Add implementation for [Get/Set]CornerLabelValue()

Now, every header cell can have a label, including the corner one,
so wxGridHeaderLabelsRenderer::DrawLabel() was moved up one level
in the inheritance chain. Class names were changed accordingly.

Actual storage of corner label is delegated to a grid table class,
just because it is already done that way for column and row labels.

include/wx/generic/grid.h

@@ -325,28 +325,17 @@ protected:
 // wxGridHeaderRenderer and company: like wxGridCellRenderer but for headers
 // ----------------------------------------------------------------------------
 
-// Base class for corner window renderer: it is the simplest of all renderers
+// Base class for header cells renderers.
-// and only has a single function
+class WXDLLIMPEXP_CORE wxGridHeaderCellRenderer
-class WXDLLIMPEXP_CORE wxGridCornerHeaderRenderer
 {
 public:
-    // Draw the border around the corner window.
+    virtual ~wxGridHeaderCellRenderer() {}
+
+    // Draw the border around cell window.
     virtual void DrawBorder(const wxGrid& grid,
                             wxDC& dc,
                             wxRect& rect) const = 0;
 
-    // make the dtor of a class with virtual functions virtual to avoid g++
-    // warnings, even though this class is not supposed to be used
-    // polymorphically
-    virtual ~wxGridCornerHeaderRenderer() { }
-};
-
-
-// Base class for the row/column header cells renderers
-class WXDLLIMPEXP_CORE wxGridHeaderLabelsRenderer
-    : public wxGridCornerHeaderRenderer
-{
-public:
     // Draw header cell label
     virtual void DrawLabel(const wxGrid& grid,
                            wxDC& dc,
@@ -358,16 +347,21 @@ public:
 };
 
 // Currently the row/column/corner renders don't need any methods other than
-// those already in wxGridHeaderLabelsRenderer but still define separate classes
+// those already in wxGridHeaderCellRenderer but still define separate classes
 // for them for future extensions and also for better type safety (i.e. to
 // avoid inadvertently using a column header renderer for the row headers)
 class WXDLLIMPEXP_CORE wxGridRowHeaderRenderer
-    : public wxGridHeaderLabelsRenderer
+    : public wxGridHeaderCellRenderer
 {
 };
 
 class WXDLLIMPEXP_CORE wxGridColumnHeaderRenderer
-    : public wxGridHeaderLabelsRenderer
+    : public wxGridHeaderCellRenderer
+{
+};
+
+class WXDLLIMPEXP_CORE wxGridCornerHeaderRenderer
+    : public wxGridHeaderCellRenderer
 {
 };
 
@@ -745,8 +739,10 @@ public:
 
     virtual wxString GetRowLabelValue( int row );
     virtual wxString GetColLabelValue( int col );
+    virtual wxString GetCornerLabelValue() const;
     virtual void SetRowLabelValue( int WXUNUSED(row), const wxString& ) {}
     virtual void SetColLabelValue( int WXUNUSED(col), const wxString& ) {}
+    virtual void SetCornerLabelValue( const wxString& ) {}
 
     // Attribute handling
     //
@@ -870,8 +866,10 @@ public:
 
     void SetRowLabelValue( int row, const wxString& ) wxOVERRIDE;
     void SetColLabelValue( int col, const wxString& ) wxOVERRIDE;
+    void SetCornerLabelValue( const wxString& ) wxOVERRIDE;
     wxString GetRowLabelValue( int row ) wxOVERRIDE;
     wxString GetColLabelValue( int col ) wxOVERRIDE;
+    wxString GetCornerLabelValue() const wxOVERRIDE;
 
 private:
     wxGridStringArray m_data;
@@ -888,6 +886,8 @@ private:
     wxArrayString     m_rowLabels;
     wxArrayString     m_colLabels;
 
+    wxString m_cornerLabel;
+
     wxDECLARE_DYNAMIC_CLASS_NO_COPY(wxGridStringTable);
 };
 
@@ -1226,6 +1226,7 @@ public:
     int      GetColLabelTextOrientation() const;
     wxString GetRowLabelValue( int row ) const;
     wxString GetColLabelValue( int col ) const;
+    wxString GetCornerLabelValue() const;
 
     wxColour GetCellHighlightColour() const { return m_cellHighlightColour; }
     int      GetCellHighlightPenWidth() const { return m_cellHighlightPenWidth; }
@@ -1250,6 +1251,7 @@ public:
     void     SetColLabelTextOrientation( int textOrientation );
     void     SetRowLabelValue( int row, const wxString& );
     void     SetColLabelValue( int col, const wxString& );
+    void     SetCornerLabelValue( const wxString& );
     void     SetCellHighlightColour( const wxColour& );
     void     SetCellHighlightPenWidth(int width);
     void     SetCellHighlightROPenWidth(int width);

src/generic/grid.cpp

@@ -216,10 +216,10 @@ wxGridCellWorker::~wxGridCellWorker()
 }
 
 // ----------------------------------------------------------------------------
-// wxGridHeaderLabelsRenderer and related classes
+// wxGridHeaderCellRenderer and related classes
 // ----------------------------------------------------------------------------
 
-void wxGridHeaderLabelsRenderer::DrawLabel(const wxGrid& grid,
+void wxGridHeaderCellRenderer::DrawLabel(const wxGrid& grid,
                                          wxDC& dc,
                                          const wxString& value,
                                          const wxRect& rect,
@@ -1167,6 +1167,11 @@ wxString wxGridTableBase::GetColLabelValue( int col )
     return s2;
 }
 
+wxString wxGridTableBase::GetCornerLabelValue() const
+{
+    return wxString{};
+}
+
 wxString wxGridTableBase::GetTypeName( int WXUNUSED(row), int WXUNUSED(col) )
 {
     return wxGRID_VALUE_STRING;
@@ -1600,6 +1605,15 @@ void wxGridStringTable::SetColLabelValue( int col, const wxString& value )
     m_colLabels[col] = value;
 }
 
+void wxGridStringTable::SetCornerLabelValue( const wxString& value )
+{
+    m_cornerLabel = value;
+}
+
+wxString wxGridStringTable::GetCornerLabelValue() const
+{
+    return m_cornerLabel;
+}
 
 //////////////////////////////////////////////////////////////////////
 //////////////////////////////////////////////////////////////////////
@@ -5919,6 +5933,13 @@ void wxGrid::DrawCornerLabel(wxDC& dc)
 {
     wxRect rect(wxSize(m_rowLabelWidth, m_colLabelHeight));
 
+    wxGridCellAttrProvider * const
+        attrProvider = m_table ? m_table->GetAttrProvider() : NULL;
+    const wxGridCornerHeaderRenderer&
+        rend = attrProvider ? attrProvider->GetCornerRenderer()
+                            : static_cast<wxGridCornerHeaderRenderer&>
+                                (gs_defaultHeaderRenderers.cornerRenderer);
+
     if ( m_nativeColumnLabels )
     {
         rect.Deflate(1);
@@ -5930,15 +5951,19 @@ void wxGrid::DrawCornerLabel(wxDC& dc)
         rect.width++;
         rect.height++;
 
-        wxGridCellAttrProvider * const
-            attrProvider = m_table ? m_table->GetAttrProvider() : NULL;
-        const wxGridCornerHeaderRenderer&
-            rend = attrProvider ? attrProvider->GetCornerRenderer()
-                                : static_cast<wxGridCornerHeaderRenderer&>
-                                    (gs_defaultHeaderRenderers.cornerRenderer);
-
         rend.DrawBorder(*this, dc, rect);
     }
+
+    wxString label = GetCornerLabelValue();
+    if( !label.IsEmpty() )
+    {
+        // TODO: add alignment and orientation support for corner window.
+        int hAlign, vAlign;
+        GetColLabelAlignment(&hAlign, &vAlign);
+        const int orient = GetColLabelTextOrientation();
+
+        rend.DrawLabel(*this, dc, label, rect, hAlign, vAlign, orient);
+    }
 }
 
 void wxGrid::DrawColLabel(wxDC& dc, int col)
@@ -7071,6 +7096,18 @@ wxString wxGrid::GetColLabelValue( int col ) const
     }
 }
 
+wxString wxGrid::GetCornerLabelValue() const
+{
+    if ( m_table )
+    {
+        return m_table->GetCornerLabelValue();
+    }
+    else
+    {
+        return wxString{};
+    }
+}
+
 void wxGrid::SetRowLabelSize( int width )
 {
     wxASSERT( width >= 0 || width == wxGRID_AUTOSIZE );
@@ -7299,6 +7336,19 @@ void wxGrid::SetColLabelValue( int col, const wxString& s )
     }
 }
 
+void wxGrid::SetCornerLabelValue( const wxString& s )
+{
+    if ( m_table )
+    {
+        m_table->SetCornerLabelValue( s );
+        if ( !GetBatchCount() )
+        {
+            wxRect rect(wxSize(m_rowLabelWidth, m_colLabelHeight));
+            m_cornerLabelWin->Refresh(true, &rect);
+        }
+    }
+}
+
 void wxGrid::SetGridLineColour( const wxColour& colour )
 {
     if ( m_gridLineColour != colour )