MMDevice: adds functions to XYStage and Stage to let them signal whether they use callbacks

MMDevice/DeviceBase.h

@@ -1893,6 +1893,14 @@ class CStageBase : public CDeviceBase<MM::Stage, U>
       return DEVICE_OK;
    }
 
+   /**
+   * @brief Return true when your device adapter uses OnStagePositionChanged callbacks.
+   */
+   virtual bool UsesOnStagePositionChanged()
+   {
+      return false;
+   }
+
    virtual int IsStageLinearSequenceable(bool& isSequenceable) const
    {
       isSequenceable = false;
@@ -2103,6 +2111,14 @@ class CXYStageBase : public CDeviceBase<MM::XYStage, U>
       return this->SetPositionSteps(xSteps+x, ySteps+y);
    }
 
+   /**
+   * @brief Return true when your device adapter uses OnXYStagePositionChanged callbacks.
+   */
+   virtual bool UsesOnXYStagePositionChanged()
+   {
+      return false;
+   }
+
    virtual int Move(double /*vx*/, double /*vy*/)
    {
       return DEVICE_UNSUPPORTED_COMMAND;

MMDevice/MMDevice.h

@@ -28,7 +28,7 @@
 // Header version
 // If any of the class definitions changes, the interface version
 // must be incremented
-#define DEVICE_INTERFACE_VERSION 74
+#define DEVICE_INTERFACE_VERSION 75
 ///////////////////////////////////////////////////////////////////////////////
 
 // N.B.
@@ -603,6 +603,15 @@ namespace MM {
       virtual int SetOrigin() = 0;
       virtual int GetLimits(double& lower, double& upper) = 0;
 
+      /**
+      * @brief Stages can use the OnStagePositionChanged callback to signal
+      * updates about their position.  Some adapters do so, others do not,
+      * in which case the UI code should use polling.  This function signals whether
+      * the device adapters uses callbacks, so that the UI knows it does not need
+      * to poll this device
+      */
+      virtual bool UsesOnStagePositionChanged() = 0;
+
       /**
        * @brief Return the focus direction.
        *
@@ -709,6 +718,15 @@ namespace MM {
       virtual int Home() = 0;
       virtual int Stop() = 0;
 
+      /**
+      * @brief XY stages can use the OnXYStagePositionChanged callback to signal
+      * updates about their position.  Some stage adapters do so, others do not,
+      * in which case the UI code can use polling.  This function signals whether
+      * the device adapters uses callbacks, so that the UI knows it does not need
+      * to poll this device
+      */
+      virtual bool UsesOnXYStagePositionChanged() = 0;
+
       /**
        * @brief Define the current position as the (hardware) origin (0, 0).
        */