Add wakeup support (#7)

* Add wakeup support

This also fixes a bug (the `glutin_handle_basic_input` callback was never actually given mutable access to the `BasicInput`, so there's no way it could have set `BasicInput::wait` anyway).

Glad I got that before the 0.8 release, phew.

* Fix bug in reschedule_wakeup

* Fix adjust_wakeup

examples/game_of_life.rs

@@ -6,11 +6,15 @@ use mini_gl_fb::glutin::event::{VirtualKeyCode, MouseButton};
 use mini_gl_fb::glutin::event_loop::EventLoop;
 use mini_gl_fb::glutin::dpi::LogicalSize;
 
-use std::time::SystemTime;
+use std::time::{Instant, Duration};
+use mini_gl_fb::breakout::Wakeup;
 
 const WIDTH: usize = 200;
 const HEIGHT: usize = 200;
 
+const NORMAL_SPEED: u64 = 500;
+const TURBO_SPEED: u64 = 20;
+
 fn main() {
     let mut event_loop = EventLoop::new();
     let mut fb = mini_gl_fb::get_fancy(config! {
@@ -35,38 +39,62 @@ fn main() {
     cells[52 * WIDTH + 50] = true;
     cells[52 * WIDTH + 51] = true;
 
-    let mut previous = SystemTime::now();
+    // ID of the Wakeup which means we should update the board
-    let mut extra_delay: f64 = 0.0;
+    let mut update_id: Option<u32> = None;
 
     fb.glutin_handle_basic_input(&mut event_loop, |fb, input| {
-        let elapsed = previous.elapsed().unwrap();
+        // We're going to use wakeups to update the grid
-        let seconds = elapsed.as_secs() as f64 + elapsed.subsec_nanos() as f64 * 1e-9;
+        input.wait = true;
+
+        if update_id.is_none() {
+            update_id = Some(input.schedule_wakeup(Instant::now() + Duration::from_millis(500)))
+        } else if let Some(mut wakeup) = input.wakeup {
+            if Some(wakeup.id) == update_id {
+                // Time to update our grid
+                calculate_neighbors(&mut cells, &mut neighbors);
+                make_some_babies(&mut cells, &mut neighbors);
+                fb.update_buffer(&cells);
+
+                // Reschedule another update
+                wakeup.when = Instant::now() + Duration::from_millis(
+                    if input.key_is_down(VirtualKeyCode::LShift) {
+                        TURBO_SPEED
+                    } else {
+                        NORMAL_SPEED
+                    }
+                );
+
+                input.reschedule_wakeup(wakeup);
+            }
+
+            // We will get called again after all wakeups are handled
+            return true;
+        }
 
         if input.key_is_down(VirtualKeyCode::Escape) {
             return false;
         }
 
-        if input.mouse_is_down(MouseButton::Left) {
+        if input.mouse_is_down(MouseButton::Left) || input.mouse_is_down(MouseButton::Right) {
             // Mouse was pressed
             let (x, y) = input.mouse_pos;
             let x = x.min(WIDTH as f64 - 0.0001).max(0.0).floor() as usize;
             let y = y.min(HEIGHT as f64 - 0.0001).max(0.0).floor() as usize;
-            cells[y * WIDTH + x] = true;
+            cells[y * WIDTH + x] = input.mouse_is_down(MouseButton::Left);
             fb.update_buffer(&cells);
             // Give the user extra time to make something pretty each time they click
-            previous = SystemTime::now();
+            if !input.key_is_down(VirtualKeyCode::LShift) {
-            extra_delay = (extra_delay + 0.5).min(2.0);
+                input.adjust_wakeup(update_id.unwrap(), Wakeup::after_millis(2000));
+            }
         }
 
-        // Each generation should stay on screen for half a second
+        // TODO support right shift. Probably by querying modifiers somehow. (modifiers support)
-        if seconds > 0.5 + extra_delay {
+        if input.key_pressed(VirtualKeyCode::LShift) {
-            previous = SystemTime::now();
+            // immediately update
-            calculate_neighbors(&mut cells, &mut neighbors);
+            input.adjust_wakeup(update_id.unwrap(), Wakeup::after_millis(0));
-            make_some_babies(&mut cells, &mut neighbors);
+        } else if input.key_released(VirtualKeyCode::LShift) {
-            fb.update_buffer(&cells);
+            // immediately stop updating
-            extra_delay = 0.0;
+            input.adjust_wakeup(update_id.unwrap(), Wakeup::after_millis(NORMAL_SPEED));
-        } else if input.resized {
-            fb.redraw();
         }
 
         true

src/breakout.rs

@@ -6,6 +6,7 @@ use core::Framebuffer;
 
 use std::collections::HashMap;
 use glutin::event::{MouseButton, VirtualKeyCode, ModifiersState};
+use std::time::{Instant, Duration};
 
 /// `GlutinBreakout` is useful when you are growing out of the basic input methods and synchronous
 /// nature of [`MiniGlFb`][crate::MiniGlFb], since it's more powerful than the the higher-level
@@ -215,6 +216,37 @@ impl GlutinBreakout {
     }
 }
 
+#[non_exhaustive]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub struct Wakeup {
+    /// The [`Instant`] at which this wakeup is scheduled to happen. If the [`Instant`] is in the
+    /// past, the wakeup will happen instantly.
+    pub when: Instant,
+
+    /// A numeric identifier that can be used to determine which wakeup your callback is being run
+    /// for.
+    pub id: u32,
+}
+
+impl Wakeup {
+    /// Returns [`Instant::now`]`() + duration`.
+    pub fn after(duration: Duration) -> Instant {
+        Instant::now() + duration
+    }
+
+    /// The same as [`Wakeup::after`], but constructs a [`Duration`] from a number of milliseconds,
+    /// since [`Duration`] methods are so long...
+    pub fn after_millis(millis: u64) -> Instant {
+        Self::after(Duration::from_millis(millis))
+    }
+
+    /// Modifies this wakeup to trigger after `duration` has passed from [`Instant::now`],
+    /// calculated via [`Wakeup::after`].
+    pub fn trigger_after(&mut self, duration: Duration) {
+        self.when = Self::after(duration);
+    }
+}
+
 /// Used for [`MiniGlFb::glutin_handle_basic_input`][crate::MiniGlFb::glutin_handle_basic_input].
 /// Contains the current state of the window in a polling-like fashion.
 #[non_exhaustive]
@@ -245,6 +277,24 @@ pub struct BasicInput {
     /// If this is set to `true` by your callback, it will not be called as fast as possible, but
     /// rather only when the input changes.
     pub wait: bool,
+    /// A record of all the [`Wakeup`]s that are scheduled to happen. If your callback is being
+    /// called because of a wakeup, [`BasicInput::wakeup`] will be set to `Some(id)` where `id` is
+    /// the unique identifier of the [`Wakeup`].
+    ///
+    /// Wakeups can be scheduled using [`BasicInput::schedule_wakeup`]. Wakeups can be cancelled
+    /// using [`BasicInput::cancel_wakeup`], or by removing the item from the [`Vec`].
+    // NOTE: THIS VEC IS SUPPOSED TO ALWAYS BE SORTED BY SOONEST WAKEUP FIRST!
+    // This contract MUST be upheld at all times, or else weird behavior will result. Only the
+    // wakeup at index 0 is ever checked at a time, no other wakeups will be queued if it is not due
+    // yet. DO NOT IGNORE THIS WARNING!
+    pub wakeups: Vec<Wakeup>,
+    /// Indicates to your callback which [`Wakeup`] it should be handling. Normally, it's okay to
+    /// ignore this, as it will always be [`None`] unless you manually schedule wakeups using
+    /// [`BasicInput::schedule_wakeup`].
+    pub wakeup: Option<Wakeup>,
+    // Internal variable used to keep track of what the next wakeup ID should be. Doesn't need to be
+    // `pub`; `BasicInput` is already `#[non_exhaustive]`.
+    _next_wakeup_id: u32,
 }
 
 impl BasicInput {
@@ -287,4 +337,41 @@ impl BasicInput {
     pub fn key_released(&self, button: VirtualKeyCode) -> bool {
         &(true, false) == self.keys.get(&button).unwrap_or(&(false, false))
     }
+
+    /// Given an [`Instant`] in the future (or in the past, in which case it will be triggered
+    /// immediately), schedules a wakeup to be triggered then. Returns the ID of the wakeup, which
+    /// will be the ID of [`BasicInput::wakeup`] if your callback is getting called by the wakeup.
+    pub fn schedule_wakeup(&mut self, when: Instant) -> u32 {
+        let wakeup = Wakeup { when, id: self._next_wakeup_id };
+        self._next_wakeup_id += 1;
+        self.reschedule_wakeup(wakeup);
+        wakeup.id
+    }
+
+    /// Reschedules a wakeup. It is perfectly valid to re-use IDs of wakeups that have already been
+    /// triggered; that is why [`BasicInput::wakeup`] is a [`Wakeup`] and not just a [`u32`].
+    pub fn reschedule_wakeup(&mut self, wakeup: Wakeup) {
+        let at = self.wakeups.iter().position(|o| o.when > wakeup.when).unwrap_or(self.wakeups.len());
+        self.wakeups.insert(at, wakeup);
+    }
+
+    /// Cancels a previously scheduled [`Wakeup`] by its ID. Returns the [`Wakeup`] if it is found,
+    /// otherwise returns [`None`].
+    pub fn cancel_wakeup(&mut self, id: u32) -> Option<Wakeup> {
+        Some(self.wakeups.remove(self.wakeups.iter().position(|w| w.id == id)?))
+    }
+
+    /// Changing the time of an upcoming wakeup is common enough that there's a utility method to do
+    /// it for you. Given an ID and an [`Instant`], finds the [`Wakeup`] with the given ID and sets
+    /// its time to `when`. Returns `true` if a wakeup was found, `false` otherwise.
+    pub fn adjust_wakeup(&mut self, id: u32, when: Instant) -> bool {
+        if let Some(mut wakeup) = self.cancel_wakeup(id) {
+            // Put it back in the queue; this is important because it might end up somewhere else
+            wakeup.when = when;
+            self.reschedule_wakeup(wakeup);
+            true
+        } else {
+            false
+        }
+    }
 }

src/core.rs

@@ -12,7 +12,8 @@ use std::mem::size_of_val;
 use glutin::window::WindowBuilder;
 use glutin::event_loop::{EventLoop, ControlFlow};
 use glutin::platform::run_return::EventLoopExtRunReturn;
-use glutin::event::{Event, WindowEvent, VirtualKeyCode, ElementState, KeyboardInput};
+use glutin::event::{Event, WindowEvent, VirtualKeyCode, ElementState, KeyboardInput, StartCause};
+use std::time::Instant;
 
 /// Create a context using glutin given a configuration.
 pub fn init_glutin_context<S: ToString, ET: 'static>(
@@ -215,7 +216,7 @@ impl Internal {
         });
     }
 
-    pub fn glutin_handle_basic_input<ET: 'static, F: FnMut(&mut Framebuffer, &BasicInput) -> bool>(
+    pub fn glutin_handle_basic_input<ET: 'static, F: FnMut(&mut Framebuffer, &mut BasicInput) -> bool>(
         &mut self, event_loop: &mut EventLoop<ET>, mut handler: F
     ) {
         let mut previous_input: Option<BasicInput> = None;
@@ -234,9 +235,12 @@ impl Internal {
                 val.0 = val.1;
             }
 
-            match event {
+            match &event {
                 Event::WindowEvent { event, .. } => match event {
-                    WindowEvent::CloseRequested => *flow = ControlFlow::Exit,
+                    WindowEvent::CloseRequested => {
+                        *flow = ControlFlow::Exit;
+                        return;
+                    },
                     WindowEvent::KeyboardInput {
                         input: KeyboardInput {
                             virtual_keycode: Some(vk),
@@ -245,23 +249,23 @@ impl Internal {
                         },
                         ..
                     } => {
-                        let key = input.keys.entry(vk)
+                        let key = input.keys.entry(*vk)
                             .or_insert((false, false));
-                        key.1 = state == ElementState::Pressed;
+                        key.1 = *state == ElementState::Pressed;
                     }
                     WindowEvent::CursorMoved { position, .. } => {
-                        new_mouse_pos = Some(position);
+                        new_mouse_pos = Some(*position);
                     }
                     WindowEvent::MouseInput { state, button, .. } => {
-                        let button = input.mouse.entry(button)
+                        let button = input.mouse.entry(*button)
                             .or_insert((false, false));
-                        button.1 = state == ElementState::Pressed;
+                        button.1 = *state == ElementState::Pressed;
                     }
                     WindowEvent::ModifiersChanged(modifiers) => {
-                        input.modifiers = modifiers;
+                        input.modifiers = *modifiers;
                     }
                     WindowEvent::Resized(logical_size) => {
-                        new_size = Some(logical_size);
+                        new_size = Some(*logical_size);
                     }
                     _ => {}
                 },
@@ -270,7 +274,7 @@ impl Internal {
 
             if let Some(size) = new_size {
                 self.resize_viewport(size.width, size.height);
-                input.resized = false;
+                input.resized = true;
             }
 
             if let Some(pos) = new_mouse_pos {
@@ -289,18 +293,40 @@ impl Internal {
                 input.mouse_pos = mouse_pos;
             }
 
+            while let Some(wakeup) = input.wakeups.get(0) {
+                if wakeup.when > Instant::now() { break; }
+
+                input.wakeup = Some(*wakeup);
+                input.wakeups.remove(0);
+
+                if !handler(&mut self.fb, &mut input) {
+                    *flow = ControlFlow::Exit;
+                    return;
+                }
+            }
+
+            input.wakeup = None;
+
             if input.wait {
-                *flow = ControlFlow::Wait;
+                if let Some(wakeup) = input.wakeups.get(0) {
+                    *flow = ControlFlow::WaitUntil(wakeup.when)
+                } else {
+                    *flow = ControlFlow::Wait;
+                }
 
                 // handler only wants to be notified when the input changes
                 if previous_input.as_ref().map_or(true, |p| *p != input) {
-                    if !handler(&mut self.fb, &input) {
+                    // wakeups have already been handled
-                        *flow = ControlFlow::Exit;
+                    if let Event::NewEvents(StartCause::ResumeTimeReached { .. }) = &event {
+                    } else {
+                        if !handler(&mut self.fb, &mut input) {
+                            *flow = ControlFlow::Exit;
+                        }
                     }
                 }
             } else {
                 // handler wants to be notified regardless
-                if !handler(&mut self.fb, &input) {
+                if !handler(&mut self.fb, &mut input) {
                     *flow = ControlFlow::Exit;
                 } else {
                     *flow = ControlFlow::Poll;

src/lib.rs

@@ -352,7 +352,7 @@ impl MiniGlFb {
     /// You can cause the handler to exit by returning false from it. This does not kill the
     /// window, so as long as you still have it in scope, you can actually keep using it and,
     /// for example, resume handling input but with a different handler callback.
-    pub fn glutin_handle_basic_input<ET: 'static, F: FnMut(&mut Framebuffer, &BasicInput) -> bool>(
+    pub fn glutin_handle_basic_input<ET: 'static, F: FnMut(&mut Framebuffer, &mut BasicInput) -> bool>(
         &mut self, event_loop: &mut EventLoop<ET>, handler: F
     ) {
         self.internal.glutin_handle_basic_input(event_loop, handler);