Fix waveform concurrency issues. Potentially fixes Bug #1383404.

* Use const shared pointers for waveforms.
* Move all std::vector sizing operations to the Waveform constructor. No
  vector state is allowed to change after the constructor finishes.
* Clarify comments.
* Remove waveform mutex usage in WOverview variants.
* Use the track's waveform pointer to atomically swap the waveform
  rather than mutating the waveform in place.
* Remove unused code.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/waveform/renderers/glwaveformrenderersimplesignal.cpp b/src/waveform/renderers/glwaveformrenderersimplesignal.cpp
index 197a124035..2b39e7842b 100644
--- a/src/waveform/renderers/glwaveformrenderersimplesignal.cpp
+++ b/src/waveform/renderers/glwaveformrenderersimplesignal.cpp
@@ -32,8 +32,8 @@ void GLWaveformRendererSimpleSignal::draw(QPainter* painter, QPaintEvent* /*even
         return;
     }
 
-    const Waveform* waveform = pTrack->getWaveform();
-    if (waveform == NULL) {
+    ConstWaveformPointer waveform = pTrack->getWaveform();
+    if (waveform.isNull()) {
         return;
     }