Bug 1655006 - Implement WebXR nativeFramebufferScaleFactor. r=jgilbert,kip,daoshengmu

Clamp the requested XRWebGLLayer framebuffer size to ensure it's not too small to see or larger than the max native resolution.

Differential Revision: https://phabricator.services.mozilla.com/D84799

dom/canvas/XRWebGLLayer.cpp

@@ -24,6 +24,8 @@ using namespace mozilla::gl;
 namespace mozilla {
 namespace dom {
 
+static constexpr float XR_FRAMEBUFFER_MIN_SCALE = 0.2f;
+
 NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(XRWebGLLayer, mParent, mSession, mWebGL,
                                       mFramebuffer, mLeftViewport,
                                       mRightViewport)
@@ -136,12 +138,19 @@ already_AddRefed<XRWebGLLayer> XRWebGLLayer::Constructor(
     options.depthStencil =
         aXRWebGLLayerInitDict.mDepth || aXRWebGLLayerInitDict.mStencil;
 
+    // Clamp the requested framebuffer size to ensure it's not too
+    // small to see or larger than the max native resolution.
+    const float maxScale =
+        std::max(displayState.nativeFramebufferScaleFactor, 1.0f);
     const float scaleFactor =
-        fmin(aXRWebGLLayerInitDict.mFramebufferScaleFactor, 1.0f);
+        std::max(XR_FRAMEBUFFER_MIN_SCALE,
+                 std::min((float)aXRWebGLLayerInitDict.mFramebufferScaleFactor,
+                          maxScale));
 
     options.width =
-        (int32_t)(2.0f * displayState.eyeResolution.width * scaleFactor);
-    options.height = (int32_t)(displayState.eyeResolution.height * scaleFactor);
+        (int32_t)ceilf(2.0f * displayState.eyeResolution.width * scaleFactor);
+    options.height =
+        (int32_t)ceilf(displayState.eyeResolution.height * scaleFactor);
     framebuffer = gl->CreateOpaqueFramebuffer(options);
 
     if (!framebuffer) {
@@ -233,14 +242,19 @@ already_AddRefed<XRViewport> XRWebGLLayer::GetViewport(const XRView& aView) {
   return result.forget();
 }
 
+// https://www.w3.org/TR/webxr/#dom-xrwebgllayer-getnativeframebufferscalefactor
 /* static */ double XRWebGLLayer::GetNativeFramebufferScaleFactor(
     const GlobalObject& aGlobal, const XRSession& aSession) {
   if (aSession.IsEnded()) {
     return 0.0f;
   }
-  // TODO: Get the maximum framebuffer size from each display.
-  // Right now we assume that the recommended size is the maximum one.
-  return 1.0f;
+  if (!aSession.IsImmersive()) {
+    return 1.0f;
+  }
+
+  const gfx::VRDisplayInfo& displayInfo =
+      aSession.GetDisplayClient()->GetDisplayInfo();
+  return displayInfo.mDisplayState.nativeFramebufferScaleFactor;
 }
 
 void XRWebGLLayer::StartAnimationFrame() {

dom/vr/XRSession.cpp

@@ -143,7 +143,9 @@ XRSession::XRSession(
 
 XRSession::~XRSession() { MOZ_ASSERT(mShutdown); }
 
-gfx::VRDisplayClient* XRSession::GetDisplayClient() { return mDisplayClient; }
+gfx::VRDisplayClient* XRSession::GetDisplayClient() const {
+  return mDisplayClient;
+}
 
 JSObject* XRSession::WrapObject(JSContext* aCx,
                                 JS::Handle<JSObject*> aGivenProto) {
@@ -382,7 +384,9 @@ already_AddRefed<Promise> XRSession::RequestReferenceSpace(
   return promise.forget();
 }
 
-XRRenderState* XRSession::GetActiveRenderState() { return mActiveRenderState; }
+XRRenderState* XRSession::GetActiveRenderState() const {
+  return mActiveRenderState;
+}
 
 void XRSession::XRFrameRequest::Call(const DOMHighResTimeStamp& aTimeStamp,
                                      XRFrame& aFrame) {

dom/vr/XRSession.h

@@ -87,8 +87,8 @@ class XRSession final : public DOMEventTargetHelper, public nsARefreshObserver {
   IMPL_EVENT_HANDLER(visibilitychange);
 
   // Non WebIDL Members
-  gfx::VRDisplayClient* GetDisplayClient();
-  XRRenderState* GetActiveRenderState();
+  gfx::VRDisplayClient* GetDisplayClient() const;
+  XRRenderState* GetActiveRenderState() const;
   bool IsEnded() const;
   bool IsImmersive() const;
   MOZ_CAN_RUN_SCRIPT

gfx/vr/external_api/moz_external_vr.h

@@ -47,8 +47,8 @@ namespace gfx {
 // and mapped files if we have both release and nightlies
 // running at the same time? Or...what if we have multiple
 // release builds running on same machine? (Bug 1563232)
-#define SHMEM_VERSION "0.0.10"
-static const int32_t kVRExternalVersion = 17;
+#define SHMEM_VERSION "0.0.11"
+static const int32_t kVRExternalVersion = 18;
 
 // We assign VR presentations to groups with a bitmask.
 // Currently, we will only display either content or chrome.
@@ -345,6 +345,7 @@ struct VRDisplayState {
   VRFieldOfView eyeFOV[VRDisplayState::NumEyes];
   Point3D_POD eyeTranslation[VRDisplayState::NumEyes];
   IntSize_POD eyeResolution;
+  float nativeFramebufferScaleFactor;
   bool suppressFrames;
   bool isConnected;
   bool isMounted;

gfx/vr/service/OculusSession.cpp

@@ -1054,6 +1054,7 @@ bool OculusSession::InitState(VRSystemState& aSystemState) {
                                        texSize[VRDisplayState::Eye_Right].w);
   state.eyeResolution.height = std::max(texSize[VRDisplayState::Eye_Left].h,
                                         texSize[VRDisplayState::Eye_Right].h);
+  state.nativeFramebufferScaleFactor = 1.0f;
 
   // default to an identity quaternion
   aSystemState.sensorState.pose.orientation[3] = 1.0f;

gfx/vr/service/OpenVRSession.cpp

@@ -740,6 +740,7 @@ bool OpenVRSession::InitState(VRSystemState& aSystemState) {
   mVRSystem->GetRecommendedRenderTargetSize(&w, &h);
   state.eyeResolution.width = w;
   state.eyeResolution.height = h;
+  state.nativeFramebufferScaleFactor = 1.0f;
 
   // default to an identity quaternion
   aSystemState.sensorState.pose.orientation[3] = 1.0f;