Highlight MIDI channel buttons

src/NoteTrack.cpp

@@ -251,7 +251,7 @@ void NoteTrack::WarpAndTransposeNotes(double t0, double t1,
 // Draws the midi channel toggle buttons within the given rect.
 // The rect should be evenly divisible by 4 on both axis.
 void NoteTrack::DrawLabelControls
-( const NoteTrack *pTrack, wxDC & dc, const wxRect &rect )
+( const NoteTrack *pTrack, wxDC & dc, const wxRect &rect, int highlightedChannel )
 {
    wxASSERT_MSG(rect.width % 4 == 0, "Midi channel control rect width must be divisible by 4");
    wxASSERT_MSG(rect.height % 4 == 0, "Midi channel control rect height must be divisible by 4");
@@ -273,7 +273,11 @@ void NoteTrack::DrawLabelControls
 
          bool visible = pTrack ? pTrack->IsVisibleChan(chanName - 1) : true;
          if (visible) {
-            AColor::MIDIChannel(&dc, chanName);
+            // highlightedChannel counts 0 based
+            if ( chanName == highlightedChannel + 1 )
+               AColor::LightMIDIChannel(&dc, chanName);
+            else
+               AColor::MIDIChannel(&dc, chanName);
             dc.DrawRectangle(box);
 // two choices: channel is enabled (to see and play) when button is in
 // "up" position (original Audacity style) or in "down" position
@@ -299,7 +303,10 @@ void NoteTrack::DrawLabelControls
                          box.x, box.y + box.height - 1,
                          box.x + box.width - 1, box.y + box.height - 1);
          } else {
-            AColor::MIDIChannel(&dc, 0);
+            if ( chanName == highlightedChannel + 1 )
+               AColor::LightMIDIChannel(&dc, chanName);
+            else
+               AColor::MIDIChannel(&dc, 0);
             dc.DrawRectangle(box);
 #if CHANNEL_ON_IS_DOWN
             AColor::LightMIDIChannel(&dc, 0);

src/NoteTrack.h

@@ -90,7 +90,8 @@ class AUDACITY_DLL_API NoteTrack final
                               const TimeWarper &warper, double semitones);
 
    static void DrawLabelControls
-      ( const NoteTrack *pTrack, wxDC & dc, const wxRect &rect );
+      ( const NoteTrack *pTrack, wxDC & dc, const wxRect &rect,
+        int highlightedChannel = -1 );
    int FindChannel(const wxRect &rect, int mx, int my);
    bool LabelClick(const wxRect &rect, int x, int y, bool right);
 

src/TrackPanel.cpp

@@ -2056,16 +2056,19 @@ void TrackInfo::MinimizeSyncLockDrawFunction
    }
 }
 
+#include "tracks/playabletrack/notetrack/ui/NoteTrackButtonHandle.h"
 void TrackInfo::MidiControlsDrawFunction
 ( TrackPanelDrawingContext &context,
   const wxRect &rect, const Track *pTrack )
 {
 #ifdef EXPERIMENTAL_MIDI_OUT
+   auto target = dynamic_cast<NoteTrackButtonHandle*>( context.target.get() );
+   auto channel = target ? target->GetChannel() : -1;
    auto &dc = context.dc;
    wxRect midiRect = rect;
    GetMidiControlsHorizontalBounds(rect, midiRect);
    NoteTrack::DrawLabelControls
-      ( static_cast<const NoteTrack *>(pTrack), dc, midiRect );
+      ( static_cast<const NoteTrack *>(pTrack), dc, midiRect, channel );
 #endif // EXPERIMENTAL_MIDI_OUT
 }
 

src/tracks/playabletrack/notetrack/ui/NoteTrackButtonHandle.cpp

@@ -24,12 +24,23 @@ NoteTrackButtonHandle::NoteTrackButtonHandle
    : mpTrack{ pTrack }
    , mChannel{ channel }
    , mRect{ rect }
-{}
+{
+   mChangeHighlight = RefreshCode::RefreshCell;
+}
 
 NoteTrackButtonHandle::~NoteTrackButtonHandle()
 {
 }
 
+UIHandle::Result NoteTrackButtonHandle::NeedChangeHighlight
+(const NoteTrackButtonHandle &oldState, const NoteTrackButtonHandle &newState)
+{
+   if (oldState.GetChannel() != newState.GetChannel())
+      // Repaint whenever the highlighted button is different
+      return RefreshCode::RefreshCell;
+   return 0;
+}
+
 UIHandlePtr NoteTrackButtonHandle::HitTest
    (std::weak_ptr<NoteTrackButtonHandle> &holder,
     const wxMouseState &state, const wxRect &rect,

src/tracks/playabletrack/notetrack/ui/NoteTrackButtonHandle.h

@@ -42,6 +42,10 @@ public:
 
    int GetChannel() const { return mChannel; }
 
+   static UIHandle::Result NeedChangeHighlight
+      (const NoteTrackButtonHandle &oldState,
+       const NoteTrackButtonHandle &newState);
+
 protected:
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;