Create and document menu for deleting a strategy in normal forms.

ChangeLog

@@ -29,6 +29,8 @@
   they do not require it. (#80)
 - Clarified handling of .efg/.nfg/.gbt file types in graphical interface and refined warnings about
   unsaved work.  (#12)
+- Created and documented right-click context menu in the normal form pivot table, which makes the
+  mechanism for deleting a strategy more clear.  (#855)
 
 ### Removed
 - Built-in plotting of logit QRE for strategic games has been removed in the GUI (#809)

doc/gui.nfg.rst

@@ -52,7 +52,7 @@ presents such games by hierarchially listing the strategies of one or
 more players on both rows and columns.
 
 The hierarchical presentation of the table is similar to that of a
-contingency table in a spreadsheet application.
+pivot table.
 Here, Alice,
 shown in red, has her strategies listed on the rows of the table, and
 Bob, shown in blue, has his strategies listed on the columns of the
@@ -109,8 +109,8 @@ common convention in print.
 
 
 
-Adding players and strategies
------------------------------
+Changing players and strategies
+-------------------------------
 
 To add an additional player to the game, use the menu item
 :menuselection:`Edit --> Add player`,
@@ -125,6 +125,11 @@ To edit the names of strategies, click on any cell in the strategic
 game table where the strategy label appears, and edit the label using
 the edit control.
 
+Right-clicking a strategy label creates a popup context menu.
+This menu offers the ability to delete the selected strategy
+from the game.  It is not possible to delete a player's only strategy.
+
+
 
 
 Editing payoffs

src/gui/nfgtable.cc

@@ -203,7 +203,21 @@ void RowPlayerWidget::OnCellRightClick(wxSheetEvent &p_event)
   }
 
   const wxSheetCoords coords = p_event.GetCoords();
-  m_table->DeleteRowHeaderStrategy(coords.GetCol(), coords.GetRow());
+  if (IsLabelCell(coords)) {
+    p_event.Skip();
+    return;
+  }
+
+  wxMenu menu;
+  wxMenuItem *deleteItem = menu.Append(wxID_DELETE, _("Delete strategy"));
+  deleteItem->Enable(m_table->CanDeleteRowHeaderStrategy(coords.GetCol(), coords.GetRow()));
+  menu.Bind(
+      wxEVT_MENU,
+      [this, coords](wxCommandEvent &) {
+        m_table->DeleteRowHeaderStrategy(coords.GetCol(), coords.GetRow());
+      },
+      wxID_DELETE);
+  PopupMenu(&menu);
 }
 
 wxString RowPlayerWidget::GetCellValue(const wxSheetCoords &p_coords)
@@ -405,7 +419,23 @@ void ColPlayerWidget::OnCellRightClick(wxSheetEvent &p_event)
   }
 
   const wxSheetCoords coords = p_event.GetCoords();
-  m_table->DeleteColHeaderStrategy(coords.GetRow(), coords.GetCol());
+  if (IsLabelCell(coords)) {
+    p_event.Skip();
+    return;
+  }
+
+  wxMenu menu;
+  wxMenuItem *deleteItem = menu.Append(wxID_DELETE, _("Delete strategy"));
+  deleteItem->Enable(m_table->CanDeleteColHeaderStrategy(coords.GetRow(), coords.GetCol()));
+
+  menu.Bind(
+      wxEVT_MENU,
+      [this, coords](wxCommandEvent &) {
+        m_table->DeleteColHeaderStrategy(coords.GetRow(), coords.GetCol());
+      },
+      wxID_DELETE);
+
+  PopupMenu(&menu);
 }
 
 void ColPlayerWidget::OnUpdate()
@@ -1266,4 +1296,16 @@ GameStrategy TableWidget::GetStrategyByPlayerAndIndex(int player, int strategy)
   return *std::next(strategies.begin(), strategy - 1);
 }
 
+bool TableWidget::CanDeleteRowHeaderStrategy(int headerCol, int) const
+{
+  const int player = GetRowHeaderPlayer(headerCol);
+  return GetSupport().GetStrategies(GetSupport().GetGame()->GetPlayer(player)).size() > 1;
+}
+
+bool TableWidget::CanDeleteColHeaderStrategy(int headerRow, int) const
+{
+  const int player = GetColHeaderPlayer(headerRow);
+  return GetSupport().GetStrategies(GetSupport().GetGame()->GetPlayer(player)).size() > 1;
+}
+
 } // namespace Gambit::GUI

src/gui/nfgtable.h

@@ -423,8 +423,12 @@ class TableWidget final : public wxPanel {
   void RenderGame(wxDC &p_dc, int marginX, int marginY);
   void RenameRowHeaderStrategy(int headerCol, int headerRow, const wxString &value);
   void RenameColHeaderStrategy(int headerRow, int headerCol, const wxString &value);
+
+  bool CanDeleteRowHeaderStrategy(int headerCol, int headerRow) const;
+  bool CanDeleteColHeaderStrategy(int headerRow, int headerCol) const;
   void DeleteRowHeaderStrategy(int headerCol, int headerRow);
   void DeleteColHeaderStrategy(int headerRow, int headerCol);
+
   void SetPayoffCellValue(const wxSheetCoords &coords, const wxString &value);
   //@}
 };