Add two commands to move the cursor/selection to next/prev label

The two commands are "selection to next label" and "selection to previous label".
They have default shortcuts alt+right and alt+left.

A label track does not have to be the focus. If there is a single label track in the project, that it used. If there is more than one label track, then the first label track, if any, starting at the focused track is used.

If the commands are used during playback of the project, playback continues from the new cursor/selection.

The commands provide feedback to screen readers: the name of the label, and position in the form of "i of n".

src/LabelTrack.cpp

@@ -105,7 +105,8 @@ LabelTrack::LabelTrack(const std::shared_ptr<DirManager> &projDirManager):
    mMouseOverLabelRight(-1),
    mRestoreFocus(-1),
    mClipLen(0.0),
-   mIsAdjustingLabel(false)
+   mIsAdjustingLabel(false),
+   miLastLabel(-1)
 {
    SetDefaultName(_("Label Track"));
    SetName(GetDefaultName());
@@ -2849,3 +2850,55 @@ wxString LabelTrack::GetTextOfLabels(double t0, double t1) const
 
    return retVal;
 }
+
+int LabelTrack::FindNextLabel(const SelectedRegion& currentRegion)
+{
+   int i = -1;
+
+   if (!mLabels.empty()) {
+      int len = (int) mLabels.size();
+      if (miLastLabel >= 0 && miLastLabel + 1 < len
+         && currentRegion.t0() == mLabels[miLastLabel].getT0()
+         && currentRegion.t0() == mLabels[miLastLabel + 1].getT0() ) {
+         i = miLastLabel + 1;
+      }
+      else {
+         i = 0;
+         if (currentRegion.t0() < mLabels[len - 1].getT0()) {
+            while (i < len &&
+                  mLabels[i].getT0() <= currentRegion.t0()) {
+               i++;
+            }
+         }
+      }
+   }
+
+   miLastLabel = i;
+   return i;
+}
+
+ int LabelTrack::FindPrevLabel(const SelectedRegion& currentRegion)
+{
+   int i = -1;
+
+   if (!mLabels.empty()) {
+      int len = (int) mLabels.size();
+      if (miLastLabel > 0 && miLastLabel < len
+         && currentRegion.t0() == mLabels[miLastLabel].getT0()
+         && currentRegion.t0() == mLabels[miLastLabel - 1].getT0() ) {
+         i = miLastLabel - 1;
+      }
+      else {
+         i = len - 1;
+         if (currentRegion.t0() > mLabels[0].getT0()) {
+            while (i >=0  &&
+                  mLabels[i].getT0() >= currentRegion.t0()) {
+               i--;
+            }
+         }
+      }
+   }
+
+   miLastLabel = i;
+   return i;
+}

src/LabelTrack.h

@@ -232,6 +232,9 @@ class AUDACITY_DLL_API LabelTrack final : public Track
    // Returns tab-separated text of all labels completely within given region
    wxString GetTextOfLabels(double t0, double t1) const;
 
+   int FindNextLabel(const SelectedRegion& currentSelection);
+   int FindPrevLabel(const SelectedRegion& currentSelection);
+
  public:
    void SortLabels();
    //These two are used by a TrackPanel KLUDGE, which is why they are public.
@@ -268,6 +271,8 @@ class AUDACITY_DLL_API LabelTrack final : public Track
    // Set in copied label tracks
    double mClipLen;
 
+   int miLastLabel;                 // used by FindNextLabel and FindPrevLabel
+
    void ComputeLayout(const wxRect & r, const ZoomInfo &zoomInfo) const;
    void ComputeTextPosition(const wxRect & r, int index) const;
 

src/Menus.cpp

@@ -1251,6 +1251,11 @@ void AudacityProject::CreateMenusAndCommands()
    c->AddCommand(wxT("PlaySpeedInc"), _("Increase playback speed"), FN(OnPlaySpeedInc));
    c->AddCommand(wxT("PlaySpeedDec"), _("Decrease playback speed"), FN(OnPlaySpeedDec));
 
+   c->AddCommand(wxT("SelToNextLabel"), _("Selection to next label"), FN(OnSelToNextLabel), wxT("Alt+Right"),
+      CaptureNotBusyFlag | TrackPanelHasFocus, CaptureNotBusyFlag | TrackPanelHasFocus);
+   c->AddCommand(wxT("SelToPrevLabel"), _("Selection to previous label"), FN(OnSelToPrevLabel), wxT("Alt+Left"),
+      CaptureNotBusyFlag | TrackPanelHasFocus, CaptureNotBusyFlag | TrackPanelHasFocus);
+
 #ifdef __WXMAC__
    /* i8n-hint: Shrink all project windows to icons on the Macintosh tooldock */
    c->AddCommand(wxT("MacMinimizeAll"), _("Minimize all projects"),
@@ -2656,6 +2661,72 @@ void AudacityProject::OnSelToEnd()
    ModifyState(false);
 }
 
+void AudacityProject::OnSelToNextLabel()
+{
+   OnSelToLabel(true);
+}
+
+void AudacityProject::OnSelToPrevLabel()
+{
+   OnSelToLabel(false);
+}
+
+void AudacityProject::OnSelToLabel(bool next)
+{
+   // Find the number of label tracks, and ptr to last track found
+   Track* track = nullptr;
+   int nLabelTrack = 0;
+   TrackListOfKindIterator iter(Track::Label, &*mTracks);
+   for (Track* t = iter.First(); t; t = iter.Next()) {
+      nLabelTrack++;
+      track = t;
+   }
+
+   if (nLabelTrack == 0 ) {
+      mTrackPanel->MessageForScreenReader(_("no label track"));
+   }
+   else if (nLabelTrack > 1) {         // find first label track, if any, starting at the focused track
+      track = mTrackPanel->GetFocusedTrack();
+      while (track && track->GetKind() != Track::Label) {
+         track = mTracks->GetNext(track, true);
+         if (!track) {
+          mTrackPanel->MessageForScreenReader(_("no label track at or below focused track"));
+         }
+      }
+   }
+
+   // If there is a single label track, or there is a label track at or below the focused track
+   if (track) {
+      LabelTrack* lt = static_cast<LabelTrack*>(track);
+      int i;
+      if (next)
+         i = lt->FindNextLabel(GetSelection());
+      else
+         i = lt->FindPrevLabel(GetSelection());
+
+      if (i >= 0) {
+         const LabelStruct* label = lt->GetLabel(i);
+         if (IsAudioActive()) {
+            OnPlayStop();     // stop
+            GetViewInfo().selectedRegion = label->selectedRegion;
+            RedrawProject();
+            OnPlayStop();     // play
+         }
+         else {
+            GetViewInfo().selectedRegion = label->selectedRegion;
+            RedrawProject();
+         }
+
+         wxString message;
+         message.Printf(wxT("%s %d of %d"), label->title, i + 1, lt->GetNumLabels() );
+         mTrackPanel->MessageForScreenReader(message);
+      }
+      else {
+         mTrackPanel->MessageForScreenReader(_("no labels in label track"));
+      }
+   }
+}
+
 void AudacityProject::OnCursorUp()
 {
    mTrackPanel->OnPrevTrack( false );

src/Menus.h

@@ -170,6 +170,10 @@ void OnSetRightSelection();
 void OnSelToStart();
 void OnSelToEnd();
 
+void OnSelToNextLabel();
+void OnSelToPrevLabel();
+void OnSelToLabel(bool next);
+
 void OnZeroCrossing();
 
 void OnLockPlayRegion();

src/TrackPanel.cpp

@@ -2406,6 +2406,12 @@ void TrackPanel::UpdateAccessibility()
       mAx->Updated();
 }
 
+void TrackPanel::MessageForScreenReader(const wxString& message)
+{
+   if (mAx)
+      mAx->MessageForScreenReader(message);
+}
+
 #ifdef EXPERIMENTAL_SPECTRAL_EDITING
 namespace {
    

src/TrackPanel.h

@@ -308,6 +308,7 @@ protected:
 
 public:
    virtual void UpdateAccessibility();
+   void MessageForScreenReader(const wxString& message);
 
 #ifdef EXPERIMENTAL_SPECTRAL_EDITING
 public:

src/TrackPanelAx.cpp

@@ -37,6 +37,9 @@ TrackPanelAx::TrackPanelAx( wxWindow *window )
 {
    mTrackPanel = wxDynamicCast( window, TrackPanel );
    mFocusedTrack = NULL;
+
+   mTrackName = true;
+   mMessageCount = 0;
 }
 
 TrackPanelAx::~TrackPanelAx()
@@ -62,8 +65,11 @@ Track *TrackPanelAx::GetFocus()
 // Changes focus to a specified track
 void TrackPanelAx::SetFocus( Track *track )
 {
+   mTrackName = true;
+
 #if wxUSE_ACCESSIBILITY
-   if( mFocusedTrack != NULL )
+
+   if( mFocusedTrack != NULL && !mFocusedTrack->GetSelected() )
    {
       NotifyEvent( wxACC_EVENT_OBJECT_SELECTIONREMOVE,
                    mTrackPanel,
@@ -164,6 +170,7 @@ void TrackPanelAx::Updated()
 {
 #if wxUSE_ACCESSIBILITY
    Track *t = GetFocus();
+   mTrackName = true;
 
    // logically, this should be an OBJECT_NAMECHANGE event, but Window eyes 9.1
    // does not read out the name with this event type, hence use OBJECT_FOCUS.
@@ -174,6 +181,32 @@ void TrackPanelAx::Updated()
 #endif
 }
 
+void TrackPanelAx::MessageForScreenReader(const wxString& message)
+{
+#if wxUSE_ACCESSIBILITY
+   if (mTrackPanel == wxWindow::FindFocus())
+   {
+      Track *t = GetFocus();
+      int childId = t ? TrackNum(t) : 0;
+
+      mMessage = message;
+
+      // append \a alernatively, so that the string is never the same as the previous string.
+      // This ensures that screen readers read it.
+      if (mMessageCount % 2 == 0)
+         mMessage.Append('\a');
+      mMessageCount++;
+
+      mTrackName = false;
+      NotifyEvent(wxACC_EVENT_OBJECT_FOCUS,
+               mTrackPanel,
+               wxOBJID_CLIENT,
+               childId);
+   }
+
+#endif
+}
+
 #if wxUSE_ACCESSIBILITY
 
 // Retrieves the address of an IDispatch interface for the specified child.
@@ -285,6 +318,8 @@ wxAccStatus TrackPanelAx::GetLocation( wxRect& rect, int elementId )
 wxAccStatus TrackPanelAx::GetName( int childId, wxString* name )
 {
 #if defined(__WXMSW__) || defined(__WXMAC__)
+   if (mTrackName)
+   {
       if( childId == wxACC_SELF )
       {
          *name = _( "TrackView" );
@@ -361,6 +396,11 @@ wxAccStatus TrackPanelAx::GetName( int childId, wxString* name )
             }
          }
       }
+   }
+   else
+   {
+      *name = mMessage;
+   }
 
    return wxACC_OK;
 #endif
@@ -374,6 +414,8 @@ wxAccStatus TrackPanelAx::GetName( int childId, wxString* name )
 wxAccStatus TrackPanelAx::GetRole( int childId, wxAccRole* role )
 {
 #if defined(__WXMSW__)
+   if (mTrackName)
+   {
       if( childId == wxACC_SELF )
       {
          *role = wxROLE_SYSTEM_TABLE;
@@ -382,6 +424,11 @@ wxAccStatus TrackPanelAx::GetRole( int childId, wxAccRole* role )
       {
          *role = wxROLE_SYSTEM_ROW;
       }
+   }
+   else
+   {
+      *role = wxROLE_NONE;
+   }
 #endif
 
 #if defined(__WXMAC__)
@@ -427,7 +474,7 @@ wxAccStatus TrackPanelAx::GetState( int childId, long* state )
             *state |= wxACC_STATE_SYSTEM_FOCUSED;
          }
 
-         if( t->GetSelected() )
+         if( t->GetSelected() && mTrackName )
          {
             *state |= wxACC_STATE_SYSTEM_SELECTED;
          }

src/TrackPanelAx.h

@@ -41,6 +41,8 @@ public:
    // Called to signal changes to a track
    void Updated();
 
+   void MessageForScreenReader(const wxString& message);
+
 #if wxUSE_ACCESSIBILITY
    // Retrieves the address of an IDispatch interface for the specified child.
    // All objects must support this property.
@@ -108,6 +110,10 @@ private:
 
    TrackPanel *mTrackPanel;
    Track *mFocusedTrack;
+
+   wxString mMessage;
+   bool mTrackName;
+   int mMessageCount;
 };
 
 #endif // __AUDACITY_TRACK_PANEL_ACCESSIBILITY__