Viewer's command queue is now a channel, allowing to queue commands w…

…ithout mutable access (#2339)

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### What

Allows for decoupling a bunch of things!
The good parts from #2333 ;)

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)

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PR Build Summary: https://build.rerun.io/pr/2339

<!-- pr-link-docs:start -->
Docs preview: https://rerun.io/preview/c58f5af/docs
Examples preview: https://rerun.io/preview/c58f5af/examples
<!-- pr-link-docs:end -->

---------

Co-authored-by: Jeremy Leibs <[email protected]>

crates/re_ui/Cargo.toml

@@ -29,8 +29,9 @@ eframe = ["dep:eframe"]
 
 
 [dependencies]
-egui.workspace = true
+crossbeam.workspace = true
 egui_extras.workspace = true
+egui.workspace = true
 image = { workspace = true, default-features = false, features = ["png"] }
 parking_lot.workspace = true
 serde = { version = "1", features = ["derive"] }

crates/re_ui/examples/re_ui_example.rs

@@ -1,4 +1,4 @@
-use re_ui::{toasts, Command, CommandPalette};
+use re_ui::{toasts, Command, CommandPalette, CommandReceiver, CommandSender};
 
 fn main() -> eframe::Result<()> {
     re_log::setup_native_logging();
@@ -49,7 +49,8 @@ pub struct ExampleApp {
     cmd_palette: CommandPalette,
 
     /// Commands to run at the end of the frame.
-    pending_commands: Vec<Command>,
+    pub command_sender: CommandSender,
+    command_receiver: CommandReceiver,
     latest_cmd: String,
 }
 
@@ -60,6 +61,8 @@ impl ExampleApp {
 
         let tree = egui_tiles::Tree::new_tabs(vec![1, 2, 3]);
 
+        let (command_sender, command_receiver) = re_ui::command_channel();
+
         Self {
             re_ui,
             toasts: Default::default(),
@@ -74,7 +77,8 @@ impl ExampleApp {
             dummy_bool: true,
 
             cmd_palette: CommandPalette::default(),
-            pending_commands: Default::default(),
+            command_sender,
+            command_receiver,
             latest_cmd: Default::default(),
         }
     }
@@ -205,13 +209,13 @@ impl eframe::App for ExampleApp {
             });
 
         if let Some(cmd) = self.cmd_palette.show(egui_ctx) {
-            self.pending_commands.push(cmd);
+            self.command_sender.send(cmd);
         }
         if let Some(cmd) = re_ui::Command::listen_for_kb_shortcut(egui_ctx) {
-            self.pending_commands.push(cmd);
+            self.command_sender.send(cmd);
         }
 
-        for cmd in self.pending_commands.drain(..) {
+        while let Some(cmd) = self.command_receiver.recv() {
             self.latest_cmd = cmd.text().to_owned();
 
             #[allow(clippy::single_match)]
@@ -248,7 +252,7 @@ impl ExampleApp {
                     ui.set_height(top_bar_style.height);
                     ui.add_space(top_bar_style.indent);
 
-                    ui.menu_button("File", |ui| file_menu(ui, &mut self.pending_commands));
+                    ui.menu_button("File", |ui| file_menu(ui, &self.command_sender));
 
                     self.top_bar_ui(ui, frame);
                 })
@@ -297,11 +301,11 @@ impl ExampleApp {
     }
 }
 
-fn file_menu(ui: &mut egui::Ui, pending_commands: &mut Vec<Command>) {
-    Command::Save.menu_button_ui(ui, pending_commands);
-    Command::SaveSelection.menu_button_ui(ui, pending_commands);
-    Command::Open.menu_button_ui(ui, pending_commands);
-    Command::Quit.menu_button_ui(ui, pending_commands);
+fn file_menu(ui: &mut egui::Ui, command_sender: &CommandSender) {
+    Command::Save.menu_button_ui(ui, command_sender);
+    Command::SaveSelection.menu_button_ui(ui, command_sender);
+    Command::Open.menu_button_ui(ui, command_sender);
+    Command::Quit.menu_button_ui(ui, command_sender);
 }
 
 fn selection_buttons(ui: &mut egui::Ui) {

crates/re_ui/src/command.rs

@@ -1,5 +1,34 @@
 use egui::{Key, KeyboardShortcut, Modifiers};
 
+/// Sender that queues up the execution of a command.
+pub struct CommandSender(crossbeam::channel::Sender<Command>);
+
+impl CommandSender {
+    /// Send a command to be executed.
+    pub fn send(&self, command: Command) {
+        // The only way this can fail is if the receiver has been dropped.
+        self.0.send(command).ok();
+    }
+}
+
+/// Receiver for the [`CommandSender`]
+pub struct CommandReceiver(crossbeam::channel::Receiver<Command>);
+
+impl CommandReceiver {
+    /// Receive a command to be executed if any is queued.
+    pub fn recv(&self) -> Option<Command> {
+        // The only way this can fail (other than being empty)
+        // is if the sender has been dropped.
+        self.0.try_recv().ok()
+    }
+}
+
+/// Creates a new command channel.
+pub fn command_channel() -> (CommandSender, CommandReceiver) {
+    let (sender, receiver) = crossbeam::channel::unbounded();
+    (CommandSender(sender), CommandReceiver(receiver))
+}
+
 /// All the commands we support.
 ///
 /// Most are available in the GUI,
@@ -232,12 +261,12 @@ impl Command {
     pub fn menu_button_ui(
         self,
         ui: &mut egui::Ui,
-        pending_commands: &mut Vec<Command>,
+        command_sender: &CommandSender,
     ) -> egui::Response {
         let button = self.menu_button(ui.ctx());
         let response = ui.add(button).on_hover_text(self.tooltip());
         if response.clicked() {
-            pending_commands.push(self);
+            command_sender.send(self);
             ui.close_menu();
         }
         response

crates/re_ui/src/lib.rs

@@ -10,7 +10,7 @@ mod static_image_cache;
 pub mod toasts;
 mod toggle_switch;
 
-pub use command::Command;
+pub use command::{command_channel, Command, CommandReceiver, CommandSender};
 pub use command_palette::CommandPalette;
 pub use design_tokens::DesignTokens;
 pub use icons::Icon;

crates/re_viewer/src/app.rs

@@ -6,7 +6,7 @@ use re_data_store::store_db::StoreDb;
 use re_log_types::{ApplicationId, LogMsg, StoreId, StoreKind};
 use re_renderer::WgpuResourcePoolStatistics;
 use re_smart_channel::Receiver;
-use re_ui::{toasts, Command};
+use re_ui::{toasts, Command, CommandReceiver, CommandSender};
 use re_viewer_context::{
     AppOptions, ComponentUiRegistry, DynSpaceViewClass, PlayState, SpaceViewClassRegistry,
     SpaceViewClassRegistryError,
@@ -108,7 +108,8 @@ pub struct App {
     pub(crate) frame_time_history: egui::util::History<f32>,
 
     /// Commands to run at the end of the frame.
-    pub(crate) pending_commands: Vec<Command>,
+    pub command_sender: CommandSender,
+    command_receiver: CommandReceiver,
     cmd_palette: re_ui::CommandPalette,
 
     analytics: ViewerAnalytics,
@@ -164,6 +165,8 @@ impl App {
             screenshotter.screenshot_to_path_then_quit(screenshot_path);
         }
 
+        let (command_sender, command_receiver) = re_ui::command_channel();
+
         Self {
             build_info,
             startup_options,
@@ -188,7 +191,8 @@ impl App {
 
             frame_time_history: egui::util::History::new(1..100, 0.5),
 
-            pending_commands: Default::default(),
+            command_sender,
+            command_receiver,
             cmd_palette: Default::default(),
 
             space_view_class_registry,
@@ -237,9 +241,9 @@ impl App {
         self.space_view_class_registry.add::<T>()
     }
 
-    fn check_keyboard_shortcuts(&mut self, egui_ctx: &egui::Context) {
+    fn check_keyboard_shortcuts(&self, egui_ctx: &egui::Context) {
         if let Some(cmd) = Command::listen_for_kb_shortcut(egui_ctx) {
-            self.pending_commands.push(cmd);
+            self.command_sender.send(cmd);
         }
     }
 
@@ -249,8 +253,7 @@ impl App {
         egui_ctx: &egui::Context,
         frame: &mut eframe::Frame,
     ) {
-        let commands = self.pending_commands.drain(..).collect_vec();
-        for cmd in commands {
+        while let Some(cmd) = self.command_receiver.recv() {
             self.run_command(cmd, blueprint, frame, egui_ctx);
         }
     }
@@ -906,7 +909,7 @@ impl eframe::App for App {
         }
 
         if let Some(cmd) = self.cmd_palette.show(egui_ctx) {
-            self.pending_commands.push(cmd);
+            self.command_sender.send(cmd);
         }
 
         self.run_pending_commands(&mut blueprint, egui_ctx, frame);

crates/re_viewer/src/ui/rerun_menu.rs

@@ -26,13 +26,13 @@ pub fn rerun_menu_button_ui(ui: &mut egui::Ui, frame: &mut eframe::Frame, app: &
 
         ui.add_space(spacing);
 
-        Command::ToggleCommandPalette.menu_button_ui(ui, &mut app.pending_commands);
+        Command::ToggleCommandPalette.menu_button_ui(ui, &app.command_sender);
 
         ui.add_space(spacing);
 
         #[cfg(not(target_arch = "wasm32"))]
         {
-            Command::Open.menu_button_ui(ui, &mut app.pending_commands);
+            Command::Open.menu_button_ui(ui, &app.command_sender);
 
             save_buttons_ui(ui, app);
 
@@ -42,24 +42,24 @@ pub fn rerun_menu_button_ui(ui: &mut egui::Ui, frame: &mut eframe::Frame, app: &
             let zoom_factor = app.app_options().zoom_factor;
             ui.weak(format!("Zoom {:.0}%", zoom_factor * 100.0))
                 .on_hover_text("The zoom factor applied on top of the OS scaling factor.");
-            Command::ZoomIn.menu_button_ui(ui, &mut app.pending_commands);
-            Command::ZoomOut.menu_button_ui(ui, &mut app.pending_commands);
+            Command::ZoomIn.menu_button_ui(ui, &app.command_sender);
+            Command::ZoomOut.menu_button_ui(ui, &app.command_sender);
             ui.add_enabled_ui(zoom_factor != 1.0, |ui| {
-                Command::ZoomReset.menu_button_ui(ui, &mut app.pending_commands)
+                Command::ZoomReset.menu_button_ui(ui, &app.command_sender)
             });
 
-            Command::ToggleFullscreen.menu_button_ui(ui, &mut app.pending_commands);
+            Command::ToggleFullscreen.menu_button_ui(ui, &app.command_sender);
 
             ui.add_space(spacing);
         }
 
         {
-            Command::ResetViewer.menu_button_ui(ui, &mut app.pending_commands);
+            Command::ResetViewer.menu_button_ui(ui, &app.command_sender);
 
             #[cfg(not(target_arch = "wasm32"))]
-            Command::OpenProfiler.menu_button_ui(ui, &mut app.pending_commands);
+            Command::OpenProfiler.menu_button_ui(ui, &app.command_sender);
 
-            Command::ToggleMemoryPanel.menu_button_ui(ui, &mut app.pending_commands);
+            Command::ToggleMemoryPanel.menu_button_ui(ui, &app.command_sender);
         }
 
         ui.add_space(spacing);
@@ -85,7 +85,7 @@ pub fn rerun_menu_button_ui(ui: &mut egui::Ui, frame: &mut eframe::Frame, app: &
         #[cfg(not(target_arch = "wasm32"))]
         {
             ui.add_space(spacing);
-            Command::Quit.menu_button_ui(ui, &mut app.pending_commands);
+            Command::Quit.menu_button_ui(ui, &app.command_sender);
         }
     });
 }
@@ -280,7 +280,7 @@ fn save_buttons_ui(ui: &mut egui::Ui, app: &mut App) {
                 .clicked()
             {
                 ui.close_menu();
-                app.pending_commands.push(Command::Save);
+                app.command_sender.send(Command::Save);
             }
 
             // We need to know the loop selection _before_ we can even display the
@@ -297,7 +297,7 @@ fn save_buttons_ui(ui: &mut egui::Ui, app: &mut App) {
                 .clicked()
             {
                 ui.close_menu();
-                app.pending_commands.push(Command::SaveSelection);
+                app.command_sender.send(Command::SaveSelection);
             }
         });
     }

crates/re_viewer/src/ui/top_panel.rs

@@ -96,7 +96,7 @@ fn top_bar_ui(
             ))
             .clicked()
         {
-            app.pending_commands.push(Command::ToggleSelectionPanel);
+            app.command_sender.send(Command::ToggleSelectionPanel);
         }
 
         let mut time_panel_expanded = blueprint.time_panel_expanded;
@@ -113,7 +113,7 @@ fn top_bar_ui(
             ))
             .clicked()
         {
-            app.pending_commands.push(Command::ToggleTimePanel);
+            app.command_sender.send(Command::ToggleTimePanel);
         }
 
         let mut blueprint_panel_expanded = blueprint.blueprint_panel_expanded;
@@ -130,7 +130,7 @@ fn top_bar_ui(
             ))
             .clicked()
         {
-            app.pending_commands.push(Command::ToggleBlueprintPanel);
+            app.command_sender.send(Command::ToggleBlueprintPanel);
         }
 
         if cfg!(debug_assertions) && app.app_options().show_metrics {
@@ -143,7 +143,7 @@ fn top_bar_ui(
     });
 }
 
-fn frame_time_label_ui(ui: &mut egui::Ui, app: &mut App) {
+fn frame_time_label_ui(ui: &mut egui::Ui, app: &App) {
     if let Some(frame_time) = app.frame_time_history.average() {
         let ms = frame_time * 1e3;