From 387567a917e1944a3848ee7d21c14013a1a4f55d Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Thu, 4 Nov 2021 19:37:02 +0100
Subject: [PATCH] macOS: Fix native file dialogs freezing the event loop
 (#2027)

* macOS: Ignore all events while in the callback

Previously all native dialogs, such as [rfd](https://github.com/PolyMeilex/rfd), would cause the event loop (event_loop.run) to freeze.

* Update changelog

* spelling

* Fix merge mistake

* Add link to issue in the code

Co-authored-by: Poly <marynczak.bartlomiej@gmail.com>
---
 CHANGELOG.md                         |  1 +
 src/platform_impl/macos/app_state.rs | 35 +++++++++++++++-------------
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 59920a2bb8..e6d5f776de 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@
 - On Wayland, add an enabled-by-default feature called `wayland-dlopen` so users can opt out of using `dlopen` to load system libraries.
 - **Breaking:** On Android, bump `ndk` and `ndk-glue` to 0.4.
 - On Windows, increase wait timer resolution for more accurate timing when using `WaitUntil`.
+- On macOS, fix native file dialogs hanging the event loop.
 
 # 0.25.0 (2021-05-15)
 
diff --git a/src/platform_impl/macos/app_state.rs b/src/platform_impl/macos/app_state.rs
index 5f1483339f..0824354b51 100644
--- a/src/platform_impl/macos/app_state.rs
+++ b/src/platform_impl/macos/app_state.rs
@@ -307,7 +307,9 @@ impl AppState {
         let panic_info = panic_info
             .upgrade()
             .expect("The panic info must exist here. This failure indicates a developer error.");
-        if panic_info.is_panicking() || !HANDLER.is_ready() {
+
+        // Return when in callback due to https://github.com/rust-windowing/winit/issues/1779
+        if panic_info.is_panicking() || !HANDLER.is_ready() || HANDLER.get_in_callback() {
             return;
         }
         let start = HANDLER.get_start_time().unwrap();
@@ -371,24 +373,25 @@ impl AppState {
         let panic_info = panic_info
             .upgrade()
             .expect("The panic info must exist here. This failure indicates a developer error.");
-        if panic_info.is_panicking() || !HANDLER.is_ready() {
+
+        // Return when in callback due to https://github.com/rust-windowing/winit/issues/1779
+        if panic_info.is_panicking() || !HANDLER.is_ready() || HANDLER.get_in_callback() {
             return;
         }
-        if !HANDLER.get_in_callback() {
-            HANDLER.set_in_callback(true);
-            HANDLER.handle_user_events();
-            for event in HANDLER.take_events() {
-                HANDLER.handle_nonuser_event(event);
-            }
-            HANDLER.handle_nonuser_event(EventWrapper::StaticEvent(Event::MainEventsCleared));
-            for window_id in HANDLER.should_redraw() {
-                HANDLER.handle_nonuser_event(EventWrapper::StaticEvent(Event::RedrawRequested(
-                    window_id,
-                )));
-            }
-            HANDLER.handle_nonuser_event(EventWrapper::StaticEvent(Event::RedrawEventsCleared));
-            HANDLER.set_in_callback(false);
+
+        HANDLER.set_in_callback(true);
+        HANDLER.handle_user_events();
+        for event in HANDLER.take_events() {
+            HANDLER.handle_nonuser_event(event);
+        }
+        HANDLER.handle_nonuser_event(EventWrapper::StaticEvent(Event::MainEventsCleared));
+        for window_id in HANDLER.should_redraw() {
+            HANDLER
+                .handle_nonuser_event(EventWrapper::StaticEvent(Event::RedrawRequested(window_id)));
         }
+        HANDLER.handle_nonuser_event(EventWrapper::StaticEvent(Event::RedrawEventsCleared));
+        HANDLER.set_in_callback(false);
+
         if HANDLER.should_exit() {
             unsafe {
                 let app: id = NSApp();