Web: improve custom cursor loading (#3321)

src/platform_impl/web/event_loop/runner.rs

@@ -1,3 +1,4 @@
+use super::super::cursor::CustomCursorHandle;
 use super::super::main_thread::MainThreadMarker;
 use super::super::DeviceId;
 use super::{backend, state::State};
@@ -139,6 +140,16 @@ impl Runner {
                     )
                 }
             }
+            EventWrapper::CursorReady(result) => {
+                for (_, canvas, _) in runner.0.all_canvases.borrow().deref() {
+                    if let Some(canvas) = canvas.upgrade() {
+                        canvas
+                            .borrow_mut()
+                            .cursor
+                            .handle_cursor_ready(result.clone())
+                    }
+                }
+            }
         }
     }
 }
@@ -811,6 +822,19 @@ impl Shared {
     pub(crate) fn waker(&self) -> Waker<Weak<Execution>> {
         self.0.proxy_spawner.waker()
     }
+
+    pub(crate) fn weak(&self) -> WeakShared {
+        WeakShared(Rc::downgrade(&self.0))
+    }
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct WeakShared(Weak<Execution>);
+
+impl WeakShared {
+    pub(crate) fn upgrade(&self) -> Option<Shared> {
+        self.0.upgrade().map(Shared)
+    }
 }
 
 pub(crate) enum EventWrapper {
@@ -820,6 +844,7 @@ pub(crate) enum EventWrapper {
         size: PhysicalSize<u32>,
         scale: f64,
     },
+    CursorReady(Result<CustomCursorHandle, CustomCursorHandle>),
 }
 
 impl From<Event<()>> for EventWrapper {