st/prober: Improve usage of SLAM tracking frameservers

Use a similar "hardcoded" idea as in p_factory_ensure_frameserver.
This fix usage of SLAM sources in other contexts like calibration, at the
cost of requiring a device to call create_tracked_slam at least once.
(again, similar to how psmv/psvr/hand tracking work already)

src/xrt/drivers/euroc/euroc_device.c

@@ -251,18 +251,17 @@ euroc_device_create(struct xrt_prober *xp)
 		xd->get_view_pose = euroc_get_view_pose;
 	}
 
-	int ret = xp->tracking->create_tracked_slam(xp->tracking, xd, &ed->slam);
-	if (ret < 0) {
-		EUROC_WARN(ed,
-		           "Unable to create the SLAM tracker so the Euroc device won't be tracked.\n\t"
-		           "Did you provide the appropriate SLAM dependency when compiling?");
-		// However, we can continue, maybe the user just wants to play with the euroc utilities
-	}
-
 	u_var_add_root(ed, dev_name, false);
 	u_var_add_pose(ed, &ed->pose, "pose");
 	u_var_add_pose(ed, &ed->offset, "offset");
 	u_var_add_pose(ed, &ed->tracking_origin.offset, "tracking offset");
 
+	bool tracked = xp->tracking->create_tracked_slam(xp->tracking, xd, &ed->slam) >= 0;
+	if (!tracked) {
+		EUROC_WARN(ed, "Unable to setup the SLAM tracker");
+		euroc_device_destroy(xd);
+		return NULL;
+	}
+
 	return xd;
 }

src/xrt/state_trackers/prober/p_prober.c

@@ -977,15 +977,6 @@ p_open_video_device(struct xrt_prober *xp,
 
 	XRT_MAYBE_UNUSED struct prober_device *pdev = (struct prober_device *)xpdev;
 
-#if defined(XRT_BUILD_DRIVER_EUROC)
-	// TODO: If both VF_PATH and EUROC_PATH are set, VF will be ignored on calibration
-	const char *euroc_path = debug_get_option_euroc_path();
-	if (euroc_path != NULL) {
-		*out_xfs = euroc_player_create(xfctx, euroc_path); // Euroc will exit if it can't be created
-		return 0;
-	}
-#endif
-
 #if defined(XRT_BUILD_DRIVER_VF)
 	const char *path = debug_get_option_vf_path();
 	if (path != NULL) {
@@ -997,6 +988,14 @@ p_open_video_device(struct xrt_prober *xp,
 	}
 #endif
 
+#if defined(XRT_BUILD_DRIVER_EUROC)
+	const char *euroc_path = debug_get_option_euroc_path();
+	if (euroc_path != NULL) {
+		*out_xfs = euroc_player_create(xfctx, euroc_path); // Euroc will exit if it can't be created
+		return 0;
+	}
+#endif
+
 #if defined(XRT_HAVE_V4L2)
 	if (pdev->num_v4ls == 0) {
 		return -1;
@@ -1020,17 +1019,17 @@ p_list_video_devices(struct xrt_prober *xp, xrt_prober_list_video_cb cb, void *p
 {
 	struct prober *p = (struct prober *)xp;
 
-	const char *path = debug_get_option_vf_path();
-	if (path != NULL) {
-		cb(xp, NULL, "Video File", "Collabora", path, ptr);
+	// Video sources from drivers (at most one will be listed)
+	const char *vf_path = debug_get_option_vf_path();
+	const char *euroc_path = debug_get_option_euroc_path();
+
+	if (vf_path != NULL) {
+		cb(xp, NULL, "Video File", "Collabora", vf_path, ptr);
+	} else if (euroc_path != NULL) {
+		cb(xp, NULL, "Euroc Dataset", "Collabora", euroc_path, ptr);
 	}
 
-	path = debug_get_option_euroc_path();
-	if (path != NULL) {
-		cb(xp, NULL, "Euroc Dataset", "Collabora", path, ptr);
-	}
-
-	// Loop over all devices and find video devices.
+	// Video sources from video devices
 	for (size_t i = 0; i < p->num_devices; i++) {
 		struct prober_device *pdev = &p->devices[i];
 

src/xrt/state_trackers/prober/p_tracking.c

@@ -234,6 +234,47 @@ p_factory_ensure_frameserver(struct p_factory *fact)
 	// Start the stream now.
 	xrt_fs_stream_start(fact->xfs, xsink, XRT_FS_CAPTURE_TYPE_TRACKING, fact->settings.camera_mode);
 }
+
+//! @todo Similar to p_factory_ensure_frameserver but for SLAM sources.
+//! Therefore we can only have one SLAM tracker at a time, with exactly one SLAM
+//! tracked device. It would be good to solve these artificial restrictions.
+static bool
+p_factory_ensure_slam_frameserver(struct p_factory *fact)
+{
+	// Factory frameserver is already in use
+	if (fact->xfs != NULL) {
+		return false;
+	}
+
+	// SLAM tracker with EuRoC frameserver
+
+#ifdef XRT_BUILD_DRIVER_EUROC
+	if (debug_get_option_euroc_path() != NULL) {
+		struct xrt_slam_sinks empty_sinks = {0};
+		struct xrt_slam_sinks *sinks = &empty_sinks;
+
+		xrt_prober_open_video_device(&fact->p->base, NULL, &fact->xfctx, &fact->xfs);
+		assert(fact->xfs->source_id == 0xECD0FEED && "xfs is not Euroc, unsynced open_video_device?");
+
+#ifdef XRT_HAVE_SLAM
+		int ret = t_slam_create(&fact->xfctx, &fact->xts, &sinks);
+		if (ret != 0) {
+			U_LOG_W("Unable to initialize SLAM tracking, the Euroc driver will not be tracked");
+		}
+#else
+		U_LOG_W("SLAM tracking support is disabled, the Euroc driver will not be tracked");
+#endif
+
+		xrt_fs_slam_stream_start(fact->xfs, sinks);
+
+		return true;
+	}
+#endif
+
+	// No SLAM sources were started
+	return false;
+}
+
 #endif
 
 
@@ -344,15 +385,7 @@ p_factory_create_tracked_slam(struct xrt_tracking_factory *xfact,
 
 	struct xrt_tracked_slam *xts = NULL;
 
-#ifdef XRT_BUILD_DRIVER_EUROC
-	if (debug_get_option_euroc_path() != NULL) {
-		// The euroc slam tracker was already created on p_tracking_init because the
-		// euroc player is not a device so it needs to be started from somewhere
-		goto end;
-	}
-#endif
-
-end:
+	p_factory_ensure_slam_frameserver(fact);
 
 	if (!fact->started_xts) {
 		xts = fact->xts;
@@ -372,6 +405,7 @@ end:
 #endif
 }
 
+
 /*
  *
  * "Exported" prober functions.
@@ -402,27 +436,6 @@ p_tracking_init(struct prober *p)
 	// Finally set us as the tracking factory.
 	p->base.tracking = &fact->base;
 
-#ifdef XRT_BUILD_DRIVER_EUROC
-	if (debug_get_option_euroc_path() != NULL) {
-		struct xrt_slam_sinks empty_sinks = {0};
-		struct xrt_slam_sinks *sinks = &empty_sinks;
-
-		// fact->xfs *will* be an euroc frame server after open, because of prober open_video_device
-		xrt_prober_open_video_device(&fact->p->base, NULL, &fact->xfctx, &fact->xfs);
-
-#ifdef XRT_HAVE_SLAM
-		int ret = t_slam_create(&fact->xfctx, &fact->xts, &sinks);
-		if (ret != 0) {
-			U_LOG_W("Unable to initialize SLAM tracking, the Euroc driver will not be tracked");
-		}
-#else
-		U_LOG_W("SLAM tracking support is disabled, the Euroc driver will not be tracked");
-#endif
-
-		xrt_fs_slam_stream_start(fact->xfs, sinks);
-	}
-#endif
-
 	return 0;
 }