Do not require AudacityApp.h when using global file history

src/widgets/FileHistory.cpp

@@ -9,7 +9,7 @@
 *******************************************************************//**
 
 \class FileHistory
-\brief Similar to FileHistory, but customized to our needs.
+\brief Similar to wxFileHistory, but customized to our needs.
 
 *//*******************************************************************/
 
@@ -21,6 +21,9 @@
 #include <wx/menu.h>
 
 #include "../Internat.h"
+#include "../Prefs.h"
+
+#include <mutex>
 
 FileHistory::FileHistory(size_t maxfiles, wxWindowID base)
 {
@@ -32,6 +35,19 @@ FileHistory::~FileHistory()
 {
 }
 
+FileHistory &FileHistory::Global()
+{
+   // TODO - read the number of files to store in history from preferences
+   static FileHistory history{
+      ID_RECENT_LAST - ID_RECENT_FIRST + 1, ID_RECENT_CLEAR };
+   static std::once_flag flag;
+   std::call_once( flag, [&]{
+      history.Load(*gPrefs, wxT("RecentFiles"));
+   });
+
+   return history;
+}
+
 // File history management
 void FileHistory::AddFileToHistory(const FilePath & file, bool update)
 {

src/widgets/FileHistory.h

@@ -28,6 +28,15 @@ class AUDACITY_DLL_API FileHistory
    FileHistory(size_t maxfiles = 12, wxWindowID idbase = wxID_FILE);
    virtual ~FileHistory();
 
+   // These constants define the range of IDs reserved by the global file history
+   enum {
+      ID_RECENT_CLEAR = 6100,
+      ID_RECENT_FIRST = 6101,
+      ID_RECENT_LAST  = 6112
+   };
+
+   static FileHistory &Global();
+
    void AddFileToHistory(const FilePath & file, bool update = true);
    void RemoveFileFromHistory(size_t i, bool update = true);
    void Clear();