Demonstrate intensive attribute usage in grid sample

Add options to fill grid either half (checkered cells) or fully (all
cells coloured) with attributes. Available from Grid > "Toggle Checkered
Cells" and "Toggle Coloured Cells".

samples/grid/griddemo.cpp

@@ -293,6 +293,8 @@ wxBEGIN_EVENT_TABLE( GridFrame, wxFrame )
     EVT_MENU( ID_AUTOSIZECOLS, GridFrame::AutoSizeCols )
     EVT_MENU( ID_CELLOVERFLOW, GridFrame::CellOverflow )
     EVT_MENU( ID_RESIZECELL, GridFrame::ResizeCell )
+    EVT_MENU( ID_TOGGLE_CHECKERED_CELLS, GridFrame::ToggleCheckeredCells )
+    EVT_MENU( ID_TOGGLE_COLOURED_CELLS, GridFrame::ToggleColouredCells )
     EVT_MENU( ID_SETLABELCOLOUR, GridFrame::SetLabelColour )
     EVT_MENU( ID_SETLABELTEXTCOLOUR, GridFrame::SetLabelTextColour )
     EVT_MENU( ID_SETLABEL_FONT, GridFrame::SetLabelFont )
@@ -443,6 +445,10 @@ GridFrame::GridFrame()
     viewMenu->AppendCheckItem(ID_AUTOSIZECOLS, "&Auto-size cols");
     viewMenu->AppendCheckItem(ID_CELLOVERFLOW, "&Overflow cells");
     viewMenu->AppendCheckItem(ID_RESIZECELL, "&Resize cell (7,1)");
+    viewMenu->AppendCheckItem(ID_TOGGLE_CHECKERED_CELLS,
+                              "Toggle Chec&kered Cells\tCtrl+Shift+K");
+    viewMenu->AppendCheckItem(ID_TOGGLE_COLOURED_CELLS,
+                              "Toggle Co&loured Cells\tCtrl+Shift+L");
     viewMenu->Append(ID_HIDECOL, "&Hide column A");
     viewMenu->Append(ID_SHOWCOL, "&Show column A");
     viewMenu->Append(ID_HIDEROW, "&Hide row 2");
@@ -2850,3 +2856,86 @@ void GridFrame::ShowRow( wxCommandEvent& WXUNUSED(event) )
 {
     grid->ShowRow(1);
 }
+
+namespace
+{
+
+// Toggle status of either checkered or coloured cells in the grid.
+// Note that, for shared attribute testing purposes, with checkered cells
+// a cell's complete attribute is destructively overwritten (except merged
+// cells which are skipped). While with coloured cells only the background
+// colour changes.
+void ToggleGridCells(wxGrid* grid, bool useCheckered)
+{
+    static bool s_checkeredOn, s_colouredOn;
+    if ( useCheckered )
+        s_checkeredOn = !s_checkeredOn;
+    else
+        s_colouredOn = !s_colouredOn;
+
+    wxGridCellAttrPtr attr;
+    if ( useCheckered && s_checkeredOn )
+    {
+        attr = wxGridCellAttrPtr(new wxGridCellAttr);
+        attr->SetBackgroundColour(*wxLIGHT_GREY);
+    }
+
+    wxColour bgCol = grid->GetDefaultCellBackgroundColour();
+
+    for ( int row = 0; row < grid->GetNumberRows(); ++row )
+    {
+        for ( int col = 0; col < grid->GetNumberCols(); ++col )
+        {
+            if ( useCheckered && (row ^ col) & 1 )
+                continue;
+
+            // Skip overwriting attributes of merged cells.
+            int rows, cols;
+            if ( useCheckered
+                 && grid->GetCellSize(row, col, &rows, &cols)
+                    != wxGrid::CellSpan_None )
+            {
+                continue;
+            }
+
+            if ( useCheckered )
+            {
+                grid->SetAttr(row, col, attr.get());
+
+                if ( s_checkeredOn )
+                    attr->IncRef();
+            }
+            else
+            {
+                if ( s_colouredOn )
+                {
+                    const int factor = 256 / 64;
+                    unsigned char r, g, b;
+                    r = (127 + row * factor + col / factor) & 0xff;
+                    g = (col * factor + row / (factor * 2)) & 0xff;
+                    b = ((row ^ col) * factor) & 0xff;
+
+                    bgCol.Set(r < 128 ? r * 2 : 255 - r * 2,
+                              g < 128 ? g * 2 : 255 - g * 2,
+                              b < 128 ? b * 2 : 255 - b * 2);
+                }
+
+                grid->SetCellBackgroundColour(row, col, bgCol);
+            }
+        }
+    }
+
+    grid->Refresh();
+}
+
+} // anoymous namespace
+
+void GridFrame::ToggleCheckeredCells( wxCommandEvent& WXUNUSED(event) )
+{
+    ToggleGridCells(grid, /* useCheckered = */ true);
+}
+
+void GridFrame::ToggleColouredCells( wxCommandEvent& WXUNUSED(event) )
+{
+    ToggleGridCells(grid, /* useCheckered = */ false);
+}

samples/grid/griddemo.h

@@ -49,6 +49,8 @@ class GridFrame : public wxFrame
     void AutoSizeCols( wxCommandEvent& );
     void CellOverflow( wxCommandEvent& );
     void ResizeCell( wxCommandEvent& );
+    void ToggleCheckeredCells( wxCommandEvent& );
+    void ToggleColouredCells( wxCommandEvent& );
     void SetLabelColour( wxCommandEvent& );
     void SetLabelTextColour( wxCommandEvent& );
     void SetLabelFont(wxCommandEvent &);
@@ -153,6 +155,8 @@ public:
         ID_TOGGLEGRIDLINES,
         ID_AUTOSIZECOLS,
         ID_CELLOVERFLOW,
+        ID_TOGGLE_CHECKERED_CELLS,
+        ID_TOGGLE_COLOURED_CELLS,
         ID_HIDECOL,
         ID_SHOWCOL,
         ID_HIDEROW,