xrEnumerateInstanceExtensionProperties.cpp

XrResult OXRTracing_xrEnumerateInstanceExtensionProperties(
    const char* layerName, uint32_t propertyCapacityInput,
    uint32_t* propertyCountOutput, XrExtensionProperties* properties)
{
	TraceLoggingActivity<gTraceProvider> localActivity;
	TraceLoggingWriteStart(localActivity,
	    "xrEnumerateInstanceExtensionProperties",
	    TraceLoggingString(layerName, "layerName"),
	    TraceLoggingUInt32(propertyCapacityInput, "propertyCapacityInput"));

	// The OpenXR specification says that this should work without an instance,
	// however, a 'next' pointer is needed to query extensions that might be
	// provided by another API layer, and the OpenXR *Loader* spec says:
	//
	// "an implicit API layer, it must add it’s own instance extension
	// contents to the list of extensions."; this means we - and any lower
	// layers - need the 'next' pointer, which can vary by instance

	if (layerName == NULL && gXrNextEnumerateInstanceExtensionProperties) {
		const auto ret = gXrNextEnumerateInstanceExtensionProperties(
		    layerName, propertyCapacityInput, propertyCountOutput, properties);

		if (XR_SUCCEEDED(ret)) {
			const auto propertyCount
		    	= std::min(propertyCapacityInput, *propertyCountOutput);
	
			for (auto i = 0; i < propertyCount; ++i) {
				OXRTL_DUMP_XrExtensionProperties(localActivity,
				    "xrEnumerateInstanceExtensionProperties", "properties[]",
				    (properties[i]));
			}
		}

		TraceLoggingWriteStop(localActivity,
		    "xrEnumerateInstanceExtensionProperties",
		    TraceLoggingUInt32(*propertyCountOutput, "propertyCountOutput"),
		    OXRTL_ARGS_XrResult(ret, "XrResult"));
		return ret;
	}
	*propertyCountOutput = 0;
	TraceLoggingWriteStop(localActivity,
	    "xrEnumerateInstanceExtensionProperties",
	    TraceLoggingUInt32(0, "propertyCountOutput"),
	    OXRTL_ARGS_XrResult(XR_SUCCESS, "XrResult"));
	return XR_SUCCESS;
}