[egui_glium] Add option not to persist app to file

demo_glium/src/main.rs

@@ -1,11 +1,15 @@
 #![deny(warnings)]
 #![warn(clippy::all)]
 
-use egui_glium::storage::FileStorage;
-
 fn main() {
     let title = "Egui glium demo";
-    let storage = FileStorage::from_path(".egui_demo_glium.json".into());
+
+    // Persist app state to file:
+    let storage = egui_glium::storage::FileStorage::from_path(".egui_demo_glium.json".into());
+
+    // Alternative: store nowhere
+    // let storage = egui::app::DummyStorage::default();
+
     let app: egui::DemoApp = egui::app::get_value(&storage, egui::app::APP_KEY).unwrap_or_default();
-    egui_glium::run(title, storage, app);
+    egui_glium::run(title, Box::new(storage), app);
 }

egui/src/app.rs

@@ -75,6 +75,9 @@ pub trait TextureAllocator {
 pub trait Storage {
     fn get_string(&self, key: &str) -> Option<&str>;
     fn set_string(&mut self, key: &str, value: String);
+
+    /// write-to-disk or similar
+    fn flush(&mut self);
 }
 
 /// Stores nothing.
@@ -86,6 +89,7 @@ impl Storage for DummyStorage {
         None
     }
     fn set_string(&mut self, _key: &str, _value: String) {}
+    fn flush(&mut self) {}
 }
 
 #[cfg(feature = "serde_json")]

egui_glium/src/backend.rs

@@ -1,9 +1,6 @@
 use std::time::Instant;
 
-use crate::{
-    storage::{FileStorage, WindowSettings},
-    *,
-};
+use crate::{storage::WindowSettings, *};
 
 pub use egui::{
     app::{self, App, Storage},
@@ -24,7 +21,11 @@ impl egui::app::TextureAllocator for Painter {
 }
 
 /// Run an egui app
-pub fn run(title: &str, mut storage: FileStorage, mut app: impl App + 'static) -> ! {
+pub fn run(
+    title: &str,
+    mut storage: Box<dyn egui::app::Storage>,
+    mut app: impl App + 'static,
+) -> ! {
     let event_loop = glutin::event_loop::EventLoop::new();
     let mut window = glutin::window::WindowBuilder::new()
         .with_decorations(true)
@@ -32,7 +33,8 @@ pub fn run(title: &str, mut storage: FileStorage, mut app: impl App + 'static) -
         .with_title(title)
         .with_transparent(false);
 
-    let window_settings: Option<WindowSettings> = egui::app::get_value(&storage, WINDOW_KEY);
+    let window_settings: Option<WindowSettings> =
+        egui::app::get_value(storage.as_ref(), WINDOW_KEY);
     if let Some(window_settings) = &window_settings {
         window = window_settings.initialize_size(window);
     }
@@ -49,7 +51,7 @@ pub fn run(title: &str, mut storage: FileStorage, mut app: impl App + 'static) -
     }
 
     let mut ctx = egui::Context::new();
-    *ctx.memory() = egui::app::get_value(&storage, EGUI_MEMORY_KEY).unwrap_or_default();
+    *ctx.memory() = egui::app::get_value(storage.as_ref(), EGUI_MEMORY_KEY).unwrap_or_default();
 
     let mut raw_input = egui::RawInput {
         pixels_per_point: Some(native_pixels_per_point(&display)),
@@ -119,13 +121,13 @@ pub fn run(title: &str, mut storage: FileStorage, mut app: impl App + 'static) -
             }
             glutin::event::Event::LoopDestroyed => {
                 egui::app::set_value(
-                    &mut storage,
+                    storage.as_mut(),
                     WINDOW_KEY,
                     &WindowSettings::from_display(&display),
                 );
-                egui::app::set_value(&mut storage, EGUI_MEMORY_KEY, &*ctx.memory());
-                app.on_exit(&mut storage);
-                storage.save();
+                egui::app::set_value(storage.as_mut(), EGUI_MEMORY_KEY, &*ctx.memory());
+                app.on_exit(storage.as_mut());
+                storage.flush();
             }
             _ => (),
         }

egui_glium/src/storage.rs

@@ -18,13 +18,6 @@ impl FileStorage {
             dirty: false,
         }
     }
-
-    pub fn save(&mut self) {
-        if self.dirty {
-            serde_json::to_writer(std::fs::File::create(&self.path).unwrap(), &self.kv).unwrap();
-            self.dirty = false;
-        }
-    }
 }
 
 impl egui::app::Storage for FileStorage {
@@ -38,6 +31,13 @@ impl egui::app::Storage for FileStorage {
             self.dirty = true;
         }
     }
+
+    fn flush(&mut self) {
+        if self.dirty {
+            serde_json::to_writer(std::fs::File::create(&self.path).unwrap(), &self.kv).unwrap();
+            self.dirty = false;
+        }
+    }
 }
 
 // ----------------------------------------------------------------------------

example_glium/src/main.rs

@@ -4,7 +4,6 @@
 #![warn(clippy::all)]
 
 use egui::{Slider, Window};
-use egui_glium::storage::FileStorage;
 
 /// We derive Deserialize/Serialize so we can persist app state on shutdown.
 #[derive(Default, serde::Deserialize, serde::Serialize)]
@@ -44,9 +43,15 @@ impl egui::app::App for MyApp {
 
 fn main() {
     let title = "My Egui Window";
-    let storage = FileStorage::from_path(".egui_example_glium.json".into()); // Where to persist app state
+
+    // Persist app state to file:
+    let storage = egui_glium::storage::FileStorage::from_path(".egui_example_glium.json".into());
+
+    // Alternative: store nowhere
+    // let storage = egui::app::DummyStorage::default();
+
     let app: MyApp = egui::app::get_value(&storage, egui::app::APP_KEY).unwrap_or_default(); // Restore `MyApp` from file, or create new `MyApp`.
-    egui_glium::run(title, storage, app);
+    egui_glium::run(title, Box::new(storage), app);
 }
 
 fn my_save_function() {