Immediate Viewport in normal operation

crates/eframe/src/native/glow_integration.rs

@@ -480,7 +480,7 @@ impl GlowWinitRunning {
     ) -> EventResult {
         crate::profile_function!();
 
-        let Some(viewport_id) = self
+        let Some(mut viewport_id) = self
             .glutin
             .borrow()
             .viewport_from_window
@@ -496,24 +496,37 @@ impl GlowWinitRunning {
         let mut frame_timer = crate::stopwatch::Stopwatch::new();
         frame_timer.start();
 
-        {
-            let glutin = self.glutin.borrow();
+        let (raw_input, viewport_ui_cb) = {
+            crate::profile_scope!("Prepare");
+            let mut glutin = self.glutin.borrow_mut();
             let viewport = &glutin.viewports[&viewport_id];
+
+            let mut is_change_to_root = false;
             let is_immediate = viewport.viewport_ui_cb.is_none();
+
             if is_immediate && viewport_id != ViewportId::ROOT {
-                // This will only happen if this is an immediate viewport.
-                // That means that the viewport cannot be rendered by itself and needs his parent to be rendered.
+                is_change_to_root = true;
+
                 if let Some(parent_viewport) = glutin.viewports.get(&viewport.ids.parent) {
-                    if let Some(window) = parent_viewport.window.as_ref() {
-                        return EventResult::RepaintNext(window.id());
+                    let is_differed_parent = parent_viewport.viewport_ui_cb.is_some();
+                    if is_differed_parent {
+                        is_change_to_root = false;
+                        viewport_id = parent_viewport.ids.this;
                     }
                 }
-                return EventResult::Wait;
             }
-        }
 
-        let (raw_input, viewport_ui_cb) = {
-            let mut glutin = self.glutin.borrow_mut();
+            if is_change_to_root {
+                // This will only happen if this is an immediate viewport.
+                // That means that the viewport cannot be rendered by itself and needs his parent to be rendered.
+                if let Some(root_viewport) = glutin.viewports.get(&ViewportId::ROOT) {
+                    viewport_id = root_viewport.ids.this;
+                } else {
+                    // Not actually used. Because there is always a `Some()` value.
+                    return EventResult::Wait;
+                }
+            }
+
             let egui_ctx = glutin.egui_ctx.clone();
             let viewport = glutin.viewports.get_mut(&viewport_id).unwrap();
             let Some(window) = viewport.window.as_ref() else {
@@ -715,7 +728,6 @@ impl GlowWinitRunning {
         // to resizes anyway, as doing so avoids dropping frames.
         //
         // See: https://github.com/emilk/egui/issues/903
-        let mut repaint_asap = false;
 
         match event {
             winit::event::WindowEvent::Focused(new_focused) => {
@@ -728,7 +740,6 @@ impl GlowWinitRunning {
                 // This solves an issue where the app would panic when minimizing on Windows.
                 if 0 < physical_size.width && 0 < physical_size.height {
                     if let Some(viewport_id) = viewport_id {
-                        repaint_asap = true;
                         glutin.resize(viewport_id, *physical_size);
                     }
                 }
@@ -786,11 +797,7 @@ impl GlowWinitRunning {
         }
 
         if event_response.repaint {
-            if repaint_asap {
-                EventResult::RepaintNow(window_id)
-            } else {
-                EventResult::RepaintNext(window_id)
-            }
+            EventResult::RepaintNow(window_id)
         } else {
             EventResult::Wait
         }

crates/eframe/src/native/wgpu_integration.rs

@@ -509,7 +509,7 @@ impl WgpuWinitRunning {
     fn run_ui_and_paint(&mut self, window_id: WindowId) -> EventResult {
         crate::profile_function!();
 
-        let Some(viewport_id) = self
+        let Some(mut viewport_id) = self
             .shared
             .borrow()
             .viewport_from_window
@@ -539,19 +539,32 @@ impl WgpuWinitRunning {
                 viewports, painter, ..
             } = &mut *shared_lock;
 
-            if viewport_id != ViewportId::ROOT {
-                let Some(viewport) = viewports.get(&viewport_id) else {
-                    return EventResult::Wait;
-                };
+            let Some(viewport) = viewports.get(&viewport_id) else {
+                return EventResult::Wait;
+            };
 
-                if viewport.viewport_ui_cb.is_none() {
-                    // This will only happen if this is an immediate viewport.
-                    // That means that the viewport cannot be rendered by itself and needs his parent to be rendered.
-                    if let Some(viewport) = viewports.get(&viewport.ids.parent) {
-                        if let Some(window) = viewport.window.as_ref() {
-                            return EventResult::RepaintNext(window.id());
-                        }
+            let mut is_change_to_root = false;
+            let is_immediate = viewport.viewport_ui_cb.is_none();
+
+            if is_immediate && viewport_id != ViewportId::ROOT {
+                is_change_to_root = true;
+
+                if let Some(parent_viewport) = viewports.get(&viewport.ids.parent) {
+                    let is_differed_parent = parent_viewport.viewport_ui_cb.is_some();
+                    if is_differed_parent {
+                        is_change_to_root = false;
+                        viewport_id = parent_viewport.ids.this;
                     }
+                }
+            }
+
+            if is_change_to_root {
+                // This will only happen if this is an immediate viewport.
+                // That means that the viewport cannot be rendered by itself and needs his parent to be rendered.
+                if let Some(root_viewport) = viewports.get(&ViewportId::ROOT) {
+                    viewport_id = root_viewport.ids.this;
+                } else {
+                    // Not actually used. Because there is always a `Some()` value.
                     return EventResult::Wait;
                 }
             }
@@ -732,7 +745,6 @@ impl WgpuWinitRunning {
         // to resizes anyway, as doing so avoids dropping frames.
         //
         // See: https://github.com/emilk/egui/issues/903
-        let mut repaint_asap = false;
 
         match event {
             winit::event::WindowEvent::Focused(new_focused) => {
@@ -749,7 +761,6 @@ impl WgpuWinitRunning {
                         NonZeroU32::new(physical_size.width),
                         NonZeroU32::new(physical_size.height),
                     ) {
-                        repaint_asap = true;
                         shared.painter.on_window_resized(viewport_id, width, height);
                     }
                 }
@@ -797,11 +808,7 @@ impl WgpuWinitRunning {
         if integration.should_close() {
             EventResult::Exit
         } else if event_response.repaint {
-            if repaint_asap {
-                EventResult::RepaintNow(window_id)
-            } else {
-                EventResult::RepaintNext(window_id)
-            }
+            EventResult::RepaintNow(window_id)
         } else {
             EventResult::Wait
         }