Add XRHand interface

6 files changed, 115 insertions, 3 deletions

diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 97fffe52853..7a15870e917 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -157,8 +157,8 @@ use webgpu::{
     WebGPUPipelineLayout, WebGPUQueue, WebGPUShaderModule,
 };
 use webrender_api::{DocumentId, ImageKey};
-use webxr_api::Ray;
 use webxr_api::SwapChainId as WebXRSwapChainId;
+use webxr_api::{Finger, Hand, Ray};
 
 unsafe_no_jsmanaged_fields!(Tm);
 
@@ -881,6 +881,58 @@ where
     }
 }
 
+unsafe impl<J> JSTraceable for Hand<J>
+where
+    J: JSTraceable,
+{
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        // exhaustive match so we don't miss new fields
+        let Hand {
+            ref wrist,
+            ref thumb_metacarpal,
+            ref thumb_phalanx_proximal,
+            ref thumb_phalanx_distal,
+            ref thumb_phalanx_tip,
+            ref index,
+            ref middle,
+            ref ring,
+            ref little,
+        } = *self;
+        wrist.trace(trc);
+        thumb_metacarpal.trace(trc);
+        thumb_phalanx_proximal.trace(trc);
+        thumb_phalanx_distal.trace(trc);
+        thumb_phalanx_tip.trace(trc);
+        index.trace(trc);
+        middle.trace(trc);
+        ring.trace(trc);
+        little.trace(trc);
+    }
+}
+
+unsafe impl<J> JSTraceable for Finger<J>
+where
+    J: JSTraceable,
+{
+    #[inline]
+    unsafe fn trace(&self, trc: *mut JSTracer) {
+        // exhaustive match so we don't miss new fields
+        let Finger {
+            ref metacarpal,
+            ref phalanx_proximal,
+            ref phalanx_intermediate,
+            ref phalanx_distal,
+            ref phalanx_tip,
+        } = *self;
+        metacarpal.trace(trc);
+        phalanx_proximal.trace(trc);
+        phalanx_intermediate.trace(trc);
+        phalanx_distal.trace(trc);
+        phalanx_tip.trace(trc);
+    }
+}
+
 /// Holds a set of JSTraceables that need to be rooted
 struct RootedTraceableSet {
     set: Vec<*const dyn JSTraceable>,
diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index a410220b427..5c2ab978316 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -572,6 +572,7 @@ pub mod xmlhttprequesteventtarget;
 pub mod xmlhttprequestupload;
 pub mod xmlserializer;
 pub mod xrframe;
+pub mod xrhand;
 pub mod xrhittestresult;
 pub mod xrhittestsource;
 pub mod xrinputsource;
diff --git a/components/script/dom/webidls/XRHand.webidl b/components/script/dom/webidls/XRHand.webidl
new file mode 100644
index 00000000000..3bcbacbc329
--- /dev/null
+++ b/components/script/dom/webidls/XRHand.webidl
@@ -0,0 +1,10 @@
+/* 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/. */
+
+// https://github.com/immersive-web/webxr-hands-input/blob/master/explainer.md
+
+[SecureContext, Exposed=Window, Pref="dom.webxr.hands.enabled"]
+interface XRHand {
+//    getter XRJoint(unsigned short jointIndex);
+};
diff --git a/components/script/dom/webidls/XRInputSource.webidl b/components/script/dom/webidls/XRInputSource.webidl
index 487c959859d..b663666c872 100644
--- a/components/script/dom/webidls/XRInputSource.webidl
+++ b/components/script/dom/webidls/XRInputSource.webidl
@@ -24,4 +24,7 @@ interface XRInputSource {
   [SameObject] readonly attribute XRSpace? gripSpace;
   // [SameObject] readonly attribute Gamepad? gamepad;
   /* [SameObject] */ readonly attribute /* FrozenArray<DOMString> */ any profiles;
+
+  [Pref="dom.webxr.hands.enabled"]
+  readonly attribute XRHand? hand;
 };
diff --git a/components/script/dom/xrhand.rs b/components/script/dom/xrhand.rs
new file mode 100644
index 00000000000..a09966e3c75
--- /dev/null
+++ b/components/script/dom/xrhand.rs
@@ -0,0 +1,33 @@
+/* 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::reflector::{reflect_dom_object, Reflector};
+use crate::dom::bindings::root::{Dom, DomRoot};
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::xrinputsource::XRInputSource;
+use dom_struct::dom_struct;
+use webxr_api::Hand;
+
+#[dom_struct]
+pub struct XRHand {
+    reflector_: Reflector,
+    #[ignore_malloc_size_of = "defined in webxr"]
+    source: Dom<XRInputSource>,
+    #[ignore_malloc_size_of = "partially defind in webxr"]
+    support: Hand<()>,
+}
+
+impl XRHand {
+    fn new_inherited(source: &XRInputSource, support: Hand<()>) -> XRHand {
+        XRHand {
+            reflector_: Reflector::new(),
+            source: Dom::from_ref(source),
+            support,
+        }
+    }
+
+    pub fn new(global: &GlobalScope, source: &XRInputSource, support: Hand<()>) -> DomRoot<XRHand> {
+        reflect_dom_object(Box::new(XRHand::new_inherited(source, support)), global)
+    }
+}
diff --git a/components/script/dom/xrinputsource.rs b/components/script/dom/xrinputsource.rs
index ed8a3e6f1a5..bf9758f55a1 100644
--- a/components/script/dom/xrinputsource.rs
+++ b/components/script/dom/xrinputsource.rs
@@ -8,6 +8,7 @@ use crate::dom::bindings::codegen::Bindings::XRInputSourceBinding::{
 use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
 use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
 use crate::dom::globalscope::GlobalScope;
+use crate::dom::xrhand::XRHand;
 use crate::dom::xrsession::XRSession;
 use crate::dom::xrspace::XRSpace;
 use crate::realms::enter_realm;
@@ -24,10 +25,9 @@ pub struct XRInputSource {
     session: Dom<XRSession>,
     #[ignore_malloc_size_of = "Defined in rust-webxr"]
     info: InputSource,
-    #[ignore_malloc_size_of = "Defined in rust-webxr"]
     target_ray_space: MutNullableDom<XRSpace>,
-    #[ignore_malloc_size_of = "Defined in rust-webxr"]
     grip_space: MutNullableDom<XRSpace>,
+    hand: MutNullableDom<XRHand>,
     #[ignore_malloc_size_of = "mozjs"]
     profiles: Heap<JSVal>,
 }
@@ -40,6 +40,7 @@ impl XRInputSource {
             info,
             target_ray_space: Default::default(),
             grip_space: Default::default(),
+            hand: Default::default(),
             profiles: Heap::default(),
         }
     }
@@ -112,4 +113,16 @@ impl XRInputSourceMethods for XRInputSource {
     fn Profiles(&self, _cx: JSContext) -> JSVal {
         self.profiles.get()
     }
+
+    // https://github.com/immersive-web/webxr-hands-input/blob/master/explainer.md
+    fn GetHand(&self) -> Option<DomRoot<XRHand>> {
+        if let Some(ref hand) = self.info.hand_support {
+            Some(
+                self.hand
+                    .or_init(|| XRHand::new(&self.global(), &self, hand.clone())),
+            )
+        } else {
+            None
+        }
+    }
 }