rate(&mut self, fps: u32) {
+    fn parse_mouse_event(&mut self) -> Event {
-        if fps == 0 {
+        let mut mevent = match pancurses::getmouse() {
-            self.window.timeout(-1);
+            Err(code) => return Event::Unknown(split_i32(code)),
+            Ok(event) => event,
+        };
+
+        let _shift = (mevent.bstate & pancurses::BUTTON_SHIFT as mmask_t) != 0;
+        let _alt = (mevent.bstate & pancurses::BUTTON_ALT as mmask_t) != 0;
+        let _ctrl = (mevent.bstate & pancurses::BUTTON_CTRL as mmask_t) != 0;
+
+        mevent.bstate &= !(pancurses::BUTTON_SHIFT | pancurses::BUTTON_ALT
+            | pancurses::BUTTON_CTRL) as mmask_t;
+
+        let make_event = |event| Event::Mouse {
+            offset: Vec2::zero(),
+            position: Vec2::new(mevent.x as usize, mevent.y as usize),
+            event: event,
+        };
+
+        if mevent.bstate == pancurses::REPORT_MOUSE_POSITION as mmask_t {
+            // The event is either a mouse drag event,
+            // or a weird double-release event. :S
+            self.last_mouse_button
+                .map(MouseEvent::Hold)
+                .map(&make_event)
+                .unwrap_or_else(|| {
+                    debug!("We got a mouse drag, but no last mouse pressed?");
+                    Event::Unknown(vec![])
+                })
         } else {
-            self.window.timeout(1000 / fps as i32);
+            // Identify the button
+            let mut bare_event = mevent.bstate & ((1 << 25) - 1);
+
+            let mut event = None;
+            while bare_event != 0 {
+                let single_event = 1 << bare_event.trailing_zeros();
+                bare_event ^= single_event;
+
+                // Process single_event
+                on_mouse_event(single_event, |e| {
+                    if event.is_none() {
+                        event = Some(e);
+                    } else {
+                        self.event_sink.send(make_event(e));
                     }
+                });
+            }
+            if let Some(event) = event {
+                if let Some(btn) = event.button() {
+                    self.last_mouse_button = Some(btn);
+                }
+                make_event(event)
+            } else {
+                debug!("No event parsed?...");
+                Event::Unknown(vec![])
+            }
+        }
+    }
+}
+
+fn find_closest_pair(pair: &ColorPair) -> (i16, i16) {
+    super::find_closest_pair(pair, pancurses::COLORS() as i16)
+}
+
+impl Backend {
+    pub fn init() -> Box<Self> {
+        ::std::env::set_var("ESCDELAY", "25");
+
+        let window = pancurses::initscr();
+        window.keypad(true);
+        pancurses::noecho();
+        pancurses::cbreak();
+        pancurses::start_color();
+        pancurses::use_default_colors();
+        pancurses::curs_set(0);
+        pancurses::mouseinterval(0);
+        pancurses::mousemask(
+            pancurses::ALL_MOUSE_EVENTS | pancurses::REPORT_MOUSE_POSITION,
+            ::std::ptr::null_mut(),
+        );
+
+        // This asks the terminal to provide us with mouse drag events
+        // (Mouse move when a button is pressed).
+        // Replacing 1002 with 1003 would give us ANY mouse move.
+        print!("\x1B[?1002h");
+        stdout().flush().expect("could not flush stdout");
+
+        let c = Backend {
+            current_style: Cell::new(ColorPair::from_256colors(0, 0)),
+            pairs: RefCell::new(HashMap::new()),
+            window: Arc::new(window),
+        };
+
+        Box::new(c)
+    }
+
+    /// Save a new color pair.
+    fn insert_color(
+        &self,
+        pairs: &mut HashMap<(i16,i16), i32>,
+        (front, back): (i16, i16),
+    ) -> i32 {
+        let n = 1 + pairs.len() as i32;
+
+        // TODO: when COLORS_PAIRS is available...
+        let target = if 256 > n {
+            // We still have plenty of space for everyone.
+            n
+        } else {
+            // The world is too small for both of us.
+            let target = n - 1;
+            // Remove the mapping to n-1
+            pairs.retain(|_, &mut v| v != target);
+            target
+        };
+        pairs.insert((front, back), target);
+        pancurses::init_pair(target as i16, front, back);
+        target
+    }
+
+    /// Checks the pair in the cache, or re-define a color if needed.
+    fn get_or_create(&self, pair: ColorPair) -> i32 {
+        let mut pairs = self.pairs.borrow_mut();
+        let pair = find_closest_pair(&pair);
+
+        // Find if we have this color in stock
+        if pairs.contains_key(&pair) {
+            // We got it!
+            pairs[&pair]
+        } else {
+            self.insert_color(&mut *pairs, pair)
+        }
+    }
+
+    fn set_colors(&self, pair: ColorPair) {
+        let i = self.get_or_create(pair);
+
+        self.current_style.set(pair);
+        let style = pancurses::COLOR_PAIR(i as pancurses::chtype);
+        self.window.attron(style);
+    }
+
+}
+
+impl backend::Backend for Backend {
+    fn screen_size(&self) -> Vec2 {
+        // Coordinates are reversed here
+        let (y, x) = self.window.get_max_yx();
+        (x, y).into()
+    }
+
+    fn has_colors(&self) -> bool {
+        pancurses::has_colors()
+    }
+
+    fn finish(&mut self) {
+        print!("\x1B[?1002l");
+        stdout().flush().expect("could not flush stdout");
+        pancurses::endwin();
+    }
+
+    fn set_color(&self, colors: ColorPair) -> ColorPair {
+        let current = self.current_style.get();
+
+        if current != colors {
+            self.set_colors(colors);
+        }
+
+        current
+    }
+
+    fn set_effect(&self, effect: Effect) {
+        let style = match effect {
+            Effect::Simple => pancurses::Attribute::Normal,
+            Effect::Reverse => pancurses::Attribute::Reverse,
+            Effect::Bold => pancurses::Attribute::Bold,
+            Effect::Italic => pancurses::Attribute::Italic,
+            Effect::Underline => pancurses::Attribute::Underline,
+        };
+        self.window.attron(style);
+    }
+
+    fn unset_effect(&self, effect: Effect) {
+        let style = match effect {
+            Effect::Simple => pancurses::Attribute::Normal,
+            Effect::Reverse => pancurses::Attribute::Reverse,
+            Effect::Bold => pancurses::Attribute::Bold,
+            Effect::Italic => pancurses::Attribute::Italic,
+            Effect::Underline => pancurses::Attribute::Underline,
+        };
+        self.window.attroff(style);
+    }
+
+    fn clear(&self, color: Color) {
+        let id = self.get_or_create(ColorPair {
+            front: color,
+            back: color,
+        });
+        self.window.bkgd(pancurses::ColorPair(id as u8));
+        self.window.clear();
+    }
+
+    fn refresh(&mut self) {
+        self.window.refresh();
+    }
+
+    fn print_at(&self, pos: Vec2, text: &str) {
+        self.window.mvaddstr(pos.y as i32, pos.x as i32, text);
+    }
+
+    fn start_input_thread(&mut self, event_sink: chan::Sender<Event>) {
+        let mut input_parser = InputParser::new(event_sink, Arc::clone(&self.window));
+
+        thread::spawn(move || {
+            loop {
+                input_parser.parse_next();
+            }
+        });
+
     }
 }
 

src/backend/dummy.rs

@@ -4,6 +4,10 @@ use theme;
 use event;
 use vec::Vec2;
 
+use std::thread;
+
+use chan;
+
 pub struct Backend;
 
 impl Backend {
@@ -28,16 +32,14 @@ impl backend::Backend for Backend {
         (1, 1).into()
     }
 
-    fn poll_event(&mut self) -> event::Event {
+    fn start_input_thread(&mut self, event_sink: chan::Sender<event::Event>) {
-        event::Event::Exit
+        thread::spawn(move || event_sink.send(event::Event::Exit));
     }
 
     fn print_at(&self, _: Vec2, _: &str) {}
 
     fn clear(&self, _: theme::Color) {}
 
-    fn set_refresh_rate(&mut self, _: u32) {}
-
     // This sets the Colours and returns the previous colours
     // to allow you to set them back when you're done.
     fn set_color(&self, colors: theme::ColorPair) -> theme::ColorPair {

src/backend/mod.rs

@@ -10,6 +10,8 @@
 use event;
 use theme;
 
+use chan::Sender;
+
 use vec::Vec2;
 
 pub mod dummy;
@@ -27,6 +29,8 @@ pub trait Backend {
     /// This should clear any state in the terminal.
     fn finish(&mut self);
 
+    fn start_input_thread(&mut self, event_sink: Sender<event::Event>);
+
     /// Refresh the screen.
     fn refresh(&mut self);
 
@@ -36,8 +40,8 @@ pub trait Backend {
     /// Returns the screen size.
     fn screen_size(&self) -> Vec2;
 
-    /// Main input method
+    // /// Gets a receiver for input events.
-    fn poll_event(&mut self) -> event::Event;
+    // fn event_receiver(&mut self) -> Receiver<event::Event>;
 
     /// Main method used for printing
     fn print_at(&self, pos: Vec2, text: &str);
@@ -45,11 +49,6 @@ pub trait Backend {
     /// Clears the screen with the given color.
     fn clear(&self, color: theme::Color);
 
-    /// Sets the refresh rate for the backend.
-    ///
-    /// If no event is detected in the interval, send an `Event::Refresh`.
-    fn set_refresh_rate(&mut self, fps: u32);
-
     /// Starts using a new color.
     ///
     /// This should return the previously active color.

src/backend/termion.rs

@@ -28,52 +28,20 @@ use vec::Vec2;
 pub struct Backend {
     terminal: AlternateScreen<MouseTerminal<RawTerminal<Stdout>>>,
     current_style: Cell<theme::ColorPair>,
+}
+
+struct InputParser {
     input: chan::Receiver<TEvent>,
     resize: chan::Receiver<chan_signal::Signal>,
-    timeout: Option<u32>,
+    event_sink: chan::Sender<Event>,
     last_button: Option<MouseButton>,
 }
 
-trait Effectable {
+impl InputParser {
-    fn on(&self);
+    fn new(event_sink: chan::Sender<Event>) -> Self {
-    fn off(&self);
-}
-
-impl Effectable for theme::Effect {
-    fn on(&self) {
-        match *self {
-            theme::Effect::Simple => (),
-            theme::Effect::Reverse => print!("{}", tstyle::Invert),
-            theme::Effect::Bold => print!("{}", tstyle::Bold),
-            theme::Effect::Italic => print!("{}", tstyle::Italic),
-            theme::Effect::Underline => print!("{}", tstyle::Underline),
-        }
-    }
-
-    fn off(&self) {
-        match *self {
-            theme::Effect::Simple => (),
-            theme::Effect::Reverse => print!("{}", tstyle::NoInvert),
-            theme::Effect::Bold => print!("{}", tstyle::NoBold),
-            theme::Effect::Italic => print!("{}", tstyle::NoItalic),
-            theme::Effect::Underline => print!("{}", tstyle::NoUnderline),
-        }
-    }
-}
-
-impl Backend {
-    pub fn init() -> Box<Self> {
-        print!("{}", termion::cursor::Hide);
-
-        let resize = chan_signal::notify(&[chan_signal::Signal::WINCH]);
-
-        // TODO: lock stdout
-        let terminal = AlternateScreen::from(MouseTerminal::from(
-            ::std::io::stdout().into_raw_mode().unwrap(),
-        ));
-
         let (sender, receiver) = chan::async();
 
+        // Fill the input channel
         thread::spawn(move || {
             for key in ::std::io::stdin().events() {
                 if let Ok(key) = key {
@@ -82,22 +50,34 @@ impl Backend {
             }
         });
 
-        let c = Backend {
+        InputParser {
-            terminal: terminal,
+            resize: chan_signal::notify(&[chan_signal::Signal::WINCH]),
-            current_style: Cell::new(theme::ColorPair::from_256colors(0, 0)),
+            event_sink,
-            input: receiver,
-            resize: resize,
-            timeout: None,
             last_button: None,
-        };
+            input: receiver,
-
+        }
-        Box::new(c)
     }
 
-    fn apply_colors(&self, colors: theme::ColorPair) {
+    fn next_event(&mut self) -> Event {
-        with_color(&colors.front, |c| print!("{}", tcolor::Fg(c)));
+        let result;
-        with_color(&colors.back, |c| print!("{}", tcolor::Bg(c)));
+        {
+            let input = &self.input;
+            let resize = &self.resize;
+
+            chan_select!{
+                resize.recv() => return Event::WindowResize,
+                input.recv() -> input => result = Some(input.unwrap()),
             }
+        }
+
+        self.map_key(result.unwrap())
+    }
+
+    fn parse_next(&mut self) {
+        let event = self.next_event();
+        self.event_sink.send(event);
+    }
+
     fn map_key(&mut self, event: TEvent) -> Event {
         match event {
             TEvent::Unsupported(bytes) => Event::Unknown(bytes),
@@ -173,6 +153,58 @@ impl Backend {
     }
 }
 
+trait Effectable {
+    fn on(&self);
+    fn off(&self);
+}
+
+impl Effectable for theme::Effect {
+    fn on(&self) {
+        match *self {
+            theme::Effect::Simple => (),
+            theme::Effect::Reverse => print!("{}", tstyle::Invert),
+            theme::Effect::Bold => print!("{}", tstyle::Bold),
+            theme::Effect::Italic => print!("{}", tstyle::Italic),
+            theme::Effect::Underline => print!("{}", tstyle::Underline),
+        }
+    }
+
+    fn off(&self) {
+        match *self {
+            theme::Effect::Simple => (),
+            theme::Effect::Reverse => print!("{}", tstyle::NoInvert),
+            theme::Effect::Bold => print!("{}", tstyle::NoBold),
+            theme::Effect::Italic => print!("{}", tstyle::NoItalic),
+            theme::Effect::Underline => print!("{}", tstyle::NoUnderline),
+        }
+    }
+}
+
+impl Backend {
+    pub fn init() -> Box<Self> {
+        print!("{}", termion::cursor::Hide);
+
+
+        // TODO: lock stdout
+        let terminal = AlternateScreen::from(MouseTerminal::from(
+            ::std::io::stdout().into_raw_mode().unwrap(),
+        ));
+
+
+        let c = Backend {
+            terminal: terminal,
+            current_style: Cell::new(theme::ColorPair::from_256colors(0, 0)),
+        };
+
+        Box::new(c)
+    }
+
+    fn apply_colors(&self, colors: theme::ColorPair) {
+        with_color(&colors.front, |c| print!("{}", tcolor::Fg(c)));
+        with_color(&colors.back, |c| print!("{}", tcolor::Bg(c)));
+    }
+}
+
 impl backend::Backend for Backend {
     fn finish(&mut self) {
         print!("{}{}", termion::cursor::Show, termion::cursor::Goto(1, 1));
@@ -233,32 +265,13 @@ impl backend::Backend for Backend {
         );
     }
 
-    fn set_refresh_rate(&mut self, fps: u32) {
+    fn start_input_thread(&mut self, event_sink: chan::Sender<Event>) {
-        self.timeout = Some(1000 / fps as u32);
+        let mut parser = InputParser::new(event_sink);
+        thread::spawn(move || {
+            loop {
+                parser.parse_next();
             }
-
+        });
-    fn poll_event(&mut self) -> Event {
-        let result;
-        {
-            let input = &self.input;
-            let resize = &self.resize;
-
-            if let Some(timeout) = self.timeout {
-                let timeout = chan::after_ms(timeout);
-                chan_select!{
-                    timeout.recv() => return Event::Refresh,
-                    resize.recv() => return Event::WindowResize,
-                    input.recv() -> input => result = Some(input.unwrap()),
-                }
-            } else {
-                chan_select!{
-                    resize.recv() => return Event::WindowResize,
-                    input.recv() -> input => result = Some(input.unwrap()),
-                }
-            }
-        }
-
-        self.map_key(result.unwrap())
     }
 }
 

src/cursive.rs

@@ -1,16 +1,57 @@
 use backend;
+use chan;
 use direction;
 use event::{Callback, Event, EventResult};
 use printer::Printer;
 use std::any::Any;
 use std::collections::HashMap;
 use std::path::Path;
-use std::sync::mpsc;
 use theme;
 use vec::Vec2;
 use view::{self, Finder, IntoBoxedView, Position, View};
 use views::{self, LayerPosition};
 
+/// Central part of the cursive library.
+///
+/// It initializes ncurses on creation and cleans up on drop.
+/// To use it, you should populate it with views, layouts and callbacks,
+/// then start the event loop with run().
+///
+/// It uses a list of screen, with one screen active at a time.
+pub struct Cursive {
+    theme: theme::Theme,
+    screens: Vec<views::StackView>,
+    global_callbacks: HashMap<Event, Vec<Callback>>,
+    menubar: views::Menubar,
+
+    // Last layer sizes of the stack view.
+    // If it changed, clear the screen.
+    last_sizes: Vec<Vec2>,
+
+    fps: u32,
+
+    active_screen: ScreenId,
+
+    running: bool,
+
+    backend: Box<backend::Backend>,
+
+    cb_source: chan::Receiver<Box<CbFunc>>,
+    cb_sink: chan::Sender<Box<CbFunc>>,
+
+    event_source: chan::Receiver<Event>,
+}
+
+/// Describes one of the possible interruptions we should handle.
+enum Interruption {
+    /// An input event was received
+    Event(Event),
+    /// A callback was received
+    Callback(Box<CbFunc>),
+    /// A timeout ran out
+    Timeout,
+}
+
 /// Identifies a screen in the cursive root.
 pub type ScreenId = usize;
 
@@ -46,57 +87,45 @@ impl Default for Cursive {
     }
 }
 
-#[cfg(all(not(feature = "termion"), not(feature = "pancurses"), feature = "bear-lib-terminal"))]
+#[cfg(
+    all(
+        not(feature = "termion"),
+        not(feature = "pancurses"),
+        feature = "bear-lib-terminal"
+    )
+)]
 impl Default for Cursive {
     fn default() -> Self {
         Self::blt()
     }
 }
 
-#[cfg(all(not(feature = "termion"), not(feature = "pancurses"), not(feature = "bear-lib-terminal"), feature = "ncurses"))]
+#[cfg(
+    all(
+        not(feature = "termion"),
+        not(feature = "pancurses"),
+        not(feature = "bear-lib-terminal"),
+        feature = "ncurses"
+    )
+)]
 impl Default for Cursive {
     fn default() -> Self {
         Self::ncurses()
     }
 }
 
-/// Central part of the cursive library.
-///
-/// It initializes ncurses on creation and cleans up on drop.
-/// To use it, you should populate it with views, layouts and callbacks,
-/// then start the event loop with run().
-///
-/// It uses a list of screen, with one screen active at a time.
-pub struct Cursive {
-    theme: theme::Theme,
-    screens: Vec<views::StackView>,
-    global_callbacks: HashMap<Event, Vec<Callback>>,
-    menubar: views::Menubar,
-
-    // Last layer sizes of the stack view.
-    // If it changed, clear the screen.
-    last_sizes: Vec<Vec2>,
-
-    active_screen: ScreenId,
-
-    running: bool,
-
-    backend: Box<backend::Backend>,
-
-    cb_source: mpsc::Receiver<Box<CbFunc>>,
-    cb_sink: mpsc::Sender<Box<CbFunc>>,
-}
-
 impl Cursive {
     /// Creates a new Cursive root, and initialize the back-end.
-    pub fn new(backend: Box<backend::Backend>) -> Self {
+    pub fn new(mut backend: Box<backend::Backend>) -> Self {
         let theme = theme::load_default();
-        // theme.activate(&mut backend);
-        // let theme = theme::load_theme("assets/style.toml").unwrap();
 
-        let (tx, rx) = mpsc::channel();
+        let (cb_sink, cb_source) = chan::async();
+        let (event_sink, event_source) = chan::async();
+
+        backend.start_input_thread(event_sink);
 
         Cursive {
+            fps: 0,
             theme: theme,
             screens: vec![views::StackView::new()],
             last_sizes: Vec::new(),
@@ -104,8 +133,9 @@ impl Cursive {
             menubar: views::Menubar::new(),
             active_screen: 0,
             running: true,
-            cb_source: rx,
+            cb_source,
-            cb_sink: tx,
+            cb_sink,
+            event_source,
             backend: backend,
         }
     }
@@ -167,7 +197,7 @@ impl Cursive {
     /// ```
     ///
     /// [`set_fps`]: #method.set_fps
-    pub fn cb_sink(&self) -> &mpsc::Sender<Box<CbFunc>> {
+    pub fn cb_sink(&self) -> &chan::Sender<Box<CbFunc>> {
         &self.cb_sink
     }
 
@@ -261,7 +291,7 @@ impl Cursive {
     ///
     /// `filename` must point to a valid toml file.
     pub fn load_theme_file<P: AsRef<Path>>(
-        &mut self, filename: P
+        &mut self, filename: P,
     ) -> Result<(), theme::Error> {
         self.set_theme(try!(theme::load_theme_file(filename)));
         Ok(())
@@ -286,7 +316,8 @@ impl Cursive {
     ///
     /// [`cb_sink`]: #method.cb_sink
     pub fn set_fps(&mut self, fps: u32) {
-        self.backend.set_refresh_rate(fps)
+        // self.backend.set_refresh_rate(fps)
+        self.fps = fps;
     }
 
     /// Returns a reference to the currently active screen.
@@ -366,7 +397,7 @@ impl Cursive {
     /// # }
     /// ```
     pub fn call_on<V, F, R>(
-        &mut self, sel: &view::Selector, callback: F
+        &mut self, sel: &view::Selector, callback: F,
     ) -> Option<R>
     where
         V: View + Any,
@@ -532,11 +563,42 @@ impl Cursive {
 
     /// Convenient stub forwarding layer repositioning.
     pub fn reposition_layer(
-        &mut self, layer: LayerPosition, position: Position
+        &mut self, layer: LayerPosition, position: Position,
     ) {
         self.screen_mut().reposition_layer(layer, position);
     }
 
+    // Wait until something happens.
+    fn poll(&mut self) -> Interruption {
+        let input_channel = &self.event_source;
+        let cb_channel = &self.cb_source;
+
+        if self.fps > 0 {
+            let timeout =  1000 / self.fps;
+            let timeout = chan::after_ms(timeout);
+            chan_select! {
+                input_channel.recv() -> input => {
+                    return Interruption::Event(input.unwrap())
+                },
+                cb_channel.recv() -> cb => {
+                    return Interruption::Callback(cb.unwrap())
+                },
+                timeout.recv() => {
+                    return Interruption::Timeout;
+                },
+            }
+        } else {
+            chan_select! {
+                input_channel.recv() -> input => {
+                    return Interruption::Event(input.unwrap())
+                },
+                cb_channel.recv() -> cb => {
+                    return Interruption::Callback(cb.unwrap())
+                },
+            }
+        }
+    }
+
     // Handles a key event when it was ignored by the current view
     fn on_event(&mut self, event: Event) {
         let cb_list = match self.global_callbacks.get(&event) {
@@ -632,10 +694,6 @@ impl Cursive {
     ///
     /// [`run(&mut self)`]: #method.run
     pub fn step(&mut self) {
-        while let Ok(cb) = self.cb_source.try_recv() {
-            cb.call_box(self);
-        }
-
         // Do we need to redraw everytime?
         // Probably, actually.
         // TODO: Do we need to re-layout everytime?
@@ -647,8 +705,8 @@ impl Cursive {
         self.backend.refresh();
 
         // Wait for next event.
-        // (If set_fps was called, this returns -1 now and then)
+        match self.poll() {
-        let event = self.backend.poll_event();
+            Interruption::Event(event) => {
                 if event == Event::Exit {
                     self.quit();
                 }
@@ -678,7 +736,9 @@ impl Cursive {
                     self.menubar.on_event(event).process(self);
                 } else {
                     let offset = if self.menubar.autohide { 0 } else { 1 };
-            match self.screen_mut().on_event(event.relativized((0, offset))) {
+                    match self.screen_mut()
+                        .on_event(event.relativized((0, offset)))
+                    {
                         // If the event was ignored,
                         // it is our turn to play with it.
                         EventResult::Ignored => self.on_event(event),
@@ -686,6 +746,13 @@ impl Cursive {
                         EventResult::Consumed(Some(cb)) => cb(self),
                     }
                 }
+            },
+            Interruption::Callback(cb) => {
+                cb.call_box(self);
+            },
+            Interruption::Timeout => {
+            }
+        }
     }
 
     /// Stops the event loop.

src/lib.rs

@@ -67,6 +67,8 @@ extern crate enum_map;
 extern crate enumset;
 #[macro_use]
 extern crate log;
+#[macro_use]
+extern crate chan;
 
 #[cfg(any(feature = "ncurses", feature = "pancurses"))]
 #[macro_use]
@@ -80,10 +82,6 @@ extern crate unicode_segmentation;
 extern crate unicode_width;
 extern crate xi_unicode;
 
-#[cfg(feature = "termion")]
-#[macro_use]
-extern crate chan;
-
 macro_rules! new_default(
     ($c:ty) => {
         impl Default for $c {