Add basic support for window icons

crates/bevy_render/Cargo.toml

@@ -44,6 +44,7 @@ bevy_render_macros = { path = "macros", version = "0.11.0-dev" }
 bevy_time = { path = "../bevy_time", version = "0.11.0-dev" }
 bevy_transform = { path = "../bevy_transform", version = "0.11.0-dev" }
 bevy_window = { path = "../bevy_window", version = "0.11.0-dev" }
+bevy_winit = { path = "../bevy_winit", version = "0.11.0-dev" }
 bevy_utils = { path = "../bevy_utils", version = "0.11.0-dev" }
 bevy_tasks = { path = "../bevy_tasks", version = "0.11.0-dev" }
 
@@ -78,3 +79,4 @@ encase = { version = "0.5", features = ["glam"] }
 # For wgpu profiling using tracing. Use `RUST_LOG=info` to also capture the wgpu spans.
 profiling = { version = "1", features = ["profile-with-tracing"], optional = true }
 async-channel = "1.8"
+winit = { version = "0.28", default-features = false }

crates/bevy_render/src/texture/icon.rs

@@ -0,0 +1,76 @@
+use crate::texture::Image;
+use bevy_asset::{Assets, Handle};
+use bevy_ecs::{
+    prelude::{Component, Entity, NonSendMut, Query, Res},
+    system::Commands,
+};
+use bevy_log::{error, info};
+use bevy_winit::WinitWindows;
+use winit::window::Icon;
+
+/// An icon that can be placed at the top left of the window.
+#[derive(Component, Debug)]
+pub struct WindowIcon(pub Option<Handle<Image>>);
+
+/// Set or unset the window icon, depending on whether `Some(image_handle)` or `None` is provided.
+///
+/// # Example
+/// ```rust,no_run
+/// use bevy_app::{App, Startup, Update};
+/// use bevy_asset::AssetServer;
+/// use bevy_ecs::prelude::*;
+/// use bevy_render::texture::{set_window_icon, WindowIcon};
+///
+/// fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
+///     let icon_handle = asset_server.load("branding/icon.png");
+///     commands.spawn(WindowIcon(Some(icon_handle)));
+/// }
+///
+/// fn main() {
+///   App::new()
+///     .add_systems(Startup, setup)
+///     .add_systems(Update, set_window_icon)
+///     .run();
+/// }
+/// ```
+///
+/// This functionality [is only known to work on Windows and X11](https://docs.rs/winit/latest/winit/window/struct.Window.html#method.set_window_icon).
+pub fn set_window_icon(
+    images: Res<Assets<Image>>,
+    mut commands: Commands,
+    mut query: Query<(Entity, &mut WindowIcon)>,
+    mut winit_windows: NonSendMut<WinitWindows>,
+) {
+    for (entity, window_icon) in query.iter_mut() {
+        let icon = {
+            if let Some(image) = &window_icon.0 {
+                let Some(icon) = images.get(image) else { continue };
+                let result: Result<Icon, _> = icon.clone().try_into();
+
+                match result {
+                    Ok(icon) => Some(icon),
+                    Err(err) => {
+                        error!("failed to set window icon: {}", err);
+                        commands.entity(entity).remove::<WindowIcon>();
+                        continue;
+                    }
+                }
+            } else {
+                None
+            }
+        };
+
+        if let Some(icon) = &icon {
+            for (_id, window) in &mut winit_windows.windows {
+                window.set_window_icon(Some(icon.clone()));
+            }
+        } else {
+            for (_id, window) in &mut winit_windows.windows {
+                window.set_window_icon(None);
+            }
+        }
+
+        info!("window icon set");
+        commands.entity(entity).remove::<WindowIcon>();
+    }
+}

crates/bevy_render/src/texture/image.rs

@@ -11,11 +11,13 @@ use crate::{
     renderer::{RenderDevice, RenderQueue},
     texture::BevyDefault,
 };
+use anyhow::anyhow;
 use bevy_asset::HandleUntyped;
 use bevy_derive::{Deref, DerefMut};
 use bevy_ecs::system::{lifetimeless::SRes, Resource, SystemParamItem};
 use bevy_math::Vec2;
 use bevy_reflect::{FromReflect, Reflect, TypeUuid};
+use winit::window::Icon;
 
 use std::hash::Hash;
 use thiserror::Error;
@@ -613,6 +615,23 @@ impl CompressedImageFormats {
     }
 }
 
+// Convert an [`Image`] to `winit::window::Icon`.
+impl TryInto<Icon> for Image {
+    type Error = anyhow::Error;
+
+    fn try_into(self) -> Result<Icon, Self::Error> {
+        let Ok(icon) = self.try_into_dynamic() else {
+            return Err(anyhow!("failed to convert Image to DynamicImage"));
+        };
+
+        let width = icon.width();
+        let height = icon.height();
+        let data = icon.into_rgba8().into_raw();
+        Icon::from_rgba(data, width, height)
+            .map_err(|err| anyhow!("failed to convert image to winit::window::Icon: {}", err))
+    }
+}
+
 #[cfg(test)]
 mod test {
 

crates/bevy_render/src/texture/mod.rs

@@ -7,6 +7,7 @@ mod exr_texture_loader;
 mod fallback_image;
 #[cfg(feature = "hdr")]
 mod hdr_texture_loader;
+pub mod icon;
 #[allow(clippy::module_inception)]
 mod image;
 mod image_texture_loader;
@@ -27,6 +28,7 @@ pub use exr_texture_loader::*;
 pub use hdr_texture_loader::*;
 
 pub use fallback_image::*;
+pub use icon::*;
 pub use image_texture_loader::*;
 pub use texture_cache::*;
 

examples/window/window_settings.rs

@@ -4,6 +4,7 @@
 use bevy::{
     diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
     prelude::*,
+    render::texture::{set_window_icon, WindowIcon},
     window::{CursorGrabMode, PresentMode, WindowLevel},
 };
 
@@ -24,9 +25,11 @@ fn main() {
         }))
         .add_plugin(LogDiagnosticsPlugin::default())
         .add_plugin(FrameTimeDiagnosticsPlugin)
+        .add_systems(Startup, setup)
         .add_systems(
             Update,
             (
+                set_window_icon,
                 change_title,
                 toggle_cursor,
                 toggle_vsync,
@@ -37,6 +40,12 @@ fn main() {
         .run();
 }
 
+/// Add an icon to the window task bar.  Only works in Windows and Linux.
+fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
+    let icon_handle = asset_server.load("branding/icon.png");
+    commands.spawn(WindowIcon(Some(icon_handle)));
+}
+
 /// This system toggles the vsync mode when pressing the button V.
 /// You'll see fps increase displayed in the console.
 fn toggle_vsync(input: Res<Input<KeyCode>>, mut windows: Query<&mut Window>) {