Merge webxr repository (#35228)

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/shared/webxr/events.rs

@@ -0,0 +1,80 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use euclid::RigidTransform3D;
+
+use crate::ApiSpace;
+use crate::BaseSpace;
+use crate::Frame;
+use crate::InputFrame;
+use crate::InputId;
+use crate::InputSource;
+use crate::SelectEvent;
+use crate::SelectKind;
+use crate::Sender;
+
+#[derive(Clone, Debug)]
+#[cfg_attr(feature = "ipc", derive(serde::Serialize, serde::Deserialize))]
+pub enum Event {
+    /// Input source connected
+    AddInput(InputSource),
+    /// Input source disconnected
+    RemoveInput(InputId),
+    /// Input updated (this is a disconnect+reconnect)
+    UpdateInput(InputId, InputSource),
+    /// Session ended by device
+    SessionEnd,
+    /// Session focused/blurred/etc
+    VisibilityChange(Visibility),
+    /// Selection started / ended
+    Select(InputId, SelectKind, SelectEvent, Frame),
+    /// Input from an input source has changed
+    InputChanged(InputId, InputFrame),
+    /// Reference space has changed
+    ReferenceSpaceChanged(BaseSpace, RigidTransform3D<f32, ApiSpace, ApiSpace>),
+}
+
+#[derive(Copy, Clone, Debug)]
+#[cfg_attr(feature = "ipc", derive(serde::Serialize, serde::Deserialize))]
+pub enum Visibility {
+    /// Session fully displayed to user
+    Visible,
+    /// Session still visible, but is not the primary focus
+    VisibleBlurred,
+    /// Session not visible
+    Hidden,
+}
+
+/// Convenience structure for buffering up events
+/// when no event callback has been set
+pub enum EventBuffer {
+    Buffered(Vec<Event>),
+    Sink(Sender<Event>),
+}
+
+impl Default for EventBuffer {
+    fn default() -> Self {
+        EventBuffer::Buffered(vec![])
+    }
+}
+
+impl EventBuffer {
+    pub fn callback(&mut self, event: Event) {
+        match *self {
+            EventBuffer::Buffered(ref mut events) => events.push(event),
+            EventBuffer::Sink(ref dest) => {
+                let _ = dest.send(event);
+            }
+        }
+    }
+
+    pub fn upgrade(&mut self, dest: Sender<Event>) {
+        if let EventBuffer::Buffered(ref mut events) = *self {
+            for event in events.drain(..) {
+                let _ = dest.send(event);
+            }
+        }
+        *self = EventBuffer::Sink(dest)
+    }
+}