[egui_web] Auto-save app state to Local Storage every 30 seconds

demo_glium/Cargo.toml

@@ -6,6 +6,6 @@ license = "MIT OR Apache-2.0"
 edition = "2018"
 
 [dependencies]
-egui = { path = "../egui", features = ["serde"] }
+egui = { path = "../egui", features = ["serde", "serde_json"] }
 egui_glium = { path = "../egui_glium" }
 serde = { version = "1", features = ["derive"] }

demo_web/Cargo.toml

@@ -9,7 +9,7 @@ edition = "2018"
 crate-type = ["cdylib", "rlib"]
 
 [dependencies]
-egui = { path = "../egui", features = ["serde"] }
+egui = { path = "../egui", features = ["serde", "serde_json"] }
 egui_web = { path = "../egui_web" }
 js-sys = "0.3"
 serde = { version = "1", features = ["derive"] }

egui/src/app.rs

@@ -19,6 +19,20 @@ pub trait App {
         crate::Srgba::from_rgb(16, 16, 16).into()
     }
 
+    /// Called once on start. Allows you to restore state.
+    fn load(&mut self, _storage: &dyn Storage) {}
+
+    /// Called on shutdown, and perhaps at regular intervals. Allows you to save state.
+    fn save(&mut self, _storage: &mut dyn Storage) {}
+
+    /// Time between automatic calls to `save()`
+    fn auto_save_interval(&self) -> std::time::Duration {
+        std::time::Duration::from_secs(30)
+    }
+
+    /// Called once on shutdown (before or after `save()`)
+    fn on_exit(&mut self) {}
+
     /// Called once before the first frame.
     /// Allows you to do setup code and to call `ctx.set_fonts()`.
     /// Optional.
@@ -27,9 +41,6 @@ pub trait App {
     /// Called each time the UI needs repainting, which may be many times per second.
     /// Put your widgets into a `SidePanel`, `TopPanel`, `CentralPanel`, `Window` or `Area`.
     fn ui(&mut self, ctx: &crate::CtxRef, integration_context: &mut IntegrationContext<'_>);
-
-    /// Called once on shutdown. Allows you to save state.
-    fn on_exit(&mut self, _storage: &mut dyn Storage) {}
 }
 
 pub struct IntegrationContext<'a> {

egui/src/demos/app.rs

@@ -281,6 +281,16 @@ impl app::App for DemoApp {
         "Egui Demo"
     }
 
+    #[cfg(feature = "serde_json")]
+    fn load(&mut self, storage: &dyn crate::app::Storage) {
+        *self = crate::app::get_value(storage, crate::app::APP_KEY).unwrap_or_default()
+    }
+
+    #[cfg(feature = "serde_json")]
+    fn save(&mut self, storage: &mut dyn crate::app::Storage) {
+        crate::app::set_value(storage, crate::app::APP_KEY, self);
+    }
+
     fn ui(&mut self, ctx: &CtxRef, integration_context: &mut crate::app::IntegrationContext<'_>) {
         self.frame_history
             .on_new_frame(ctx.input().time, integration_context.info.cpu_usage);
@@ -339,9 +349,4 @@ impl app::App for DemoApp {
             ctx.request_repaint();
         }
     }
-
-    #[cfg(feature = "serde_json")]
-    fn on_exit(&mut self, storage: &mut dyn app::Storage) {
-        app::set_value(storage, app::APP_KEY, self);
-    }
 }

egui_glium/src/backend.rs

@@ -65,6 +65,7 @@ fn create_display(
 
 /// Run an egui app
 pub fn run(mut storage: Box<dyn egui::app::Storage>, mut app: Box<dyn App>) -> ! {
+    app.load(storage.as_ref());
     let window_settings: Option<WindowSettings> =
         egui::app::get_value(storage.as_ref(), WINDOW_KEY);
     let event_loop = glutin::event_loop::EventLoop::with_user_event();
@@ -85,7 +86,7 @@ pub fn run(mut storage: Box<dyn egui::app::Storage>, mut app: Box<dyn App>) -> !
 
     event_loop.run(move |event, _, control_flow| {
         let mut redraw = || {
-            let egui_start = Instant::now();
+            let frame_start = Instant::now();
             input_state.raw.time = Some(start_time.elapsed().as_nanos() as f64 * 1e-9);
             input_state.raw.screen_rect = Some(Rect::from_min_size(
                 Default::default(),
@@ -109,7 +110,7 @@ pub fn run(mut storage: Box<dyn egui::app::Storage>, mut app: Box<dyn App>) -> !
             let (egui_output, paint_commands) = ctx.end_frame();
             let paint_jobs = ctx.tesselate(paint_commands);
 
-            let frame_time = (Instant::now() - egui_start).as_secs_f64() as f32;
+            let frame_time = (Instant::now() - frame_start).as_secs_f64() as f32;
             previous_frame_time = Some(frame_time);
             painter.paint_jobs(
                 &display,
@@ -172,7 +173,8 @@ pub fn run(mut storage: Box<dyn egui::app::Storage>, mut app: Box<dyn App>) -> !
                     &WindowSettings::from_display(&display),
                 );
                 egui::app::set_value(storage.as_mut(), EGUI_MEMORY_KEY, &*ctx.memory());
-                app.on_exit(storage.as_mut());
+                app.save(storage.as_mut());
+                app.on_exit();
                 storage.flush();
             }
 

egui_web/CHANGELOG.md

@@ -7,6 +7,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
+### Added ⭐
+
+* Auto-save of app state to local storage
+
 ### Changed ⭐
 
 * Set a maximum canvas size to alleviate performance issues on some machines

egui_web/src/backend.rs

@@ -12,19 +12,16 @@ pub struct WebBackend {
     painter: webgl::Painter,
     previous_frame_time: Option<f32>,
     frame_start: Option<f64>,
-    last_save_time: Option<f64>,
 }
 
 impl WebBackend {
     pub fn new(canvas_id: &str) -> Result<Self, JsValue> {
         let ctx = egui::CtxRef::default();
-        load_memory(&ctx);
         Ok(Self {
             ctx,
             painter: webgl::Painter::new(canvas_id)?,
             previous_frame_time: None,
             frame_start: None,
-            last_save_time: None,
         })
     }
 
@@ -47,8 +44,6 @@ impl WebBackend {
         let (output, paint_commands) = self.ctx.end_frame();
         let paint_jobs = self.ctx.tesselate(paint_commands);
 
-        self.auto_save();
-
         let now = now_sec();
         self.previous_frame_time = Some((now - frame_start) as f32);
 
@@ -68,16 +63,6 @@ impl WebBackend {
         )
     }
 
-    pub fn auto_save(&mut self) {
-        let now = now_sec();
-        let time_since_last_save = now - self.last_save_time.unwrap_or(std::f64::NEG_INFINITY);
-        const AUTO_SAVE_INTERVAL: f64 = 5.0;
-        if time_since_last_save > AUTO_SAVE_INTERVAL {
-            self.last_save_time = Some(now);
-            save_memory(&self.ctx);
-        }
-    }
-
     pub fn painter_debug_info(&self) -> String {
         self.painter.debug_info()
     }
@@ -159,19 +144,37 @@ pub struct AppRunner {
     pub input: WebInput,
     pub app: Box<dyn App>,
     pub needs_repaint: std::sync::Arc<NeedRepaint>,
+    pub storage: LocalStorage,
+    pub last_save_time: f64,
 }
 
 impl AppRunner {
     pub fn new(web_backend: WebBackend, mut app: Box<dyn App>) -> Result<Self, JsValue> {
+        load_memory(&web_backend.ctx);
+        let storage = LocalStorage::default();
+        app.load(&storage);
         app.setup(&web_backend.ctx);
         Ok(Self {
             web_backend,
             input: Default::default(),
             app,
             needs_repaint: Default::default(),
+            storage,
+            last_save_time: now_sec(),
         })
     }
 
+    pub fn auto_save(&mut self) {
+        let now = now_sec();
+        let time_since_last_save = now - self.last_save_time;
+
+        if time_since_last_save > self.app.auto_save_interval().as_secs_f64() {
+            save_memory(&self.web_backend.ctx);
+            self.app.save(&mut self.storage);
+            self.last_save_time = now;
+        }
+    }
+
     pub fn canvas_id(&self) -> &str {
         self.web_backend.canvas_id()
     }

egui_web/src/lib.rs

@@ -152,7 +152,7 @@ pub fn load_memory(ctx: &egui::Context) {
                 *ctx.memory() = memory;
             }
             Err(err) => {
-                console_log(format!("ERROR: Failed to parse memory json: {}", err));
+                console_error(format!("Failed to parse memory json: {}", err));
             }
         }
     }
@@ -164,14 +164,12 @@ pub fn save_memory(ctx: &egui::Context) {
             local_storage_set("egui_memory_json", &json);
         }
         Err(err) => {
-            console_log(format!(
-                "ERROR: Failed to serialize memory as json: {}",
-                err
-            ));
+            console_error(format!("Failed to serialize memory as json: {}", err));
         }
     }
 }
 
+#[derive(Default)]
 pub struct LocalStorage {}
 
 impl egui::app::Storage for LocalStorage {
@@ -220,7 +218,7 @@ pub fn set_clipboard_text(s: &str) {
         let future = wasm_bindgen_futures::JsFuture::from(promise);
         let future = async move {
             if let Err(err) = future.await {
-                console_log(format!("Copy/cut action denied: {:?}", err));
+                console_error(format!("Copy/cut action denied: {:?}", err));
             }
         };
         wasm_bindgen_futures::spawn_local(future);
@@ -341,7 +339,9 @@ fn paint_and_schedule(runner_ref: AppRunnerRef) -> Result<(), JsValue> {
             if output.needs_repaint {
                 runner_lock.needs_repaint.set_true();
             }
+            runner_lock.auto_save();
         }
+
         Ok(())
     }