Don't make assumptions about types of timer interval constants ...

... where they must mix with un-typed numbers, including calls to wxTimer
methods.  Change the name of one so it doesn't mention the period.

Do not use duration_cast, but use other conversions that check for non-lossiness
at compile time.

src/ScrubState.cpp

@@ -358,7 +358,7 @@ bool ScrubbingPlaybackPolicy::Done(
 std::chrono::milliseconds
 ScrubbingPlaybackPolicy::SleepInterval( PlaybackSchedule & )
 {
-   return ScrubPollInterval_ms;
+   return ScrubPollInterval;
 }
 
 PlaybackSlice ScrubbingPlaybackPolicy::GetPlaybackSlice(

src/ScrubState.h

@@ -106,6 +106,6 @@ struct ScrubState
    static double GetLastScrubTime();
 };
 
-static constexpr auto ScrubPollInterval_ms = std::chrono::milliseconds{50};
+static constexpr auto ScrubPollInterval = std::chrono::milliseconds{50};
 
 #endif

src/TrackPanel.cpp

@@ -381,7 +381,7 @@ void TrackPanel::OnIdle(wxIdleEvent& event)
    // The window must be ready when the timer fires (#1401)
    if (IsShownOnScreen())
    {
-      mTimer.Start(kTimerInterval.count(), FALSE);
+      mTimer.Start(std::chrono::milliseconds{kTimerInterval}.count(), FALSE);
 
       // Timer is started, we don't need the event anymore
       GetProjectFrame( *GetProject() ).Unbind(wxEVT_IDLE,
@@ -727,7 +727,7 @@ void TrackPanel::OnMouseEvent(wxMouseEvent & event)
       // When this timer fires, we call TrackPanel::OnTimer and
       // possibly update the screen for offscreen scrolling.
       mTimer.Stop();
-      mTimer.Start(kTimerInterval.count(), FALSE);
+      mTimer.Start(std::chrono::milliseconds{kTimerInterval}.count(), FALSE);
    }
 
 

src/tracks/ui/PlayIndicatorOverlay.cpp

@@ -190,7 +190,9 @@ void PlayIndicatorOverlay::OnTimer(wxCommandEvent &event)
 
       // Use a small tolerance to avoid flicker of play head pinned all the way
       // left or right
-      const auto tolerance = pinned ? 1.5 * kTimerInterval.count() / 1000.0 : 0;
+      const auto tolerance = pinned
+         ? 1.5 * std::chrono::duration<double>{kTimerInterval}.count()
+         : 0;
       bool onScreen = playPos >= 0.0 &&
          between_incexc(viewInfo.h - tolerance,
          playPos,

src/tracks/ui/Scrubbing.cpp

@@ -52,7 +52,8 @@ enum {
    ScrubSpeedStepsPerOctave = 4,
 #endif
 
-   kOneSecondCountdown = 1000 / ScrubPollInterval_ms.count(),
+   kOneSecondCountdown =
+      1000 / std::chrono::milliseconds{ScrubPollInterval}.count(),
 };
 
 static constexpr PlaybackPolicy::Duration MinStutter{0.2};
@@ -153,7 +154,7 @@ auto Scrubber::ScrubPollerThread::Entry() -> ExitCode
 {
    while( !TestDestroy() )
    {
-      std::this_thread::sleep_for(ScrubPollInterval_ms);
+      std::this_thread::sleep_for(ScrubPollInterval);
       mScrubber.ContinueScrubbingPoll();
    }
    return 0;
@@ -417,12 +418,12 @@ bool Scrubber::MaybeStartScrubbing(wxCoord xx)
             // execute too much else
             options.playbackStreamPrimer = [this](){
                ContinueScrubbingPoll();
-               return ScrubPollInterval_ms;
+               return ScrubPollInterval;
             };
 #endif
             options.playNonWaveTracks = false;
             options.envelope = nullptr;
-            mOptions.delay = ScrubPollInterval_ms;
+            mOptions.delay = ScrubPollInterval;
             mOptions.isKeyboardScrubbing = false;
             mOptions.initSpeed = 0;
             mOptions.minSpeed = 0.0;
@@ -518,7 +519,7 @@ bool Scrubber::StartKeyboardScrubbing(double time0, bool backwards)
    // execute too much else
    options.playbackStreamPrimer = [this]() {
       ContinueScrubbingPoll();
-      return ScrubPollInterval_ms;
+      return ScrubPollInterval;
    };
 #endif
 
@@ -527,7 +528,7 @@ bool Scrubber::StartKeyboardScrubbing(double time0, bool backwards)
 
    // delay and minStutterTime are used in AudioIO::AllocateBuffers() for setting the
    // values of mPlaybackQueueMinimum and mPlaybackSamplesToCopy respectively.
-   mOptions.delay = ScrubPollInterval_ms;
+   mOptions.delay = ScrubPollInterval;
    mOptions.minStutterTime = mOptions.delay;
 
    mOptions.initSpeed = GetKeyboardScrubbingSpeed();
@@ -728,8 +729,9 @@ void Scrubber::StartPolling()
    mpThread->Create(4096);
    mpThread->Run();
 #endif
-
-   mPoller->Start(ScrubPollInterval_ms.count() * 0.9);
+
+   mPoller->Start( 0.9 *
+      std::chrono::duration<double, std::milli>{ScrubPollInterval}.count());
 }
 
 void Scrubber::StopPolling()