Auto merge of #22528 - Manishearth:webxr, r=jdm,MortimerGoro

Preliminary WebXR support

This implements just enough WebXR to display to 3DOF devices in
immersive mode only.

Couple missing things:

 - [ ] Handling reference spaces (even if just supporting eye-level spaces)
 - [x] Spec links
 - [ ] We enter immersive mode when baseLayer is set, but it seems like
we're supposed to do this when requestSession is called (https://github.com/immersive-web/webxr/issues/453)
 - [ ] VR/XR should block less (https://github.com/servo/servo/issues/22505)
 - [x] More pref-gating
 - [x] `views` is a method instead of an attribute because we don't support FrozenArray

<s>Once I add spec links and pref gating</s> this can be landed as-is for further experimentation.

r? @jdm @MortimerGoro

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1 files changed, 67 insertions, 0 deletions

diff --git a/components/script/dom/xrframe.rs b/components/script/dom/xrframe.rs
new file mode 100644
index 00000000000..8343bb76420
--- /dev/null
+++ b/components/script/dom/xrframe.rs
@@ -0,0 +1,67 @@
+/* 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 crate::dom::bindings::codegen::Bindings::XRFrameBinding;
+use crate::dom::bindings::codegen::Bindings::XRFrameBinding::XRFrameMethods;
+use crate::dom::bindings::codegen::Bindings::XRViewBinding::XREye;
+use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
+use crate::dom::bindings::root::{Dom, DomRoot};
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::xrreferencespace::XRReferenceSpace;
+use crate::dom::xrsession::XRSession;
+use crate::dom::xrview::XRView;
+use crate::dom::xrviewerpose::XRViewerPose;
+use dom_struct::dom_struct;
+use webvr_traits::WebVRFrameData;
+
+#[dom_struct]
+pub struct XRFrame {
+    reflector_: Reflector,
+    session: Dom<XRSession>,
+    #[ignore_malloc_size_of = "defined in rust-webvr"]
+    data: WebVRFrameData,
+}
+
+impl XRFrame {
+    fn new_inherited(session: &XRSession, data: WebVRFrameData) -> XRFrame {
+        XRFrame {
+            reflector_: Reflector::new(),
+            session: Dom::from_ref(session),
+            data,
+        }
+    }
+
+    pub fn new(
+        global: &GlobalScope,
+        session: &XRSession,
+        data: WebVRFrameData,
+    ) -> DomRoot<XRFrame> {
+        reflect_dom_object(
+            Box::new(XRFrame::new_inherited(session, data)),
+            global,
+            XRFrameBinding::Wrap,
+        )
+    }
+}
+
+impl XRFrameMethods for XRFrame {
+    /// https://immersive-web.github.io/webxr/#dom-xrframe-session
+    fn Session(&self) -> DomRoot<XRSession> {
+        DomRoot::from_ref(&self.session)
+    }
+
+    /// https://immersive-web.github.io/webxr/#dom-xrframe-getviewerpose
+    fn GetViewerPose(&self, reference: Option<&XRReferenceSpace>) -> Option<DomRoot<XRViewerPose>> {
+        // We assume the reference space is eye level for now
+        // since it's the only one 3DOF devices support
+        if reference.is_some() {
+            // it's not possible to obtain a reference
+            // space at all yet
+            return None;
+        }
+        let left = XRView::new(&self.global(), &self.session, XREye::Left, &self.data);
+        let right = XRView::new(&self.global(), &self.session, XREye::Right, &self.data);
+        Some(XRViewerPose::new(&self.global(), &left, &right))
+    }
+}