Send event, so that DeviceManager does not depend on DeviceToolBar...

... freeing it and DevicePrefs from cycles

src/DeviceManager.cpp

@@ -38,7 +38,8 @@
 #include "AudioIOBase.h"
 
 #include "DeviceChange.h" // for HAVE_DEVICE_CHANGE
-#include "toolbars/DeviceToolBar.h"
+
+wxDEFINE_EVENT(EVT_RESCANNED_DEVICES, wxCommandEvent);
 
 DeviceManager DeviceManager::dm;
 
@@ -299,13 +300,11 @@ void DeviceManager::Rescan()
    }
 
    // If this was not an initial scan update each device toolbar.
-   // Hosts may have disappeared or appeared so a complete repopulate is needed.
-   if (m_inited) {
-      for ( auto pProject : AllProjects{} ) {
-         auto &dt = DeviceToolBar::Get( *pProject );
-         dt.RefillCombos();
-      }
+   if ( m_inited ) {
+      wxCommandEvent e{ EVT_RESCANNED_DEVICES };
+      wxTheApp->ProcessEvent( e );
    }
+
    m_inited = true;
    mRescanTime = std::chrono::steady_clock::now();
 }

src/DeviceManager.h

@@ -23,12 +23,17 @@
 #include <chrono>
 #include <vector>
 
+#include <wx/event.h> // to declare a custom event type
 #include <wx/string.h> // member variables
 
 #if defined(EXPERIMENTAL_DEVICE_CHANGE_HANDLER)
 #include "DeviceChange.h"
 #endif
 
+// Event sent to the application
+wxDECLARE_EXPORTED_EVENT(AUDACITY_DLL_API,
+                         EVT_RESCANNED_DEVICES, wxCommandEvent);
+
 typedef struct DeviceSourceMap {
    int deviceIndex;
    int sourceIndex;

src/toolbars/DeviceToolBar.cpp

@@ -75,6 +75,8 @@ static int DeviceToolbarPrefsID()
 DeviceToolBar::DeviceToolBar()
 : ToolBar(DeviceBarID, _("Device"), wxT("Device"), true)
 {
+   wxTheApp->Bind( EVT_RESCANNED_DEVICES,
+      &DeviceToolBar::OnRescannedDevices, this );
 }
 
 DeviceToolBar::~DeviceToolBar()
@@ -628,6 +630,13 @@ void DeviceToolBar::FillHostDevices()
    // The setting of the Device is left up to OnChoice
 }
 
+void DeviceToolBar::OnRescannedDevices( wxCommandEvent &event )
+{
+   event.Skip();
+   // Hosts may have disappeared or appeared so a complete repopulate is needed.
+   RefillCombos();
+}
+
 //return 1 if host changed, 0 otherwise.
 int DeviceToolBar::ChangeHost()
 {

src/toolbars/DeviceToolBar.h

@@ -59,6 +59,8 @@ class DeviceToolBar final : public ToolBar {
    void RefillCombos();
 
  private:
+   void OnRescannedDevices( wxCommandEvent& );
+
    int  ChangeHost();
    void ChangeDevice(bool isInput);
    void FillHosts();