Move the viewport commands into the per-viewport output

crates/eframe/src/native/run.rs

@@ -564,7 +564,6 @@ mod glow_integration {
                 shapes,
                 pixels_per_point,
                 viewports: viewports_out,
-                viewport_commands,
             } = full_output;
 
             let GlutinWindowContext {
@@ -649,19 +648,6 @@ mod glow_integration {
 
             glutin.process_viewport_updates(viewports_out, focused_viewport);
 
-            for (viewport_id, command) in viewport_commands {
-                if let Some(viewport) = glutin.viewports.get(&viewport_id) {
-                    if let Some(window) = &viewport.window {
-                        let is_viewport_focused = focused_viewport == Some(viewport_id);
-                        egui_winit::process_viewport_commands(
-                            [command],
-                            window,
-                            is_viewport_focused,
-                        );
-                    }
-                }
-            }
-
             if integration.should_close() {
                 EventResult::Exit
             } else {
@@ -1169,21 +1155,25 @@ mod glow_integration {
 
         fn process_viewport_updates(
             &mut self,
-            viewport_output: Vec<ViewportOutput>,
+            viewport_output: ViewportIdMap<ViewportOutput>,
             focused_viewport: Option<ViewportId>,
         ) {
             crate::profile_function!();
 
             let mut active_viewports_ids = ViewportIdSet::default();
             active_viewports_ids.insert(ViewportId::ROOT);
 
-            for ViewportOutput {
-                ids,
-                builder,
-                viewport_ui_cb,
-            } in viewport_output
+            for (
+                viewport_id,
+                ViewportOutput {
+                    ids,
+                    builder,
+                    viewport_ui_cb,
+                    commands,
+                },
+            ) in viewport_output
             {
-                active_viewports_ids.insert(ids.this);
+                active_viewports_ids.insert(viewport_id);
 
                 initialize_or_update_viewport(
                     &mut self.viewports,
@@ -1192,6 +1182,17 @@ mod glow_integration {
                     viewport_ui_cb,
                     focused_viewport,
                 );
+
+                if let Some(viewport) = self.viewports.get(&viewport_id) {
+                    if let Some(window) = &viewport.window {
+                        let is_viewport_focused = focused_viewport == Some(viewport_id);
+                        egui_winit::process_viewport_commands(
+                            commands,
+                            window,
+                            is_viewport_focused,
+                        );
+                    }
+                }
             }
 
             // GC old viewports
@@ -2455,10 +2456,7 @@ mod wgpu_integration {
 
                 let raw_input = egui_winit.as_mut().unwrap().take_egui_input(
                     window,
-                    ViewportIdPair {
-                        this: viewport_id,
-                        parent: ids.parent,
-                    },
+                    ViewportIdPair::from_self_and_parent(viewport_id, ids.parent),
                 );
 
                 integration.pre_update(window);
@@ -2504,7 +2502,6 @@ mod wgpu_integration {
                 shapes,
                 pixels_per_point,
                 viewports: out_viewports,
-                viewport_commands,
             } = full_output;
 
             integration.handle_platform_output(window, viewport_id, platform_output, egui_winit);
@@ -2532,13 +2529,17 @@ mod wgpu_integration {
             active_viewports_ids.insert(ViewportId::ROOT);
 
             // Add new viewports, and update existing ones:
-            for ViewportOutput {
-                ids,
-                builder,
-                viewport_ui_cb,
-            } in out_viewports
+            for (
+                viewport_id,
+                ViewportOutput {
+                    ids,
+                    builder,
+                    viewport_ui_cb,
+                    commands,
+                },
+            ) in out_viewports
             {
-                active_viewports_ids.insert(ids.this);
+                active_viewports_ids.insert(viewport_id);
 
                 initialize_or_update_viewport(
                     viewports,
@@ -2547,16 +2548,13 @@ mod wgpu_integration {
                     viewport_ui_cb,
                     focused_viewport,
                 );
-            }
 
-            // Handle viewport commands:
-            for (viewport_id, command) in viewport_commands {
                 if let Some(window) = viewports
                     .get(&viewport_id)
                     .and_then(|vp| vp.window.as_ref())
                 {
                     let is_viewport_focused = focused_viewport == Some(viewport_id);
-                    egui_winit::process_viewport_commands([command], window, is_viewport_focused);
+                    egui_winit::process_viewport_commands(commands, window, is_viewport_focused);
                 }
             }
 

crates/egui/src/context.rs

@@ -146,6 +146,7 @@ struct ViewportState {
     // The output of a frame:
     graphics: GraphicLayers,
     output: PlatformOutput,
+    commands: Vec<ViewportCommand>,
 }
 
 /// Per-viewport state related to repaint scheduling.
@@ -185,7 +186,6 @@ struct ContextImpl {
 
     viewport_parents: ViewportIdMap<ViewportId>,
     viewports: ViewportIdMap<ViewportState>,
-    viewport_commands: Vec<(ViewportId, ViewportCommand)>,
 
     embed_viewports: bool,
 
@@ -1563,24 +1563,36 @@ impl ContextImpl {
             true
         });
 
+        // This is used to resume the last frame!
+        self.viewport_stack.pop();
+
+        // The last viewport is not necessarily the root viewport,
+        // just the top _immediate_ viewport.
+        let is_last = self.viewport_stack.is_empty();
+
         let out_viewports = self
             .viewports
-            .iter()
+            .iter_mut()
             .map(|(&id, viewport)| {
                 let parent = *self.viewport_parents.entry(id).or_default();
-                ViewportOutput {
-                    ids: ViewportIdPair { this: id, parent },
-                    builder: viewport.builder.clone(),
-                    viewport_ui_cb: viewport.viewport_ui_cb.clone(),
-                }
+                let commands = if is_last {
+                    std::mem::take(&mut viewport.commands)
+                } else {
+                    vec![]
+                };
+
+                (
+                    id,
+                    ViewportOutput {
+                        ids: ViewportIdPair::from_self_and_parent(id, parent),
+                        builder: viewport.builder.clone(),
+                        viewport_ui_cb: viewport.viewport_ui_cb.clone(),
+                        commands,
+                    },
+                )
             })
             .collect();
 
-        // This is used to resume the last frame!
-        self.viewport_stack.pop();
-
-        let is_last = self.viewport_stack.is_empty();
-
         if is_last {
             // Remove dead viewports:
             self.viewports.retain(|id, _| all_viewport_ids.contains(id));
@@ -1597,12 +1609,6 @@ impl ContextImpl {
             shapes,
             pixels_per_point,
             viewports: out_viewports,
-            // We should not process viewport commands when we are a sync viewport, because that will cause a deadlock for egui backend
-            viewport_commands: if is_last {
-                std::mem::take(&mut self.viewport_commands)
-            } else {
-                Vec::new()
-            },
         }
     }
 }
@@ -2518,7 +2524,7 @@ impl Context {
 
     /// Send a command to a speicfic viewport.
     pub fn viewport_command_for(&self, id: ViewportId, command: ViewportCommand) {
-        self.write(|ctx| ctx.viewport_commands.push((id, command)));
+        self.write(|ctx| ctx.viewport_for(id).commands.push(command));
     }
 
     /// This creates a new native window, if possible.
@@ -2615,10 +2621,7 @@ impl Context {
                 viewport.used = true;
                 viewport.viewport_ui_cb = None; // it is immediate
 
-                ViewportIdPair {
-                    this: new_viewport_id,
-                    parent: parent_viewport_id,
-                }
+                ViewportIdPair::from_self_and_parent(new_viewport_id, parent_viewport_id)
             });
 
             let mut out = None;

crates/egui/src/data/output.rs

@@ -1,6 +1,6 @@
 //! All the data egui returns to the backend at the end of each frame.
 
-use crate::{ViewportCommand, ViewportId, ViewportOutput, WidgetType};
+use crate::{ViewportIdMap, ViewportOutput, WidgetType};
 
 /// What egui emits each frame from [`crate::Context::run`].
 ///
@@ -26,11 +26,8 @@ pub struct FullOutput {
     /// You can pass this to [`crate::Context::tessellate`] together with [`Self::shapes`].
     pub pixels_per_point: f32,
 
-    /// All the active viewports, excluding the root.
-    pub viewports: Vec<ViewportOutput>,
-
-    /// Commands sent to different viewports.
-    pub viewport_commands: Vec<(ViewportId, ViewportCommand)>,
+    /// All the active viewports, including the root.
+    pub viewports: ViewportIdMap<ViewportOutput>,
 }
 
 impl FullOutput {
@@ -41,16 +38,24 @@ impl FullOutput {
             textures_delta,
             shapes,
             pixels_per_point,
-            mut viewports,
-            mut viewport_commands,
+            viewports,
         } = newer;
 
         self.platform_output.append(platform_output);
         self.textures_delta.append(textures_delta);
         self.shapes = shapes; // Only paint the latest
         self.pixels_per_point = pixels_per_point; // Use latest
-        self.viewports.append(&mut viewports);
-        self.viewport_commands.append(&mut viewport_commands);
+
+        for (id, new_viewport) in viewports {
+            match self.viewports.entry(id) {
+                std::collections::hash_map::Entry::Vacant(entry) => {
+                    entry.insert(new_viewport);
+                }
+                std::collections::hash_map::Entry::Occupied(mut entry) => {
+                    entry.get_mut().append(new_viewport);
+                }
+            }
+        }
     }
 }
 

crates/egui/src/viewport.rs

@@ -83,6 +83,11 @@ impl ViewportIdPair {
         this: ViewportId::ROOT,
         parent: ViewportId::ROOT,
     };
+
+    #[inline]
+    pub fn from_self_and_parent(this: ViewportId, parent: ViewportId) -> Self {
+        Self { this, parent }
+    }
 }
 
 /// The user-code that shows the ui in the viewport, used for deferred viewports.
@@ -669,12 +674,30 @@ pub struct ViewportOutput {
     ///
     /// `None` for immediate viewports and the ROOT viewport.
     pub viewport_ui_cb: Option<Arc<ViewportUiCallback>>,
+
+    /// Commands to change the viewport, e.g. window title and size.
+    pub commands: Vec<ViewportCommand>,
 }
 
 impl ViewportOutput {
     pub fn id(&self) -> ViewportId {
         self.ids.this
     }
+
+    /// Add on new output.
+    pub fn append(&mut self, newer: Self) {
+        let Self {
+            ids,
+            builder,
+            viewport_ui_cb,
+            mut commands,
+        } = newer;
+
+        self.ids = ids;
+        self.builder.patch(&builder);
+        self.viewport_ui_cb = viewport_ui_cb;
+        self.commands.append(&mut commands);
+    }
 }
 
 /// Viewport for immediate rendering.