Fix iOS support in eframe (#3241)

* Fix the app only taking up half the screen size on iPad

* Fix request_repaint not working on iOS

* Always use run_and_exit on iOS since run_and_return is not supported by winit on iOS right now.

* Fix typo

* Fix eframe glow on ios

* Handle more cases

Author: lucasmerlin

crates/eframe/src/native/epi_integration.rs

@@ -138,6 +138,9 @@ pub fn window_builder<E>(
 
     window_builder = window_builder_drag_and_drop(window_builder, *drag_and_drop_support);
 
+    // Always use the default window size / position on iOS. Trying to restore the previous position
+    // causes the window to be shown too small.
+    #[cfg(not(target_os = "ios"))]
     let inner_size_points = if let Some(mut window_settings) = window_settings {
         // Restore pos/size from previous session
 
@@ -163,6 +166,7 @@ pub fn window_builder<E>(
         *initial_window_size
     };
 
+    #[cfg(not(target_os = "ios"))]
     if *centered {
         if let Some(monitor) = event_loop.available_monitors().next() {
             let monitor_size = monitor.size().to_logical::<f64>(monitor.scale_factor());

crates/eframe/src/native/run.rs

@@ -119,6 +119,7 @@ fn with_event_loop<R>(
     })
 }
 
+#[cfg(not(target_os = "ios"))]
 fn run_and_return(
     event_loop: &mut EventLoop<UserEvent>,
     mut winit_app: impl WinitApp,
@@ -332,6 +333,11 @@ fn run_and_exit(event_loop: EventLoop<UserEvent>, mut winit_app: impl WinitApp +
             next_repaint_time = extremely_far_future();
             ControlFlow::Poll
         } else {
+            // WaitUntil seems to not work on iOS
+            #[cfg(target_os = "ios")]
+            if let Some(window) = winit_app.window() {
+                window.request_redraw();
+            }
             ControlFlow::WaitUntil(next_repaint_time)
         };
     })
@@ -1052,6 +1058,7 @@ mod glow_integration {
         mut native_options: epi::NativeOptions,
         app_creator: epi::AppCreator,
     ) -> Result<()> {
+        #[cfg(not(target_os = "ios"))]
         if native_options.run_and_return {
             with_event_loop(native_options, |event_loop, native_options| {
                 let glow_eframe =
@@ -1063,6 +1070,13 @@ mod glow_integration {
             let glow_eframe = GlowWinitApp::new(&event_loop, app_name, native_options, app_creator);
             run_and_exit(event_loop, glow_eframe);
         }
+
+        #[cfg(target_os = "ios")]
+        {
+            let event_loop = create_event_loop_builder(&mut native_options).build();
+            let glow_eframe = GlowWinitApp::new(&event_loop, app_name, native_options, app_creator);
+            run_and_exit(event_loop, glow_eframe);
+        }
     }
 }
 
@@ -1490,6 +1504,7 @@ mod wgpu_integration {
         mut native_options: epi::NativeOptions,
         app_creator: epi::AppCreator,
     ) -> Result<()> {
+        #[cfg(not(target_os = "ios"))]
         if native_options.run_and_return {
             with_event_loop(native_options, |event_loop, native_options| {
                 let wgpu_eframe =
@@ -1501,6 +1516,13 @@ mod wgpu_integration {
             let wgpu_eframe = WgpuWinitApp::new(&event_loop, app_name, native_options, app_creator);
             run_and_exit(event_loop, wgpu_eframe);
         }
+
+        #[cfg(target_os = "ios")]
+        {
+            let event_loop = create_event_loop_builder(&mut native_options).build();
+            let wgpu_eframe = WgpuWinitApp::new(&event_loop, app_name, native_options, app_creator);
+            run_and_exit(event_loop, wgpu_eframe);
+        }
     }
 }