Derive Reflect + FromReflect for window event types (#6235)

# Objective

The window event types currently don't support reflection. This PR adds support to them (as requested [here](#6223 (comment))).

## Solution

Implement `Reflect` + `FromReflect` for window event types. Relevant traits are also being reflected with `#[reflect(...)]` attributes.

Additionally, this PR derives `Reflect` + `FromReflect` for `WindowDescriptor` and the types it depends on so that `CreateWindow` events can be fully manipulated through reflection.

Finally, this PR adds `FromReflect` for `PathBuf` as a value type, which is needed for `FileDragAndDrop`.

This adds the "glam" feature to the `bevy_reflect` dependency for package `bevy_window`. Since `bevy_window` transitively depends on `glam` already, all this brings in are the reflection `impl`s.

## Open questions

Should `app.register_type::<PathBuf>();` be moved to `CorePlugin`? I added it to `WindowPlugin` because that's where it's used and `CorePlugin` doesn't seem to register all the missing std types, but it would also make sense in `CorePlugin` I believe since it's a commonly used type.

---

## Changelog

Added:
- Implemented `Reflect` + `FromReflect` for window events and related types. These types are automatically registered when adding the `WindowPlugin`.

crates/bevy_window/Cargo.toml

@@ -17,7 +17,9 @@ serialize = ["serde"]
 bevy_app = { path = "../bevy_app", version = "0.9.0" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.9.0" }
 bevy_math = { path = "../bevy_math", version = "0.9.0" }
-bevy_reflect = { path = "../bevy_reflect", version = "0.9.0" }
+bevy_reflect = { path = "../bevy_reflect", version = "0.9.0", features = [
+    "glam",
+] }
 bevy_utils = { path = "../bevy_utils", version = "0.9.0" }
 # Used for close_on_esc
 bevy_input = { path = "../bevy_input", version = "0.9.0" }

crates/bevy_window/src/event.rs

@@ -2,10 +2,19 @@ use std::path::PathBuf;
 
 use super::{WindowDescriptor, WindowId};
 use bevy_math::{IVec2, Vec2};
+use bevy_reflect::{FromReflect, Reflect};
+
+#[cfg(feature = "serialize")]
+use bevy_reflect::{ReflectDeserialize, ReflectSerialize};
 
 /// A window event that is sent whenever a window's logical size has changed.
-#[derive(Debug, Clone, PartialEq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowResized {
     pub id: WindowId,
     /// The new logical width of the window.
@@ -15,25 +24,40 @@ pub struct WindowResized {
 }
 
 /// An event that indicates that a new window should be created.
-#[derive(Debug, Clone, PartialEq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct CreateWindow {
     pub id: WindowId,
     pub descriptor: WindowDescriptor,
 }
 
 /// An event that indicates the window should redraw, even if its control flow is set to `Wait` and
 /// there have been no window events.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct RequestRedraw;
 
 /// An event that is sent whenever a new window is created.
 ///
 /// To create a new window, send a [`CreateWindow`] event - this
 /// event will be sent in the handler for that event.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowCreated {
     pub id: WindowId,
 }
@@ -49,8 +73,13 @@ pub struct WindowCreated {
 /// [`WindowPlugin`]: crate::WindowPlugin
 /// [`Window`]: crate::Window
 /// [closing]: crate::Window::close
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowCloseRequested {
     pub id: WindowId,
 }
@@ -59,11 +88,17 @@ pub struct WindowCloseRequested {
 /// handler for [`Window::close`].
 ///
 /// [`Window::close`]: crate::Window::close
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowClosed {
     pub id: WindowId,
 }
+
 /// An event reporting that the mouse cursor has moved on a window.
 ///
 /// The event is sent only if the cursor is over one of the application's windows.
@@ -73,62 +108,105 @@ pub struct WindowClosed {
 ///
 /// [`WindowEvent::CursorMoved`]: https://docs.rs/winit/latest/winit/event/enum.WindowEvent.html#variant.CursorMoved
 /// [`MouseMotion`]: bevy_input::mouse::MouseMotion
-#[derive(Debug, Clone, PartialEq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct CursorMoved {
     /// The identifier of the window the cursor has moved on.
     pub id: WindowId,
 
     /// The position of the cursor, in window coordinates.
     pub position: Vec2,
 }
+
 /// An event that is sent whenever the user's cursor enters a window.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct CursorEntered {
     pub id: WindowId,
 }
+
 /// An event that is sent whenever the user's cursor leaves a window.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct CursorLeft {
     pub id: WindowId,
 }
 
 /// An event that is sent whenever a window receives a character from the OS or underlying system.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct ReceivedCharacter {
     pub id: WindowId,
     pub char: char,
 }
 
 /// An event that indicates a window has received or lost focus.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowFocused {
     pub id: WindowId,
     pub focused: bool,
 }
 
 /// An event that indicates a window's scale factor has changed.
-#[derive(Debug, Clone, PartialEq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowScaleFactorChanged {
     pub id: WindowId,
     pub scale_factor: f64,
 }
+
 /// An event that indicates a window's OS-reported scale factor has changed.
-#[derive(Debug, Clone, PartialEq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowBackendScaleFactorChanged {
     pub id: WindowId,
     pub scale_factor: f64,
 }
 
 /// Events related to files being dragged and dropped on a window.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub enum FileDragAndDrop {
     DroppedFile { id: WindowId, path_buf: PathBuf },
 
@@ -138,8 +216,13 @@ pub enum FileDragAndDrop {
 }
 
 /// An event that is sent when a window is repositioned in physical pixels.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Reflect, FromReflect)]
+#[reflect(Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serialize",
+    derive(serde::Serialize, serde::Deserialize),
+    reflect(Serialize, Deserialize)
+)]
 pub struct WindowMoved {
     pub id: WindowId,
     pub position: IVec2,

crates/bevy_window/src/lib.rs

@@ -24,6 +24,7 @@ pub mod prelude {
 
 use bevy_app::prelude::*;
 use bevy_ecs::schedule::{IntoSystemDescriptor, SystemLabel};
+use std::path::PathBuf;
 
 impl Default for WindowPlugin {
     fn default() -> Self {
@@ -97,6 +98,35 @@ impl Plugin for WindowPlugin {
         if self.close_when_requested {
             app.add_system(close_when_requested);
         }
+
+        // Register event types
+        app.register_type::<WindowResized>()
+            .register_type::<CreateWindow>()
+            .register_type::<RequestRedraw>()
+            .register_type::<WindowCreated>()
+            .register_type::<WindowCloseRequested>()
+            .register_type::<WindowClosed>()
+            .register_type::<CursorMoved>()
+            .register_type::<CursorEntered>()
+            .register_type::<CursorLeft>()
+            .register_type::<ReceivedCharacter>()
+            .register_type::<WindowFocused>()
+            .register_type::<WindowScaleFactorChanged>()
+            .register_type::<WindowBackendScaleFactorChanged>()
+            .register_type::<FileDragAndDrop>()
+            .register_type::<WindowMoved>();
+
+        // Register window descriptor and related types
+        app.register_type::<WindowId>()
+            .register_type::<PresentMode>()
+            .register_type::<WindowResizeConstraints>()
+            .register_type::<WindowMode>()
+            .register_type::<WindowPosition>()
+            .register_type::<MonitorSelection>()
+            .register_type::<WindowDescriptor>();
+
+        // Register `PathBuf` as it's used by `FileDragAndDrop`
+        app.register_type::<PathBuf>();
     }
 }