Add wxGridCellActivatableEditor and show it in the grid sample

Add a helper class making it easier to define activation-only editors
and use it to implement MyGridStarEditor in the sample, showing a
typical example of using such editor.

samples/grid/griddemo.cpp

@@ -121,6 +121,135 @@ private:
     wxDECLARE_NO_COPY_CLASS(CustomColumnHeadersProvider);
 };
 
+// ----------------------------------------------------------------------------
+// Custom wxGrid renderer and editor for showing stars as used for rating
+// ----------------------------------------------------------------------------
+
+// Max number of stars shown by MyGridStarRenderer.
+static const int MAX_STARS = 5;
+
+// Helper function returning the number between 0 and MAX_STARS corresponding
+// to the value of the cell.
+static int GetStarValue(wxGrid& grid, int row, int col)
+{
+    unsigned long n = 0;
+    if ( !grid.GetCellValue(row, col).ToULong(&n) || n > MAX_STARS )
+        n = 0;
+
+    return static_cast<int>(n);
+}
+
+// Another helper returning the string containing the appropriate number of
+// black and white stars.
+static wxString GetStarString(int numBlackStars)
+{
+    const wxUniChar BLACK_STAR = 0x2605;
+    const wxUniChar WHITE_STAR = 0x2606;
+
+    return wxString(BLACK_STAR, numBlackStars) +
+            wxString(WHITE_STAR, MAX_STARS - numBlackStars);
+}
+
+// Renders the value of the cell, which is supposed to be a number between 1
+// and 5, as a sequence of that number of black stars followed by the number of
+// white stars needed to have 5 stars in total.
+class MyGridStarRenderer : public wxGridCellRenderer
+{
+public:
+    virtual void Draw(wxGrid& grid,
+                      wxGridCellAttr& attr,
+                      wxDC& dc,
+                      const wxRect& rect,
+                      int row, int col,
+                      bool isSelected) wxOVERRIDE
+    {
+        wxGridCellRenderer::Draw(grid, attr, dc, rect, row, col, isSelected);
+
+        grid.DrawTextRectangle(dc, GetStarString(GetStarValue(grid, row, col)),
+                               rect, attr);
+    }
+
+    virtual wxSize GetBestSize(wxGrid& WXUNUSED(grid),
+                               wxGridCellAttr& attr,
+                               wxDC& dc,
+                               int WXUNUSED(row),
+                               int WXUNUSED(col)) wxOVERRIDE
+    {
+        dc.SetFont(attr.GetFont());
+        return dc.GetTextExtent(GetStarString(MAX_STARS));
+    }
+
+    virtual wxGridCellRenderer *Clone() const wxOVERRIDE
+    {
+        return new MyGridStarRenderer();
+    }
+};
+
+// Activatable editor cycling the number of stars on each activation.
+class MyGridStarEditor : public wxGridCellActivatableEditor
+{
+public:
+    virtual wxGridActivationResult
+    TryActivate(int row, int col, wxGrid* grid,
+                const wxGridActivationSource& actSource) wxOVERRIDE
+    {
+        int numStars = -1;
+
+        switch ( actSource.GetOrigin() )
+        {
+            case wxGridActivationSource::Program:
+                // It isn't really possible to programmatically start editing a
+                // cell using this editor.
+                return wxGridActivationResult::DoNothing();
+
+            case wxGridActivationSource::Key:
+                switch ( actSource.GetKeyEvent().GetKeyCode() )
+                {
+                    case '0': numStars = 0; break;
+                    case '1': numStars = 1; break;
+                    case '2': numStars = 2; break;
+                    case '3': numStars = 3; break;
+                    case '4': numStars = 4; break;
+                    case '5': numStars = 5; break;
+                    case ' ':
+                        // Use space key to cycle over the values.
+                        break;
+
+                    default:
+                        return wxGridActivationResult::DoNothing();
+                }
+
+                break;
+
+            case wxGridActivationSource::Mouse:
+                // Ideally we should use the mouse event position to determine
+                // on which star the user clicked, but for now keep it simple
+                // and just cycle through the star value.
+                break;
+        }
+
+        if ( numStars == -1 )
+            numStars = (GetStarValue(*grid, row, col) + 1) % (MAX_STARS + 1);
+
+        m_value.Printf("%d", numStars);
+
+        return wxGridActivationResult::DoChange(m_value);
+    }
+
+    virtual void DoActivate(int row, int col, wxGrid* grid) wxOVERRIDE
+    {
+        grid->SetCellValue(row, col, m_value);
+    }
+
+    virtual wxGridCellEditor *Clone() const
+    {
+        return new MyGridStarEditor();
+    }
+
+private:
+    wxString m_value;
+};
+
 // ----------------------------------------------------------------------------
 // wxWin macros
 // ----------------------------------------------------------------------------
@@ -517,6 +646,10 @@ GridFrame::GridFrame()
     grid->SetCellAlignment(4, 4, wxALIGN_CENTRE, wxALIGN_CENTRE);
     grid->SetCellRenderer(4, 4, new MyGridCellRenderer);
 
+    grid->SetCellValue(4, 5, "3");
+    grid->SetCellRenderer(4, 5, new MyGridStarRenderer);
+    grid->SetCellEditor(4, 5, new MyGridStarEditor);
+
     grid->SetCellRenderer(3, 0, new wxGridCellBoolRenderer);
     grid->SetCellEditor(3, 0, new wxGridCellBoolEditor);
     grid->SetCellBackgroundColour(3, 0, wxColour(255, 127, 127));