Handle for app from WehHandle

eframe/src/epi.rs

@@ -6,6 +6,9 @@
 
 #![warn(missing_docs)] // Let's keep `epi` well-documented.
 
+#[cfg(target_arch = "wasm32")]
+use std::any::Any;
+
 /// This is how your app is created.
 ///
 /// You can use the [`CreationContext`] to setup egui, restore state, setup OpenGL things, etc.
@@ -49,6 +52,15 @@ pub trait App {
     /// To force a repaint, call [`egui::Context::request_repaint`] at any time (e.g. from another thread).
     fn update(&mut self, ctx: &egui::Context, frame: &mut Frame);
 
+    // Handle to the app.
+    //
+    // Can be used from web to interact or other external context
+    // Implementation is needed, because downcasting Box<dyn App> -> Box<dyn Any> to get &ConcreteApp is not simple in current rust.
+    //
+    // Just return &mut *self
+    #[cfg(target_arch = "wasm32")]
+    fn as_any_mut(&mut self) -> &mut dyn Any;
+
     /// Called on shutdown, and perhaps at regular intervals. Allows you to save state.
     ///
     /// Only called when the "persistence" feature is enabled.

eframe/src/web/backend.rs

@@ -35,7 +35,7 @@ impl WebInput {
 
 // ----------------------------------------------------------------------------
 
-use std::sync::atomic::Ordering::SeqCst;
+use std::{any::Any, sync::atomic::Ordering::SeqCst};
 
 /// Stores when to do the next repaint.
 pub struct NeedRepaint(Mutex<f64>);
@@ -265,6 +265,10 @@ impl AppRunner {
         &self.egui_ctx
     }
 
+    pub fn get_app_mut(&mut self) -> &mut dyn Any {
+        self.app.as_any_mut()
+    }
+
     pub fn auto_save(&mut self) {
         let now = now_sec();
         let time_since_last_save = now - self.last_save_time;