Refresh the _depth_units when its changed.

src/ds5/ds5-device.cpp

@@ -168,6 +168,8 @@ namespace librealsense
 
         float get_depth_scale() const override { return _depth_units; }
 
+        void set_depth_scale(float val){ _depth_units = val; }
+
         float get_stereo_baseline_mm() const override { return _owner->get_stereo_baseline_mm(); }
 
         void create_snapshot(std::shared_ptr<depth_sensor>& snapshot) const
@@ -191,7 +193,7 @@ namespace librealsense
         }
     protected:
         const ds5_device* _owner;
-        float _depth_units;
+        std::atomic<float> _depth_units;
         float _stereo_baseline_mm;
     };
 
@@ -476,7 +478,18 @@ namespace librealsense
             lazy<float>([this]() { return get_stereo_baseline_mm(); })));
 
         if (advanced_mode && _fw_version >= firmware_version("5.6.3.0"))
-            depth_ep.register_option(RS2_OPTION_DEPTH_UNITS, std::make_shared<depth_scale_option>(*_hw_monitor));
+        {
+            auto depth_scale = std::make_shared<depth_scale_option>(*_hw_monitor);
+            auto depth_sensor = As<ds5_depth_sensor, uvc_sensor>(&depth_ep);
+            assert(depth_sensor);
+
+            depth_scale->add_observer([depth_sensor](float val)
+            {
+                depth_sensor->set_depth_scale(val);  
+            });
+
+            depth_ep.register_option(RS2_OPTION_DEPTH_UNITS, depth_scale);
+        }
         else
             depth_ep.register_option(RS2_OPTION_DEPTH_UNITS, std::make_shared<const_value_option>("Number of meters represented by a single depth unit",
                 lazy<float>([]() { return 0.001f; })));

src/ds5/ds5-options.cpp

@@ -388,6 +388,7 @@ namespace librealsense
 
         _hwm.send(cmd);
         _record_action(*this);
+        notify(value);
     }
 
     float depth_scale_option::query() const

src/ds5/ds5-options.h

@@ -181,7 +181,7 @@ namespace librealsense
         std::shared_ptr<auto_exposure_mechanism>     _auto_exposure;
     };
 
-    class depth_scale_option : public option
+    class depth_scale_option : public option, public observable_option
     {
     public:
         depth_scale_option(hw_monitor& hwm);
@@ -199,6 +199,7 @@ namespace librealsense
         {
             _record_action = record_action;
         }
+
     private:
         ds::depth_table_control get_depth_table(ds::advanced_query_mode mode) const;
         std::function<void(const option &)> _record_action = [](const option&) {};

src/option.h

@@ -16,6 +16,26 @@
 
 namespace librealsense
 {
+    class observable_option
+    {
+    public:
+        void add_observer(std::function<void(float)> callback)
+        {
+            _callbacks.push_back(callback);
+        }
+
+        void notify(float val)
+        {
+            for (auto callback : _callbacks)
+            {
+                callback(val);
+            }
+        }
+
+    private:
+        std::vector<std::function<void(float)>> _callbacks;
+    };
+
     class readonly_option : public option
     {
     public: