Feature/backend openxr pollevent (#513)

* Backend OpenXR PollEvent API in C layer * Backend OpenXR PollEvent API in C# layer * Add context as first callback argument
StereoKit · Nov 10, 2022 · c2f09f2 · c2f09f2
1 parent 0b73692
commit c2f09f2
Show file tree

Hide file tree

Showing 6 changed files with 92 additions and 2 deletions.
diff --git a/StereoKit/Native/NativeAPI.cs b/StereoKit/Native/NativeAPI.cs
@@ -536,6 +536,8 @@ internal static class NativeAPI
 		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern void          backend_openxr_use_minimum_exts(int use_minimum_exts);
 		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern void          backend_openxr_composition_layer(IntPtr XrCompositionLayerBaseHeader, int layer_size, int sort_order);
 		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern void          backend_openxr_add_callback_pre_session_create([MarshalAs(UnmanagedType.FunctionPtr)] XRPreSessionCreateCallback on_pre_session_create, IntPtr context);
+		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern void          backend_openxr_add_callback_poll_event        ([MarshalAs(UnmanagedType.FunctionPtr)] XRPollEventCallback on_poll_event, IntPtr context);
+		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern void          backend_openxr_remove_callback_poll_event     ([MarshalAs(UnmanagedType.FunctionPtr)] XRPollEventCallback on_poll_event);
 		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern BackendPlatform backend_platform_get        ();
 		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern IntPtr          backend_android_get_java_vm ();
 		[DllImport(dll, CharSet = cSet, CallingConvention = call)] public static extern IntPtr          backend_android_get_activity();

diff --git a/StereoKit/Native/NativeTypes.cs b/StereoKit/Native/NativeTypes.cs
@@ -393,6 +393,9 @@ public Ray Ray
 	[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
 	internal delegate void XRPreSessionCreateCallback(IntPtr context);
 
+	[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+	internal delegate void XRPollEventCallback(IntPtr context, IntPtr XrEventDataBuffer);
+
 	[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
 	internal delegate void AssetOnLoadCallback(IntPtr asset, IntPtr context);
 

diff --git a/StereoKit/Systems/Backend.cs b/StereoKit/Systems/Backend.cs
@@ -1,4 +1,5 @@
-using System;
+using System;
+using System.Collections.Generic;
 using System.Runtime.InteropServices;
 
 namespace StereoKit
@@ -169,6 +170,38 @@ internal static void CleanupInitialize()
 				_onPreCreateSession           = null;
 				_onPreCreateSessionRegistered = false;
 			}
+
+			private struct XRPollEventCallbackData
+			{
+				public Action<IntPtr>      action;
+				public XRPollEventCallback callback;
+			}
+
+			private static List<XRPollEventCallbackData> _xrPollEventCallbacks;
+
+			/// <summary>This event gets published each time xrPollEvent results in XR_SUCCESS.</summary>
+			public static event Action<IntPtr> OnPollEvent
+			{
+				add
+				{
+					if (_xrPollEventCallbacks == null) _xrPollEventCallbacks = new List<XRPollEventCallbackData>();
+
+					XRPollEventCallback callback = (_, XrEventDataBuffer) => { value(XrEventDataBuffer); };
+					_xrPollEventCallbacks.Add(new XRPollEventCallbackData { action = value, callback = callback });
+
+					NativeAPI.backend_openxr_add_callback_poll_event(callback, IntPtr.Zero);
+				}
+				remove
+				{
+					if (_xrPollEventCallbacks == null) throw new NullReferenceException();
+
+					int i = _xrPollEventCallbacks.FindIndex(d => d.action == value);
+					if (i < 0) throw new KeyNotFoundException();
+
+					NativeAPI.backend_openxr_remove_callback_poll_event(_xrPollEventCallbacks[i].callback);
+					_xrPollEventCallbacks.RemoveAt(i);
+				}
+			}
 		}
 
 		/// <summary>This class contains variables that may be useful for

diff --git a/StereoKitC/backend.cpp b/StereoKitC/backend.cpp
@@ -106,6 +106,18 @@ void backend_openxr_add_callback_pre_session_create(void (*on_pre_session_create
 
 ///////////////////////////////////////////
 
+void backend_openxr_add_callback_poll_event(void (*on_poll_event)(void* context, void* XrEventDataBuffer), void* context) {
+	log_err(backend_err_wrong_backend);
+}
+
+///////////////////////////////////////////
+
+void backend_openxr_remove_callback_poll_event(void (*on_poll_event)(void* context, void* XrEventDataBuffer)) {
+	log_err(backend_err_wrong_backend);
+}
+
+///////////////////////////////////////////
+
 void backend_openxr_composition_layer(void *XrCompositionLayerBaseHeader, int32_t layer_size, int32_t sort_order) {
 	log_err(backend_err_wrong_backend);
 }

diff --git a/StereoKitC/stereokit.h b/StereoKitC/stereokit.h
@@ -2005,6 +2005,8 @@ SK_API void              backend_openxr_use_minimum_exts    (bool32_t use_minimu
 SK_API void              backend_openxr_composition_layer   (void *XrCompositionLayerBaseHeader, int32_t layer_size, int32_t sort_order);
 
 SK_API void              backend_openxr_add_callback_pre_session_create(void (*on_pre_session_create)(void* context), void* context);
+SK_API void              backend_openxr_add_callback_poll_event        (void (*on_poll_event)(void* context, void* XrEventDataBuffer), void* context);
+SK_API void              backend_openxr_remove_callback_poll_event     (void (*on_poll_event)(void* context, void* XrEventDataBuffer));
 
 SK_API backend_platform_ backend_platform_get         ();
 SK_API void             *backend_android_get_java_vm  ();

diff --git a/StereoKitC/xr_backends/openxr.cpp b/StereoKitC/xr_backends/openxr.cpp
@@ -45,6 +45,11 @@ typedef struct context_callback_t {
 	void *context;
 } context_callback_t;
 
+typedef struct poll_event_callback_t {
+	void (*callback)(void* context, void* XrEventDataBuffer);
+	void *context;
+} poll_event_callback_t;
+
 XrFormFactor xr_config_form = XR_FORM_FACTOR_HEAD_MOUNTED_DISPLAY;
 const char *xr_request_layers[] = {
 	"",
@@ -71,7 +76,8 @@ array_t<const char*> xr_exts_user    = {};
 array_t<uint64_t>    xr_exts_loaded  = {};
 bool32_t             xr_minimum_exts = false;
 
-array_t<context_callback_t> xr_callbacks_pre_session_create = {};
+array_t<context_callback_t>    xr_callbacks_pre_session_create = {};
+array_t<poll_event_callback_t> xr_callbacks_poll_event         = {};
 
 bool   xr_has_bounds        = false;
 vec2   xr_bounds_size       = {};
@@ -697,6 +703,11 @@ void openxr_poll_events() {
 			break;
 		default: break;
 		}
+
+		for (int32_t i = 0; i < xr_callbacks_poll_event.count; i++) {
+			xr_callbacks_poll_event[i].callback(xr_callbacks_poll_event[i].context, &event_buffer);
+		}
+
 		event_buffer = { XR_TYPE_EVENT_DATA_BUFFER };
 	}
 }
@@ -1016,6 +1027,33 @@ void backend_openxr_add_callback_pre_session_create(void (*on_pre_session_create
 	xr_callbacks_pre_session_create.add({ on_pre_session_create, context });
 }
 
+///////////////////////////////////////////
+
+void backend_openxr_add_callback_poll_event(void (*on_poll_event)(void* context, void* XrEventDataBuffer), void* context) {
+	if (backend_xr_get_type() != backend_xr_type_openxr) {
+		log_err("backend_openxr_ functions only work when OpenXR is the backend!");
+		return;
+	}
+
+	xr_callbacks_poll_event.add({ on_poll_event, context });
+}
+
+///////////////////////////////////////////
+
+void backend_openxr_remove_callback_poll_event(void (*on_poll_event)(void* context, void* XrEventDataBuffer)) {
+	if (backend_xr_get_type() != backend_xr_type_openxr) {
+		log_err("backend_openxr_ functions only work when OpenXR is the backend!");
+		return;
+	}
+
+	for (int32_t i = 0; i < xr_callbacks_poll_event.count; i++) {
+		if (xr_callbacks_poll_event[i].callback == on_poll_event || on_poll_event == nullptr) {
+			xr_callbacks_poll_event.remove(i);
+			return;
+		}
+	}
+}
+
 } // namespace sk
 
 #endif