From d92a68f076b1fb2f6b0c3c4b30a6fe711e56c4b4 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Thu, 17 Dec 2020 11:58:31 -0500
Subject: [PATCH] ViewInfo does not depend on AudioIOBase...

... ViewInfo should only be concerned with screen geometry.

(And so it won't depend on AudioIO (even higher level) after stream time moves
there.)

PlaybackScroller receives the timer event directly (not from ViewInfo) and
caches playback position instead.  Then, as before, it propagates the event
to PlayIndicatorOverlay.
---
 src/ProjectWindow.cpp                  |  9 ++++++---
 src/ProjectWindow.h                    |  6 ++++++
 src/ViewInfo.cpp                       | 18 +-----------------
 src/ViewInfo.h                         |  7 -------
 src/tracks/ui/PlayIndicatorOverlay.cpp | 10 +++++-----
 5 files changed, 18 insertions(+), 32 deletions(-)

diff --git a/src/ProjectWindow.cpp b/src/ProjectWindow.cpp
index 179529dd6..8484efb8b 100644
--- a/src/ProjectWindow.cpp
+++ b/src/ProjectWindow.cpp
@@ -1660,7 +1660,7 @@ void ProjectWindow::TP_HandleResize()
 ProjectWindow::PlaybackScroller::PlaybackScroller(AudacityProject *project)
 : mProject(project)
 {
-   ViewInfo::Get( *mProject ).Bind(EVT_TRACK_PANEL_TIMER,
+   mProject->Bind(EVT_TRACK_PANEL_TIMER,
       &PlaybackScroller::OnTimer,
       this);
 }
@@ -1670,9 +1670,12 @@ void ProjectWindow::PlaybackScroller::OnTimer(wxCommandEvent &event)
    // Let other listeners get the notification
    event.Skip();
 
+   auto gAudioIO = AudioIOBase::Get();
+   mRecentStreamTime = gAudioIO->GetStreamTime();
+
    auto cleanup = finally([&]{
       // Propagate the message to other listeners bound to this
-      this->ProcessEvent( event );
+      this->SafelyProcessEvent( event );
    });
 
    if(!ProjectAudioIO::Get( *mProject ).IsAudioActive())
@@ -1692,7 +1695,7 @@ void ProjectWindow::PlaybackScroller::OnTimer(wxCommandEvent &event)
 
       auto &viewInfo = ViewInfo::Get( *mProject );
       auto &trackPanel = GetProjectPanel( *mProject );
-      const int posX = viewInfo.TimeToPosition(viewInfo.mRecentStreamTime);
+      const int posX = viewInfo.TimeToPosition(mRecentStreamTime);
       auto width = viewInfo.GetTracksUsableWidth();
       int deltaX;
       switch (mMode)
diff --git a/src/ProjectWindow.h b/src/ProjectWindow.h
index c124c06ff..54b324497 100644
--- a/src/ProjectWindow.h
+++ b/src/ProjectWindow.h
@@ -75,11 +75,17 @@ public:
          mMode = mode;
       }
 
+      double GetRecentStreamTime() const { return mRecentStreamTime; }
+
    private:
       void OnTimer(wxCommandEvent &event);
 
       AudacityProject *mProject;
       Mode mMode { Mode::Off };
+
+      // During timer update, grab the volatile stream time just once, so that
+      // various other drawing code can use the exact same value.
+      double mRecentStreamTime{ -1.0 };
    };
    PlaybackScroller &GetPlaybackScroller() { return *mPlaybackScroller; }
 
diff --git a/src/ViewInfo.cpp b/src/ViewInfo.cpp
index 6ba76e61b..4c39a7157 100644
--- a/src/ViewInfo.cpp
+++ b/src/ViewInfo.cpp
@@ -14,7 +14,6 @@ Paul Licameli
 
 #include <algorithm>
 
-#include "AudioIOBase.h"
 #include "Prefs.h"
 #include "Project.h"
 #include "xml/XMLWriter.h"
@@ -150,12 +149,7 @@ void NotifyingSelectedRegion::Notify( bool delayed )
 
 static const AudacityProject::AttachedObjects::RegisteredFactory key{
    []( AudacityProject &project ) {
-      auto result =
-         std::make_unique<ViewInfo>(0.0, 1.0, ZoomInfo::GetDefaultZoom());
-      project.Bind(EVT_TRACK_PANEL_TIMER,
-         &ViewInfo::OnTimer,
-         result.get());
-      return std::move( result );
+      return std::make_unique<ViewInfo>(0.0, 1.0, ZoomInfo::GetDefaultZoom());
    }
 };
 
@@ -180,7 +174,6 @@ ViewInfo::ViewInfo(double start, double screenDuration, double pixelsPerSecond)
    , scrollStep(16)
    , bUpdateTrackIndicator(true)
    , bScrollBeyondZero(false)
-   , mRecentStreamTime(-1.0)
 {
    UpdatePrefs();
 }
@@ -248,15 +241,6 @@ bool ViewInfo::ReadXMLAttribute(const wxChar *attr, const wxChar *value)
    return false;
 }
 
-void ViewInfo::OnTimer(wxCommandEvent &event)
-{
-   auto gAudioIO = AudioIOBase::Get();
-   mRecentStreamTime = gAudioIO->GetStreamTime();
-   event.Skip();
-   // Propagate the message to other listeners bound to this
-   this->ProcessEvent( event );
-}
-
 int ViewInfo::UpdateScrollPrefsID()
 {
    static int value = wxNewId();
diff --git a/src/ViewInfo.h b/src/ViewInfo.h
index 4b4182c0b..46a09769a 100644
--- a/src/ViewInfo.h
+++ b/src/ViewInfo.h
@@ -224,16 +224,9 @@ public:
    bool bScrollBeyondZero;
    bool bAdjustSelectionEdges;
 
-   // During timer update, grab the volatile stream time just once, so that
-   // various other drawing code can use the exact same value.
-   double mRecentStreamTime;
-
    void WriteXMLAttributes(XMLWriter &xmlFile) const;
    bool ReadXMLAttribute(const wxChar *attr, const wxChar *value);
 
-   // Receive track panel timer notifications
-   void OnTimer(wxCommandEvent &event);
-
 private:
    int mHeight{ 0 };
 };
diff --git a/src/tracks/ui/PlayIndicatorOverlay.cpp b/src/tracks/ui/PlayIndicatorOverlay.cpp
index f808c54ce..6d1fe64f7 100644
--- a/src/tracks/ui/PlayIndicatorOverlay.cpp
+++ b/src/tracks/ui/PlayIndicatorOverlay.cpp
@@ -174,13 +174,13 @@ void PlayIndicatorOverlay::OnTimer(wxCommandEvent &event)
       }
    }
    else {
-      // Calculate the horizontal position of the indicator
-      const double playPos = viewInfo.mRecentStreamTime;
-
       auto &window = ProjectWindow::Get( *mProject );
+      auto &scroller = window.GetPlaybackScroller();
+      // Calculate the horizontal position of the indicator
+      const double playPos = scroller.GetRecentStreamTime();
+
       using Mode = ProjectWindow::PlaybackScroller::Mode;
-      const Mode mode =
-         window.GetPlaybackScroller().GetMode();
+      const Mode mode = scroller.GetMode();
       const bool pinned = ( mode == Mode::Pinned || mode == Mode::Right );
 
       // Use a small tolerance to avoid flicker of play head pinned all the way