Add support for user-provided event loops & event handlers (#3180)

* added support for custom event loop
* added support for custom event callbacks

packages/desktop/src/config.rs

@@ -1,12 +1,22 @@
 use dioxus_core::LaunchConfig;
 use std::borrow::Cow;
 use std::path::PathBuf;
+use tao::event_loop::{EventLoop, EventLoopWindowTarget};
 use tao::window::{Icon, WindowBuilder};
 use wry::http::{Request as HttpRequest, Response as HttpResponse};
 use wry::RequestAsyncResponder;
 
+use crate::ipc::UserWindowEvent;
 use crate::menubar::{default_menu_bar, DioxusMenu};
 
+type CustomEventHandler = Box<
+    dyn 'static
+        + for<'a> FnMut(
+            &tao::event::Event<'a, UserWindowEvent>,
+            &EventLoopWindowTarget<UserWindowEvent>,
+        ),
+>;
+
 /// The behaviour of the application when the last window is closed.
 #[derive(Copy, Clone, Eq, PartialEq)]
 #[non_exhaustive]
@@ -37,6 +47,7 @@ impl From<MenuBuilderState> for Option<DioxusMenu> {
 
 /// The configuration for the desktop application.
 pub struct Config {
+    pub(crate) event_loop: Option<EventLoop<UserWindowEvent>>,
     pub(crate) window: WindowBuilder,
     pub(crate) menu: MenuBuilderState,
     pub(crate) protocols: Vec<WryProtocol>,
@@ -50,6 +61,7 @@ pub struct Config {
     pub(crate) root_name: String,
     pub(crate) background_color: Option<(u8, u8, u8, u8)>,
     pub(crate) last_window_close_behavior: WindowCloseBehaviour,
+    pub(crate) custom_event_handler: Option<CustomEventHandler>,
 }
 
 impl LaunchConfig for Config {}
@@ -80,6 +92,7 @@ impl Config {
 
         Self {
             window,
+            event_loop: None,
             menu: MenuBuilderState::Unset,
             protocols: Vec::new(),
             asynchronous_protocols: Vec::new(),
@@ -92,6 +105,7 @@ impl Config {
             root_name: "main".to_string(),
             background_color: None,
             last_window_close_behavior: WindowCloseBehaviour::LastWindowExitsApp,
+            custom_event_handler: None,
         }
     }
 
@@ -121,6 +135,12 @@ impl Config {
         self
     }
 
+    /// Set the event loop to be used
+    pub fn with_event_loop(mut self, event_loop: EventLoop<UserWindowEvent>) -> Self {
+        self.event_loop = Some(event_loop);
+        self
+    }
+
     /// Set the configuration for the window.
     pub fn with_window(mut self, window: WindowBuilder) -> Self {
         // We need to do a swap because the window builder only takes itself as muy self
@@ -138,6 +158,16 @@ impl Config {
         self
     }
 
+    /// Sets a custom callback to run whenever the event pool receives an event.
+    pub fn with_custom_event_handler(
+        mut self,
+        f: impl FnMut(&tao::event::Event<'_, UserWindowEvent>, &EventLoopWindowTarget<UserWindowEvent>)
+            + 'static,
+    ) -> Self {
+        self.custom_event_handler = Some(Box::new(f));
+        self
+    }
+
     /// Set a custom protocol
     pub fn with_custom_protocol<F>(mut self, name: impl ToString, handler: F) -> Self
     where