Index: trunk/src/hid_helper.c
===================================================================
--- trunk/src/hid_helper.c	(revision 18264)
+++ trunk/src/hid_helper.c	(revision 18265)
@@ -288,7 +288,7 @@
 	return -1;
 }
 
-void pcb_cam_end(pcb_cam_t *dst)
+int pcb_cam_end(pcb_cam_t *dst)
 {
 	free(dst->inst);
 	dst->inst = NULL;
@@ -296,6 +296,7 @@
 		return;
 	layervis_restore(dst);
 	dst->active = 0;
+	return dst->exported_grps;
 }
 
 
@@ -316,9 +317,11 @@
 	}
 	else {
 		int vid = vl->new_id - PCB_LYT_VIRTUAL - 1;
-		return !cam->vgrp_vis[vid];
+		if (!cam->vgrp_vis[vid])
+			return 1;
 	}
 
+	cam->exported_grps++;
 	return 0;
 }
 
Index: trunk/src/hid_helper.h
===================================================================
--- trunk/src/hid_helper.h	(revision 18264)
+++ trunk/src/hid_helper.h	(revision 18265)
@@ -34,12 +34,16 @@
 	char *inst;
 	pcb_board_t *pcb;
 	int orig_vis[PCB_MAX_LAYER]; /* backup of the original layer visibility */
+	int exported_grps;
 } pcb_cam_t;
 
 int pcb_cam_begin(pcb_board_t *pcb, pcb_cam_t *dst, const char *src, const pcb_hid_attribute_t *attr_tbl, int numa, pcb_hid_attr_val_t *options);
-void pcb_cam_end(pcb_cam_t *dst);
 
+/* Finish cam export, free all memory, mark cam export inactive and report
+   the number of layer groups exported */
+int pcb_cam_end(pcb_cam_t *dst);
 
+
 /* Shall be the first rule in a cam capable exporter's set_layer_group()
    callback: decides not to draw a layer group in cam mode if the
    group is not scheduled for export */