einginelibrary: In el_track_impl::set_overview_waveform_data, add explanatory comment

Co-authored-by: Adam Szmigin <smidge@xsco.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/djinterop/enginelibrary/el_track_impl.cpp b/src/djinterop/enginelibrary/el_track_impl.cpp
index 61fc142..3ab3d7e 100644
--- a/src/djinterop/enginelibrary/el_track_impl.cpp
+++ b/src/djinterop/enginelibrary/el_track_impl.cpp
@@ -201,6 +201,9 @@ overview_waveform_data el_track_impl::get_overview_waveform_data()
 
 void el_track_impl::set_overview_waveform_data(overview_waveform_data data)
 {
+    // As the overview waveform does not store opacity, it is defaulted to 255
+    // when read back.  If we also set it to 255 here, we can apply a check in
+    // `set_perfdata` that a round-trip encode/decode gives the same data.
     for (auto&& entry : data.waveform)
     {
         entry.low.opacity = 255;