Remove resize block on Windows (#634)

* Remove Windows block on resize

* Add CHANGELOG entry

* Move CHANGELOG entry to Unreleased

* Further edits to CHANGELOG entry

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 
-- Fixed graphical glitches when resizing on Wayland
+- Fixed graphical glitches when resizing on Wayland.
+- On Windows, fix freezes when performing certain actions after a window resize has been triggered. Reintroduces some visual artifacts when resizing.
 
 # Version 0.17.2 (2018-08-19)
 

src/platform/windows/events_loop.rs

@@ -18,7 +18,7 @@ use std::collections::HashMap;
 use std::ffi::OsString;
 use std::os::windows::ffi::OsStringExt;
 use std::os::windows::io::AsRawHandle;
-use std::sync::{Arc, Barrier, Condvar, mpsc, Mutex};
+use std::sync::{Arc, Barrier, mpsc, Mutex};
 
 use winapi::ctypes::c_int;
 use winapi::shared::minwindef::{
@@ -138,10 +138,6 @@ pub struct EventsLoop {
     thread_id: DWORD,
     // Receiver for the events. The sender is in the background thread.
     receiver: mpsc::Receiver<Event>,
-    // Variable that contains the block state of the win32 event loop thread during a WM_SIZE event.
-    // The mutex's value is `true` when it's blocked, and should be set to false when it's done
-    // blocking. That's done by the parent thread when it receives a Resized event.
-    win32_block_loop: Arc<(Mutex<bool>, Condvar)>,
 }
 
 impl EventsLoop {
@@ -154,8 +150,6 @@ impl EventsLoop {
 
         // The main events transfer channel.
         let (tx, rx) = mpsc::channel();
-        let win32_block_loop = Arc::new((Mutex::new(false), Condvar::new()));
-        let win32_block_loop_child = win32_block_loop.clone();
 
         // Local barrier in order to block the `new()` function until the background thread has
         // an events queue.
@@ -167,7 +161,6 @@ impl EventsLoop {
                 *context_stash.borrow_mut() = Some(ThreadLocalData {
                     sender: tx,
                     windows: HashMap::with_capacity(4),
-                    win32_block_loop: win32_block_loop_child,
                     mouse_buttons_down: 0
                 });
             });
@@ -220,7 +213,6 @@ impl EventsLoop {
         EventsLoop {
             thread_id,
             receiver: rx,
-            win32_block_loop,
         }
     }
 
@@ -232,18 +224,8 @@ impl EventsLoop {
                 Ok(e) => e,
                 Err(_) => return
             };
-            let is_resize = match event {
-                Event::WindowEvent{ event: WindowEvent::Resized(..), .. } => true,
-                _ => false
-            };
 
             callback(event);
-            if is_resize {
-                let (ref mutex, ref cvar) = *self.win32_block_loop;
-                let mut block_thread = mutex.lock().unwrap();
-                *block_thread = false;
-                cvar.notify_all();
-            }
         }
     }
 
@@ -255,18 +237,8 @@ impl EventsLoop {
                 Ok(e) => e,
                 Err(_) => return
             };
-            let is_resize = match event {
-                Event::WindowEvent{ event: WindowEvent::Resized(..), .. } => true,
-                _ => false
-            };
 
             let flow = callback(event);
-            if is_resize {
-                let (ref mutex, ref cvar) = *self.win32_block_loop;
-                let mut block_thread = mutex.lock().unwrap();
-                *block_thread = false;
-                cvar.notify_all();
-            }
             match flow {
                 ControlFlow::Continue => continue,
                 ControlFlow::Break => break,
@@ -399,7 +371,6 @@ thread_local!(static CONTEXT_STASH: RefCell<Option<ThreadLocalData>> = RefCell::
 struct ThreadLocalData {
     sender: mpsc::Sender<Event>,
     windows: HashMap<HWND, Arc<Mutex<WindowState>>>,
-    win32_block_loop: Arc<(Mutex<bool>, Condvar)>,
     mouse_buttons_down: u32
 }
 
@@ -527,24 +498,7 @@ pub unsafe extern "system" fn callback(
                     event: Resized(logical_size),
                 };
 
-                // If this window has been inserted into the window map, the resize event happened
-                // during the event loop. If it hasn't, the event happened on window creation and
-                // should be ignored.
-                if cstash.windows.get(&window).is_some() {
-                    let (ref mutex, ref cvar) = *cstash.win32_block_loop;
-                    let mut block_thread = mutex.lock().unwrap();
-                    *block_thread = true;
-
-                    // The event needs to be sent after the lock to ensure that `notify_all` is
-                    // called after `wait`.
-                    cstash.sender.send(event).ok();
-
-                    while *block_thread {
-                        block_thread = cvar.wait(block_thread).unwrap();
-                    }
-                } else {
-                    cstash.sender.send(event).ok();
-                }
+                cstash.sender.send(event).ok();
             });
             0
         },