Respect cell alignment when positioning the editors

Define the common logic for positioning editors not taking the entire
cell area (i.e. basically anything other than wxGridCellTextEditor) in
the new DoPositionEditor() function.

Also use the cell and editor alignment to decide where to position the
control if it's smaller than the cell, as it looks better if e.g.
wxGridCellDateEditor appears near the place where the date is displayed
instead of being centered in the middle of a wide column.

include/wx/generic/grid.h

@@ -339,6 +339,16 @@ protected:
     // the dtor is private because only DecRef() can delete us
     virtual ~wxGridCellEditor();
 
+    // Helper for the derived classes positioning the control according to the
+    // attribute alignment if the desired control size is smaller than the cell
+    // size, or centering it vertically if its size is bigger: this looks like
+    // the best compromise when the editor control doesn't fit into the cell.
+    void DoPositionEditor(const wxSize& size,
+                          const wxRect& rectCell,
+                          int hAlign = wxALIGN_LEFT,
+                          int vAlign = wxALIGN_CENTRE_VERTICAL);
+
+
     // the actual window we show on screen (this variable should actually be
     // named m_window, but m_control is kept for backward compatibility)
     wxWindow*  m_control;

src/generic/grideditors.cpp

@@ -331,6 +331,62 @@ void wxGridCellEditor::SetSize(const wxRect& rect)
     m_control->SetSize(rect, wxSIZE_ALLOW_MINUS_ONE);
 }
 
+void wxGridCellEditor::DoPositionEditor(const wxSize& size,
+                                        const wxRect& rectCell,
+                                        int hAlign,
+                                        int vAlign)
+{
+    wxRect rect(rectCell.GetPosition(), size);
+
+    // We center the control around the cell if it doesn't fit into it in one
+    // or both of directions, as this seems to look the best (difference is
+    // typically relatively small and by centering it, we divide it by two on
+    // each side, making it even smaller).
+    //
+    // For now just remember in which direction to do it in this variable and
+    // then do it at the end.
+    int centerDir = 0;
+
+    // We're only going to need the alignment if the control is smaller than
+    // the cell in at least one direction.
+    if ( size.x < rectCell.width || size.y < rectCell.height )
+    {
+        if ( GetCellAttr() )
+            GetCellAttr()->GetNonDefaultAlignment(&hAlign, &vAlign);
+    }
+
+    if ( size.x < rectCell.width )
+    {
+        if ( hAlign == wxALIGN_CENTER_HORIZONTAL )
+            centerDir |= wxHORIZONTAL;
+        else if ( hAlign == wxALIGN_RIGHT )
+            rect.x = rectCell.x + rectCell.width - rect.width;
+        //else: nothing to do for the left alignment
+    }
+    else
+    {
+        centerDir |= wxHORIZONTAL;
+    }
+
+    if ( size.y < rectCell.height )
+    {
+        if ( vAlign == wxALIGN_CENTRE_VERTICAL )
+            centerDir |= wxVERTICAL;
+        else if ( vAlign == wxALIGN_BOTTOM )
+            rect.y = rectCell.y + rectCell.height - rect.height;
+        //else: nothing to do for the top alignment
+    }
+    else
+    {
+        centerDir |= wxVERTICAL;
+    }
+
+    if ( centerDir )
+        rect = rect.CenterIn(rectCell, centerDir);
+
+    wxGridCellEditor::SetSize(rect);
+}
+
 void wxGridCellEditor::HandleReturn(wxKeyEvent& event)
 {
     event.Skip();
@@ -695,9 +751,7 @@ void wxGridCellNumberEditor::SetSize(const wxRect& rectCell)
         if ( size.y <= 0 )
             size.y = rectCell.GetHeight();
 
-        wxRect rectSpin(rectCell.GetPosition(), size);
-
-        wxGridCellEditor::SetSize(rectSpin.CenterIn(rectCell, wxVERTICAL));
+        DoPositionEditor(size, rectCell);
     }
     else
 #endif // wxUSE_SPINCTRL
@@ -1446,9 +1500,7 @@ void wxGridCellChoiceEditor::SetSize(const wxRect& rect)
     if ( size.x < rect.width )
         size.x = rect.width;
 
-    wxRect rectChoice(rect.GetPosition(), size);
-
-    wxGridCellEditor::SetSize(rectChoice.CenterIn(rect, wxVERTICAL));
+    DoPositionEditor(size, rect);
 }
 
 void wxGridCellChoiceEditor::BeginEdit(int row, int col, wxGrid* grid)
@@ -1759,19 +1811,18 @@ void wxGridCellDateEditor::SetSize(const wxRect& r)
 {
     wxASSERT_MSG(m_control, "The wxGridCellDateEditor must be created first!");
 
-    const wxSize bestSize = DatePicker()->GetBestSize();
-
-    wxRect rect(r.GetPosition(), bestSize);
+    wxSize size = DatePicker()->GetBestSize();
 
     // Allow date picker to become a bit wider, if necessary, but not too wide,
     // otherwise it just looks ugly.
-    if ( r.GetWidth() > bestSize.GetWidth()
-            && r.GetWidth() < 3*bestSize.GetWidth()/2 )
+    if ( r.GetWidth() > size.GetWidth()
+            && r.GetWidth() < 3*size.GetWidth()/2 )
     {
-        rect.SetWidth(r.GetWidth());
+        size.x = r.GetWidth();
     }
 
-    wxGridCellEditor::SetSize(rect.CenterIn(r, wxVERTICAL));
+    // Use right alignment by default for consistency with the date renderer.
+    DoPositionEditor(size, r, wxALIGN_RIGHT);
 }
 
 void wxGridCellDateEditor::BeginEdit(int row, int col, wxGrid* grid)