Add janky spinner

src/app.rs

@@ -2,11 +2,14 @@ use std::{
     fs,
     path::PathBuf,
     sync::{Arc, mpsc},
+    thread::JoinHandle,
+    time::{Duration, Instant},
 };
 
 use crate::{file_editor::FileEditor, preferences::Preferences, util::GuiSender};
 use egui::{
     Align, Button, Color32, FontData, FontDefinitions, PointerButton, RichText, ScrollArea, Stroke,
+    Ui,
 };
 
 #[derive(serde::Deserialize, serde::Serialize)]
@@ -18,6 +21,8 @@ pub struct App {
     actions_tx: mpsc::Sender<Action>,
     #[serde(skip)]
     actions_rx: mpsc::Receiver<Action>,
+    #[serde(skip)]
+    jobs: Jobs,
 
     tabs: Vec<(TabId, Tab)>,
     open_tab_index: Option<usize>,
@@ -25,6 +30,33 @@ pub struct App {
     next_tab_id: TabId,
 }
 
+pub struct Jobs {
+    handles: Vec<JoinHandle<()>>,
+    actions_tx: mpsc::Sender<Action>,
+}
+
+impl Jobs {
+    fn start(&mut self, ui: &mut Ui, job: impl FnOnce() -> Option<Action> + Send + 'static) {
+        let ctx = ui.ctx().clone();
+        let actions_tx = self.actions_tx.clone();
+        self.handles.push(std::thread::spawn(move || {
+            // start rendering the spinner thingy
+            ctx.request_repaint();
+
+            let start = Instant::now();
+
+            if let Some(action) = job() {
+                let _ = actions_tx.send(action);
+                ctx.request_repaint();
+            };
+
+            // Make sure that task takes at least 250ms to run, so that the spinner won't blink
+            let sleep_for = Duration::from_millis(250).saturating_sub(start.elapsed());
+            std::thread::sleep(sleep_for);
+        }));
+    }
+}
+
 #[derive(serde::Deserialize, serde::Serialize)]
 enum Tab {
     File(FileEditor),
@@ -55,8 +87,12 @@ impl Default for App {
         let (actions_tx, actions_rx) = mpsc::channel();
         Self {
             preferences: Preferences::default(),
-            actions_tx,
+            actions_tx: actions_tx.clone(/* this is silly, i know */),
             actions_rx,
+            jobs: Jobs {
+                handles: Default::default(),
+                actions_tx,
+            },
             tabs: vec![(1, Tab::File(FileEditor::new("note.md")))],
             open_tab_index: None,
             next_tab_id: 2,
@@ -178,6 +214,8 @@ impl eframe::App for App {
     fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
         self.preferences.apply(ctx);
 
+        self.jobs.handles.retain(|job| !job.is_finished());
+
         while let Ok(action) = self.actions_rx.try_recv() {
             self.handle_action(action);
         }
@@ -205,22 +243,15 @@ impl eframe::App for App {
 
                     #[cfg(not(target_arch = "wasm32"))]
                     if ui.button("Open File").clicked() {
-                        let actions_tx = self.actions_tx(ui.ctx());
-                        std::thread::spawn(move || {
-                            let file = rfd::FileDialog::new().pick_file();
+                        self.jobs.start(ui, move || {
+                            let file_path = rfd::FileDialog::new().pick_file()?;
 
-                            let Some(file_path) = file else { return };
-
-                            let text = match fs::read_to_string(&file_path) {
-                                Ok(text) => text,
-                                Err(e) => {
-                                    log::error!("Failed to read {file_path:?}: {e}");
-                                    return;
-                                }
-                            };
+                            let text = fs::read_to_string(&file_path)
+                                .inspect_err(|e| log::error!("Failed to read {file_path:?}: {e}"))
+                                .ok()?;
 
                             let editor = FileEditor::from_file(file_path, &text);
-                            let _ = actions_tx.send(Action::OpenFile(editor));
+                            Some(Action::OpenFile(editor))
                         });
                     }
 
@@ -255,10 +286,11 @@ impl eframe::App for App {
                         if let Some((file_path, file_editor)) = open_file_with_path {
                             let text = file_editor.to_string();
                             let file_path = file_path.to_owned();
-                            std::thread::spawn(move || {
+                            self.jobs.start(ui, move || {
                                 if let Err(e) = fs::write(file_path, text.as_bytes()) {
                                     log::error!("{e}");
                                 };
+                                None
                             });
                         }
                     }
@@ -268,21 +300,17 @@ impl eframe::App for App {
                         .add_enabled(open_file.is_some(), Button::new("Save As"))
                         .clicked()
                     {
-                        let actions_tx = self.actions_tx(ui.ctx());
                         let (tab_id, editor) =
                             open_file.expect("We checked that open_file is_some");
                         let text = editor.to_string();
-                        std::thread::spawn(move || {
-                            let Some(file_path) = rfd::FileDialog::new().save_file() else {
-                                return;
-                            };
+                        self.jobs.start(ui, move || {
+                            let file_path = rfd::FileDialog::new().save_file()?;
 
-                            if let Err(e) = fs::write(&file_path, text.as_bytes()) {
-                                log::error!("{e}");
-                                return;
-                            };
+                            fs::write(&file_path, text.as_bytes())
+                                .inspect_err(|e| log::error!("{e}"))
+                                .ok()?;
 
-                            let _ = actions_tx.send(Action::MoveFile(tab_id, file_path));
+                            Some(Action::MoveFile(tab_id, file_path))
                         });
                     }
 
@@ -297,6 +325,10 @@ impl eframe::App for App {
                     }
                 });
 
+                if !self.jobs.handles.is_empty() {
+                    ui.spinner();
+                }
+
                 ui.add_space(16.0);
 
                 ui.add_space(16.0);