Move MeterPanelBase to new files...

... which frees AudioIOBase, QualityPrefs, and ProjectAudioIO from cycles

src/widgets/Meter.cpp

@@ -2151,10 +2151,6 @@ MeterAx::~MeterAx()
 {
 }
 
-MeterPanelBase::~MeterPanelBase()
-{
-}
-
 // Performs the default action. childId is 0 (the action for this object)
 // or > 0 (the action for a child).
 // Return wxACC_NOT_SUPPORTED if there is no default action for this

src/widgets/Meter.h

@@ -23,6 +23,7 @@
 
 #include "../SampleFormat.h"
 #include "../Prefs.h"
+#include "MeterPanelBase.h" // to inherit
 #include "Ruler.h" // member variable
 
 class AudacityProject;
@@ -87,22 +88,6 @@ class MeterUpdateQueue
 
 class MeterAx;
 
-class MeterPanelBase /* not final */
-   : public wxPanelWrapper
-{
-public:
-   using wxPanelWrapper::wxPanelWrapper;
-   ~MeterPanelBase() override;
-
-   virtual void Clear() = 0;
-   virtual void Reset(double sampleRate, bool resetClipping) = 0;
-   virtual void UpdateDisplay(unsigned numChannels,
-                      int numFrames, float *sampleData) = 0;
-   virtual bool IsMeterDisabled() const = 0;
-   virtual float GetMaxPeak() const = 0;
-private:
-};
-
 /********************************************************************//**
 \brief MeterPanel is a panel that paints the meter used for monitoring
 or playback.

src/widgets/MeterPanelBase.cpp

@@ -0,0 +1,15 @@
+/**********************************************************************
+
+Audacity: A Digital Audio Editor
+
+MeterPanelBase.cpp
+
+Paul Licameli split from Meter.cpp
+
+**********************************************************************/
+
+#include "MeterPanelBase.h"
+
+MeterPanelBase::~MeterPanelBase()
+{
+}

src/widgets/MeterPanelBase.h

@@ -0,0 +1,32 @@
+/**********************************************************************
+
+Audacity: A Digital Audio Editor
+
+MeterPanelBase.h
+
+Paul Licameli split from Meter.h
+
+**********************************************************************/
+
+#ifndef __AUDACITY_METER_PANEL_BASE__
+#define __AUDACITY_METER_PANEL_BASE__
+
+#include "wxPanelWrapper.h"
+
+class MeterPanelBase /* not final */
+   : public wxPanelWrapper
+{
+public:
+   using wxPanelWrapper::wxPanelWrapper;
+   ~MeterPanelBase() override;
+
+   virtual void Clear() = 0;
+   virtual void Reset(double sampleRate, bool resetClipping) = 0;
+   virtual void UpdateDisplay(unsigned numChannels,
+                      int numFrames, float *sampleData) = 0;
+   virtual bool IsMeterDisabled() const = 0;
+   virtual float GetMaxPeak() const = 0;
+private:
+};
+
+#endif