From 72f66b70969bd71ab71a39571e9ad2ee4cb8c238 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Sat, 4 Jan 2020 12:11:32 -0500
Subject: [PATCH] Mac: don't crash in Preferences when there is no project
 window...

... and you press Preview in Spectrogram preferences.

And complete null checks on GetActiveProject calls in src/prefs.

And in fact, don't even show the useless Preview button when there is no
project.
---
 src/prefs/SpectrumPrefs.cpp | 20 +++++++++++++-------
 src/prefs/WaveformPrefs.cpp |  9 ++++++---
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/src/prefs/SpectrumPrefs.cpp b/src/prefs/SpectrumPrefs.cpp
index fb937b783..dcb62514a 100644
--- a/src/prefs/SpectrumPrefs.cpp
+++ b/src/prefs/SpectrumPrefs.cpp
@@ -429,9 +429,12 @@ void SpectrumPrefs::Rollback()
    }
 
    if (isOpenPage) {
-      auto &tp = TrackPanel::Get ( *::GetActiveProject() );
-      tp.UpdateVRulers();
-      tp.Refresh(false);
+      auto pProject = ::GetActiveProject();
+      if ( pProject ) {
+         auto &tp = TrackPanel::Get ( *pProject );
+         tp.UpdateVRulers();
+         tp.Refresh(false);
+      }
    }
 }
 
@@ -477,9 +480,12 @@ void SpectrumPrefs::Preview()
    }
 
    if (isOpenPage) {
-      auto &tp = TrackPanel::Get( *::GetActiveProject() );
-      tp.UpdateVRulers();
-      tp.Refresh(false);
+      auto pProject = ::GetActiveProject();
+      if ( pProject ) {
+         auto &tp = TrackPanel::Get( *pProject );
+         tp.UpdateVRulers();
+         tp.Refresh(false);
+      }
    }
 }
 
@@ -500,7 +506,7 @@ bool SpectrumPrefs::Commit()
 
 bool SpectrumPrefs::ShowsPreviewButton()
 {
-   return true;
+   return GetActiveProject() != nullptr;
 }
 
 void SpectrumPrefs::OnControl(wxCommandEvent&)
diff --git a/src/prefs/WaveformPrefs.cpp b/src/prefs/WaveformPrefs.cpp
index e1a081fa0..d947cc607 100644
--- a/src/prefs/WaveformPrefs.cpp
+++ b/src/prefs/WaveformPrefs.cpp
@@ -191,9 +191,12 @@ bool WaveformPrefs::Commit()
    }
 
    if (isOpenPage) {
-      auto &tp = TrackPanel::Get( *::GetActiveProject() );
-      tp.UpdateVRulers();
-      tp.Refresh(false);
+      auto pProject = ::GetActiveProject();
+      if ( pProject ) {
+         auto &tp = TrackPanel::Get( *pProject );
+         tp.UpdateVRulers();
+         tp.Refresh(false);
+      }
    }
 
    return true;