Decouple class AudacityProject from some attached frames...

... use registered factories instead, so class AudacityProject needn't know
the other classes.

This frees 9 .cpp files, related to various non-modal dialogs, to higher
levels out of the big strongly connected component, as determined by
scripts/graph.pl!

But in reality there is still link dependency on them that the script does not
detect.  The remaining dependency is via the declarations of ViewMenu,
EffectMenu, etc. in Menus.cpp.

That could be broken with a registration system for menus.

src/AudacityApp.cpp

@@ -75,7 +75,6 @@ It handles initialization and termination by subclassing wxApp.
 #include "DirManager.h"
 #include "commands/CommandHandler.h"
 #include "commands/AppCommandEvent.h"
-#include "effects/Contrast.h"
 #include "widgets/ASlider.h"
 #include "FFmpeg.h"
 #include "LangChoice.h"

src/AudacityHeaders.h

@@ -51,7 +51,6 @@
 #include "Envelope.h"
 #include "FFT.h"
 #include "FileFormats.h"
-#include "FreqWindow.h"
 #include "ImageManipulation.h"
 #include "LabelTrack.h"
 #include "Mix.h"

src/Project.cpp

@@ -98,22 +98,17 @@ scroll information.  It also has some status flags.
 #include "AdornedRulerPanel.h"
 #include "Clipboard.h"
 #include "widgets/FileHistory.h"
-#include "FreqWindow.h"
-#include "effects/Contrast.h"
 #include "AutoRecovery.h"
 #include "AColor.h"
 #include "AudioIO.h"
-#include "BatchProcessDialog.h"
 #include "Dependencies.h"
 #include "Diags.h"
-#include "HistoryWindow.h"
+#include "export/Export.h"
 #include "InconsistencyException.h"
-#include "MixerBoard.h"
 #include "import/Import.h"
 #include "KeyboardCapture.h"
 #include "LabelTrack.h"
 #include "Legacy.h"
-#include "LyricsWindow.h"
 #include "Menus.h"
 #include "MissingAliasFileDialog.h"
 #include "Mix.h"
@@ -1352,6 +1347,8 @@ AudacityProject::AudacityProject(wxWindow * parent, wxWindowID id,
 #endif
 
    AttachedObjects::BuildAll();
+   // But not for the attached windows.  They get built only on demand, such as
+   // from menu items.
 }
 
 AudacityProject::~AudacityProject()
@@ -2479,14 +2476,6 @@ void AudacityProject::OnCloseWindow(wxCloseEvent & event)
       return;
    }
 
-   // TODO: consider postponing these steps until after the possible veto
-   // below:  closing the two analysis dialogs, and stopping audio streams.
-   // Streams can be for play, recording, or monitoring.  But maybe it still
-   // makes sense to stop any recording before putting up the dialog.
-
-   mFreqWindow.reset();
-   mContrastDialog.reset();
-
    // Check to see if we were playing or recording
    // audio, and if so, make sure Audio I/O is completely finished.
    // The main point of this is to properly push the state
@@ -2590,16 +2579,6 @@ void AudacityProject::OnCloseWindow(wxCloseEvent & event)
 
    projectFileIO.CloseLock();
 
-   // Get rid of the history window
-   // LL:  Destroy it before the TrackPanel and ToolBars since they
-   //      may/will get additional wxEVT_PAINT events since window
-   //      destruction may be queued.  This seems to only be a problem
-   //      on the Mac.
-   if (mHistoryWindow) {
-      mHistoryWindow->Destroy();
-      mHistoryWindow = NULL;
-   }
-
    // Some of the AdornedRulerPanel functions refer to the TrackPanel, so destroy this
    // before the TrackPanel is destroyed. This change was needed to stop Audacity
    // crashing when running with Jaws on Windows 10 1703.
@@ -5507,64 +5486,6 @@ void AudacityProject::PlaybackScroller::OnTimer(wxCommandEvent &event)
    }
 }
 
-LyricsWindow* AudacityProject::GetLyricsWindow(bool create)
-{
-   if (create && !mLyricsWindow)
-      mLyricsWindow = safenew LyricsWindow{ this };
-   return mLyricsWindow;
-}
-
-MixerBoardFrame* AudacityProject::GetMixerBoardFrame(bool create)
-{
-   if (create && !mMixerBoardFrame)
-      mMixerBoardFrame = safenew MixerBoardFrame{ this };
-   return mMixerBoardFrame;
-}
-
-HistoryWindow *AudacityProject::GetHistoryWindow(bool create)
-{
-   auto &project = *this;
-   auto &undoManager = UndoManager::Get( project );
-   if (create && !mHistoryWindow)
-      mHistoryWindow = safenew HistoryWindow{ this, &undoManager };
-   return mHistoryWindow;
-}
-
-MacrosWindow *AudacityProject::GetMacrosWindow(bool bExpanded, bool create)
-{
-   if (create && !mMacrosWindow)
-      mMacrosWindow = safenew MacrosWindow{ this, bExpanded };
-
-   if (mMacrosWindow) {
-      mMacrosWindow->Show();
-      mMacrosWindow->Raise();
-      mMacrosWindow->UpdateDisplay( bExpanded );
-   }
-   return mMacrosWindow;
-}
-
-FreqWindow *AudacityProject::GetFreqWindow(bool create)
-{
-   if (create && !mFreqWindow)
-      mFreqWindow.reset( safenew FreqWindow{
-         this, -1, _("Frequency Analysis"),
-         wxPoint{ 150, 150 }
-      } );
-   return mFreqWindow.get();
-}
-
-ContrastDialog *AudacityProject::GetContrastDialog(bool create)
-{
-   // All of this goes away when the Contrast Dialog is converted to a module
-   if(create && !mContrastDialog)
-      mContrastDialog.reset( safenew ContrastDialog{
-         this, -1, _("Contrast Analysis (WCAG 2 compliance)"),
-         wxPoint{ 150, 150 }
-      } );
-
-   return mContrastDialog.get();
-}
-
 void AudacityProject::ZoomInByFactor( double ZoomFactor )
 {
    auto &project = *this;

src/Project.h

@@ -61,7 +61,6 @@ class TrackList;
 
 class TrackPanel;
 class FreqWindow;
-class ContrastDialog;
 class MeterPanel;
 
 // toolbar classes
@@ -76,11 +75,7 @@ class TranscriptionToolBar;
 
 // windows and frames
 class AdornedRulerPanel;
-class HistoryWindow;
-class MacrosWindow;
 class LyricsWindow;
-class MixerBoard;
-class MixerBoardFrame;
 
 struct AudioIOStartStreamOptions;
 struct UndoState;
@@ -166,9 +161,17 @@ class WaveTrack;
 
 class MenuManager;
 
+// Container of various objects associated with the project, which is
+// responsible for destroying them
 using AttachedObjects = ClientData::Site<
    AudacityProject, ClientData::Base, ClientData::SkipCopying, std::shared_ptr
 >;
+// Container of pointers to various windows associated with the project, which
+// is not responsible for destroying them -- wxWidgets handles that instead
+using AttachedWindows = ClientData::Site<
+   AudacityProject, wxWindow, ClientData::SkipCopying, wxWeakRef
+>;
+
 class AUDACITY_DLL_API AudacityProject final : public wxFrame,
                                      public TrackPanelListener,
                                      public SelectionBarListener,
@@ -177,9 +180,11 @@ class AUDACITY_DLL_API AudacityProject final : public wxFrame,
                                      public AudioIOListener,
                                      private PrefsListener
    , public AttachedObjects
+   , public AttachedWindows
 {
  public:
    using AttachedObjects = ::AttachedObjects;
+   using AttachedWindows = ::AttachedWindows;
 
    AudacityProject(wxWindow * parent, wxWindowID id,
                    const wxPoint & pos, const wxSize & size);
@@ -435,13 +440,6 @@ public:
    MeterPanel *GetCaptureMeter();
    void SetCaptureMeter(MeterPanel *capture);
 
-   LyricsWindow* GetLyricsWindow(bool create = false);
-   MixerBoardFrame* GetMixerBoardFrame(bool create = false);
-   HistoryWindow *GetHistoryWindow(bool create = false);
-   MacrosWindow *GetMacrosWindow(bool bExpanded, bool create = false);
-   FreqWindow *GetFreqWindow(bool create = false);
-   ContrastDialog *GetContrastDialog(bool create = false);
-
 private:
    bool SnapSelection();
 
@@ -562,14 +560,6 @@ private:
    bool mActive{ true };
    bool mIconized;
 
-   MacrosWindow *mMacrosWindow{};
-   HistoryWindow *mHistoryWindow{};
-   LyricsWindow* mLyricsWindow{};
-   MixerBoardFrame* mMixerBoardFrame{};
-
-   Destroy_ptr<FreqWindow> mFreqWindow;
-   Destroy_ptr<ContrastDialog> mContrastDialog;
-
    bool mShownOnce{ false };
 
    // Project owned meters

src/menus/PluginMenus.cpp

@@ -23,6 +23,32 @@
 // private helper classes and functions
 namespace {
 
+AudacityProject::AttachedWindows::RegisteredFactory sContrastDialogKey{
+   []( AudacityProject &parent ) -> wxWeakRef< wxWindow > {
+      return safenew ContrastDialog(
+         &parent, -1, _("Contrast Analysis (WCAG 2 compliance)"),
+         wxPoint{ 150, 150 }
+      );
+   }
+};
+
+AudacityProject::AttachedWindows::RegisteredFactory sFrequencyWindowKey{
+   []( AudacityProject &parent ) -> wxWeakRef< wxWindow > {
+      return safenew FreqWindow(
+         &parent, -1, _("Frequency Analysis"),
+         wxPoint{ 150, 150 }
+      );
+   }
+};
+
+AudacityProject::AttachedWindows::RegisteredFactory sMacrosWindowKey{
+   []( AudacityProject &parent ) -> wxWeakRef< wxWindow > {
+      return safenew MacrosWindow(
+         &parent, true
+      );
+   }
+};
+
 void DoManagePluginsMenu
 (AudacityProject &project, EffectType type)
 {
@@ -591,8 +617,8 @@ void OnManageAnalyzers(const CommandContext &context)
 void OnContrast(const CommandContext &context)
 {
    auto &project = context.project;
-   auto contrastDialog = project.GetContrastDialog(true);
+   auto contrastDialog =
-
+      &project.AttachedWindows::Get< ContrastDialog >( sContrastDialogKey );
 
    contrastDialog->CentreOnParent();
    if( ScreenshotCommand::MayCapture( contrastDialog ) )
@@ -603,8 +629,8 @@ void OnContrast(const CommandContext &context)
 void OnPlotSpectrum(const CommandContext &context)
 {
    auto &project = context.project;
-   auto freqWindow = project.GetFreqWindow(true);
+   auto freqWindow =
-
+      &project.AttachedWindows::Get< FreqWindow >( sFrequencyWindowKey );
 
    if( ScreenshotCommand::MayCapture( freqWindow ) )
       return;
@@ -622,13 +648,25 @@ void OnManageTools(const CommandContext &context )
 void OnManageMacros(const CommandContext &context )
 {
    auto &project = context.project;
-   project.GetMacrosWindow( true, true );
+   auto macrosWindow =
+      &project.AttachedWindows::Get< MacrosWindow >( sMacrosWindowKey );
+   if (macrosWindow) {
+      macrosWindow->Show();
+      macrosWindow->Raise();
+      macrosWindow->UpdateDisplay( true );
+   }
 }
 
 void OnApplyMacrosPalette(const CommandContext &context )
 {
    auto &project = context.project;
-   project.GetMacrosWindow( false, true );
+   auto macrosWindow =
+      &project.AttachedWindows::Get< MacrosWindow >( sMacrosWindowKey );
+   if (macrosWindow) {
+      macrosWindow->Show();
+      macrosWindow->Raise();
+      macrosWindow->UpdateDisplay( false );
+   }
 }
 
 void OnScreenshot(const CommandContext &WXUNUSED(context) )

src/menus/ViewMenus.cpp

@@ -8,6 +8,7 @@
 #include "../Prefs.h"
 #include "../Project.h"
 #include "../TrackPanel.h"
+#include "../UndoManager.h"
 #include "../ViewInfo.h"
 #include "../commands/CommandContext.h"
 #include "../commands/CommandManager.h"
@@ -23,6 +24,25 @@
 // private helper classes and functions
 namespace {
 
+AudacityProject::AttachedWindows::RegisteredFactory sMixerBoardKey{
+   []( AudacityProject &parent ) -> wxWeakRef< wxWindow > {
+      return safenew MixerBoardFrame( &parent );
+   }
+};
+
+AudacityProject::AttachedWindows::RegisteredFactory sHistoryWindowKey{
+   []( AudacityProject &parent ) -> wxWeakRef< wxWindow > {
+      auto &undoManager = UndoManager::Get( parent );
+      return safenew HistoryWindow( &parent, &undoManager );
+   }
+};
+
+AudacityProject::AttachedWindows::RegisteredFactory sLyricsWindowKey{
+   []( AudacityProject &parent ) -> wxWeakRef< wxWindow > {
+      return safenew LyricsWindow( &parent );
+   }
+};
+
 double GetZoomOfSelection( const AudacityProject &project )
 {
    auto &viewInfo = ViewInfo::Get( project );
@@ -323,7 +343,7 @@ void OnHistory(const CommandContext &context)
 {
    auto &project = context.project;
 
-   auto historyWindow = project.GetHistoryWindow(true);
+   auto historyWindow = &project.AttachedWindows::Get( sHistoryWindowKey );
    historyWindow->Show();
    historyWindow->Raise();
 }
@@ -332,7 +352,7 @@ void OnKaraoke(const CommandContext &context)
 {
    auto &project = context.project;
 
-   auto lyricsWindow = project.GetLyricsWindow(true);
+   auto lyricsWindow = &project.AttachedWindows::Get( sLyricsWindowKey );
    lyricsWindow->Show();
    lyricsWindow->Raise();
 }
@@ -341,7 +361,7 @@ void OnMixerBoard(const CommandContext &context)
 {
    auto &project = context.project;
 
-   auto mixerBoardFrame = project.GetMixerBoardFrame(true);
+   auto mixerBoardFrame = &project.AttachedWindows::Get( sMixerBoardKey );
    mixerBoardFrame->Show();
    mixerBoardFrame->Raise();
    mixerBoardFrame->SetFocus();