Desktop: Custom cursor support (#3452)

custom cursors with caching

desktop/src/window.rs

@@ -1,4 +1,6 @@
+use std::collections::HashMap;
 use std::sync::Arc;
+use winit::cursor::{CursorIcon, CustomCursor, CustomCursorSource};
 use winit::event_loop::ActiveEventLoop;
 use winit::window::{Window as WinitWindow, WindowAttributes};
 
@@ -35,6 +37,7 @@ pub(crate) struct Window {
 	winit_window: Arc<dyn winit::window::Window>,
 	#[allow(dead_code)]
 	native_handle: native::NativeWindowImpl,
+	custom_cursors: HashMap<CustomCursorSource, CustomCursor>,
 }
 
 impl Window {
@@ -57,6 +60,7 @@ impl Window {
 		Self {
 			winit_window: winit_window.into(),
 			native_handle,
+			custom_cursors: HashMap::new(),
 		}
 	}
 
@@ -108,7 +112,24 @@ impl Window {
 		self.native_handle.show_all();
 	}
 
-	pub(crate) fn set_cursor(&self, cursor: winit::cursor::Cursor) {
+	pub(crate) fn set_cursor(&mut self, event_loop: &dyn ActiveEventLoop, cursor: Cursor) {
+		let cursor = match cursor {
+			Cursor::Icon(cursor_icon) => cursor_icon.into(),
+			Cursor::Custom(custom_cursor_source) => {
+				let custom_cursor = match self.custom_cursors.get(&custom_cursor_source).cloned() {
+					Some(cursor) => cursor,
+					None => {
+						let Ok(custom_cursor) = event_loop.create_custom_cursor(custom_cursor_source.clone()) else {
+							tracing::error!("Failed to create custom cursor");
+							return;
+						};
+						self.custom_cursors.insert(custom_cursor_source, custom_cursor.clone());
+						custom_cursor
+					}
+				};
+				custom_cursor.into()
+			}
+		};
 		self.winit_window.set_cursor(cursor);
 	}
 
@@ -116,3 +137,18 @@ impl Window {
 		self.native_handle.update_menu(entries);
 	}
 }
+
+pub(crate) enum Cursor {
+	Icon(CursorIcon),
+	Custom(CustomCursorSource),
+}
+impl From<CursorIcon> for Cursor {
+	fn from(icon: CursorIcon) -> Self {
+		Cursor::Icon(icon)
+	}
+}
+impl From<CustomCursorSource> for Cursor {
+	fn from(custom: CustomCursorSource) -> Self {
+		Cursor::Custom(custom)
+	}
+}