Add 'Select Track' Button.

This is a first take at this new feature.  I'm expecting we'll want to refine it.
https://wiki.audacityteam.org/wiki/Proposal_Select_Track_button_in_TCP has the feature proposal.

src/TrackPanel.cpp

@@ -1379,6 +1379,36 @@ void TrackInfo::MinimizeSyncLockDrawFunction
                     minimized);
    }
 
+   {
+      wxRect bev = rect;
+      GetSelectButtonHorizontalBounds(rect, bev);
+      auto target = dynamic_cast<SelectButtonHandle*>( context.target.get() );
+      bool hit = target && target->GetTrack().get() == pTrack;
+      bool captured = hit && target->IsClicked();
+      bool down = captured && bev.Contains( context.lastState.GetPosition());
+
+      AColor::Bevel2(*dc, !down, bev, selected, hit);
+
+#ifdef EXPERIMENTAL_THEMING
+      wxColour c = theTheme.Colour(clrTrackPanelText);
+      dc->SetBrush(c);
+      dc->SetPen(c);
+#else
+      AColor::Dark(dc, selected);
+#endif
+
+      wxString str = _("Select");
+      wxCoord textWidth;
+      wxCoord textHeight;
+      SetTrackInfoFont(dc);
+      dc->GetTextExtent(str, &textWidth, &textHeight);
+
+      dc->SetTextForeground( c );
+      dc->SetTextBackground( wxTRANSPARENT );
+      dc->DrawText(str, bev.x + 2 + (bev.width-textWidth)/2, bev.y + (bev.height - textHeight) / 2);
+   }
+
+
    // Draw the sync-lock indicator if this track is in a sync-lock selected group.
    if (syncLockSelected)
    {
@@ -2429,7 +2459,8 @@ void TrackInfo::GetMinimizeHorizontalBounds( const wxRect &rect, wxRect &dest )
 
    // Width is rect.width less space on left for track select
    // and on right for sync-lock icon.
-   dest.width = rect.width - (space + syncLockRect.width);
+   dest.width = kTrackInfoBtnSize;
+// rect.width - (space + syncLockRect.width);
 }
 
 void TrackInfo::GetMinimizeRect(const wxRect & rect, wxRect &dest)
@@ -2441,6 +2472,32 @@ void TrackInfo::GetMinimizeRect(const wxRect & rect, wxRect &dest)
    dest.height = results.second;
 }
 
+void TrackInfo::GetSelectButtonHorizontalBounds( const wxRect &rect, wxRect &dest )
+{
+   const int space = 0;// was 3.
+   dest.x = rect.x + space;
+
+   wxRect syncLockRect;
+   GetSyncLockHorizontalBounds( rect, syncLockRect );
+   wxRect minimizeRect;
+   GetMinimizeHorizontalBounds( rect, minimizeRect );
+
+   dest.x = dest.x + space + minimizeRect.width;
+   // Width is rect.width less space on left for track select
+   // and on right for sync-lock icon.
+   dest.width = rect.width - (space + syncLockRect.width) - (space + minimizeRect.width);
+}
+
+
+void TrackInfo::GetSelectButtonRect(const wxRect & rect, wxRect &dest)
+{
+   GetSelectButtonHorizontalBounds( rect, dest );
+   auto results = CalcBottomItemY
+      ( commonTrackTCPBottomLines, kItemMinimize, rect.height);
+   dest.y = rect.y + results.first;
+   dest.height = results.second;
+}
+
 void TrackInfo::GetSyncLockHorizontalBounds( const wxRect &rect, wxRect &dest )
 {
    dest.width = kTrackInfoBtnSize;

src/TrackPanel.h

@@ -182,6 +182,9 @@ namespace TrackInfo
    void GetMinimizeHorizontalBounds( const wxRect &rect, wxRect &dest );
    void GetMinimizeRect(const wxRect & rect, wxRect &dest);
 
+   void GetSelectButtonHorizontalBounds( const wxRect &rect, wxRect &dest );
+   void GetSelectButtonRect(const wxRect & rect, wxRect &dest);
+
    void GetSyncLockHorizontalBounds( const wxRect &rect, wxRect &dest );
    void GetSyncLockIconRect(const wxRect & rect, wxRect &dest);
 

src/tracks/ui/TrackButtonHandles.cpp

@@ -73,6 +73,56 @@ UIHandlePtr MinimizeButtonHandle::HitTest
       return {};
 }
 
+////////////////////////////////////////////////////////////////////////////////
+SelectButtonHandle::SelectButtonHandle
+( const std::shared_ptr<Track> &pTrack, const wxRect &rect )
+   : ButtonHandle{ pTrack, rect }
+{}
+
+SelectButtonHandle::~SelectButtonHandle()
+{
+}
+
+UIHandle::Result SelectButtonHandle::CommitChanges
+(const wxMouseEvent &event, AudacityProject *pProject, wxWindow*)
+{
+   using namespace RefreshCode;
+
+   auto pTrack = mpTrack.lock();
+   if (pTrack)
+   {
+      const bool unsafe = pProject->IsAudioActive();
+      SelectActions::DoListSelection(*pProject,
+         pTrack.get(), event.ShiftDown(), event.ControlDown(), !unsafe);
+//    return RefreshAll ;
+   }
+
+   return RefreshNone;
+}
+
+wxString SelectButtonHandle::Tip(const wxMouseState &) const
+{
+   auto pTrack = GetTrack();
+   return pTrack->GetSelected() ? _("Unselect") : _("Select");
+}
+
+UIHandlePtr SelectButtonHandle::HitTest
+(std::weak_ptr<SelectButtonHandle> &holder,
+ const wxMouseState &state, const wxRect &rect, TrackPanelCell *pCell)
+{
+   wxRect buttonRect;
+   TrackInfo::GetSelectButtonRect(rect, buttonRect);
+
+   if (buttonRect.Contains(state.m_x, state.m_y)) {
+      auto pTrack = static_cast<CommonTrackPanelCell*>(pCell)->FindTrack();
+      auto result = std::make_shared<SelectButtonHandle>( pTrack, buttonRect );
+      result = AssignUIHandlePtr(holder, result);
+      return result;
+   }
+   else
+      return {};
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 CloseButtonHandle::CloseButtonHandle

src/tracks/ui/TrackButtonHandles.h

@@ -40,7 +40,31 @@ public:
 };
 
 ////////////////////////////////////////////////////////////////////////////////
+class SelectButtonHandle final : public ButtonHandle
+{
+   SelectButtonHandle(const SelectButtonHandle&) = delete;
 
+protected:
+   Result CommitChanges
+      (const wxMouseEvent &event, AudacityProject *pProject, wxWindow *pParent)
+      override;
+
+   wxString Tip(const wxMouseState &state) const override;
+
+public:
+   explicit SelectButtonHandle
+      ( const std::shared_ptr<Track> &pTrack, const wxRect &rect );
+
+   SelectButtonHandle &operator=(const SelectButtonHandle&) = default;
+
+   virtual ~SelectButtonHandle();
+
+   static UIHandlePtr HitTest
+      (std::weak_ptr<SelectButtonHandle> &holder,
+       const wxMouseState &state, const wxRect &rect, TrackPanelCell *pCell);
+};
+
+////////////////////////////////////////////////////////////////////////////////
 class CloseButtonHandle final : public ButtonHandle
 {
    CloseButtonHandle(const CloseButtonHandle&) = delete;

src/tracks/ui/TrackControls.cpp

@@ -68,6 +68,10 @@ std::vector<UIHandlePtr> TrackControls::HitTest
       mMinimizeHandle, state, rect, this)))
       results.push_back(result);
 
+   if (NULL != (result = SelectButtonHandle::HitTest(
+      mSelectButtonHandle, state, rect, this)))
+      results.push_back(result);
+
    if (results.empty()) {
       if (NULL != (result = TrackSelectHandle::HitAnywhere(
          mSelectHandle, pTrack)))

src/tracks/ui/TrackControls.h

@@ -20,6 +20,7 @@ class Track;
 class CloseButtonHandle;
 class MenuButtonHandle;
 class MinimizeButtonHandle;
+class SelectButtonHandle;
 class TrackSelectHandle;
 
 class TrackControls /* not final */ : public CommonTrackPanelCell
@@ -60,6 +61,7 @@ protected:
    std::weak_ptr<CloseButtonHandle> mCloseHandle;
    std::weak_ptr<MenuButtonHandle> mMenuHandle;
    std::weak_ptr<MinimizeButtonHandle> mMinimizeHandle;
+   std::weak_ptr<SelectButtonHandle> mSelectButtonHandle;
    std::weak_ptr<TrackSelectHandle> mSelectHandle;
 };