Make it possible to combine wxEXPAND and alignment in wxGridSizer.

Allow overriding wxEXPAND effect in one of the directions by specifying
wxALIGN_{RIGHT,BOTTOM} or wxALIGN_CENTRE_{HORIZONTAL,VERTICAL} together with
it (unfortunately this doesn't work for wxALIGN_{LEFT,TOP} as their value is 0
and so their presence in flags can't be detected).

interface/wx/sizer.h

@@ -68,7 +68,17 @@
              These flags are used to specify which side(s) of the sizer item
              the border width will apply to.}
     @itemdef{wxEXPAND,
-             The item will be expanded to fill the space assigned to the item.}
+             The item will be expanded to fill the space assigned to the item.
+             When used for the items of wxBoxSizer, the expansion only happens
+             in the transversal direction of the sizer as only the item
+             proportion governs its behaviour in the principal sizer direction.
+             But when it is used for the items of wxGridSizer, this flag can be
+             combined with the alignment flags which override it in the
+             corresponding direction if specified, e.g. @c wxEXPAND |
+             wxALIGN_CENTRE_VERTICAL would expand the item only horizontally
+             but center it vertically. Notice that this doesn't work for the
+             default left/top alignment and @c wxEXPAND still applies in both
+             directions if it is combined with @c wxALIGN_LEFT or @c wxALIGN_TOP.}
     @itemdef{wxSHAPED,
              The item will be expanded as much as possible while also
              maintaining its aspect ratio.}

src/common/sizer.cpp

@@ -1517,11 +1517,13 @@ void wxGridSizer::SetItemBounds( wxSizerItem *item, int x, int y, int w, int h )
     wxSize sz( item->GetMinSizeWithBorder() );
     int flag = item->GetFlag();
 
-    if ((flag & wxEXPAND) || (flag & wxSHAPED))
+    // wxSHAPED maintains aspect ratio and so always applies to both
+    // directions.
+    if ( flag & wxSHAPED )
     {
-       sz = wxSize(w, h);
+        sz = wxSize(w, h);
     }
-    else
+    else // Otherwise we handle each direction individually.
     {
         if (flag & wxALIGN_CENTER_HORIZONTAL)
         {
@@ -1531,6 +1533,10 @@ void wxGridSizer::SetItemBounds( wxSizerItem *item, int x, int y, int w, int h )
         {
             pt.x = x + (w - sz.x);
         }
+        else if (flag & wxEXPAND)
+        {
+            sz.x = w;
+        }
 
         if (flag & wxALIGN_CENTER_VERTICAL)
         {
@@ -1540,6 +1546,10 @@ void wxGridSizer::SetItemBounds( wxSizerItem *item, int x, int y, int w, int h )
         {
             pt.y = y + (h - sz.y);
         }
+        else if ( flag & wxEXPAND )
+        {
+            sz.y = h;
+        }
     }
 
     item->SetDimension(pt, sz);

tests/sizers/gridsizer.cpp

@@ -136,4 +136,23 @@ void GridSizerTestCase::Expand()
     CPPUNIT_ASSERT_EQUAL( wxSize(sizeChild.x, sizeRest.y),
                           children[2]->GetSize() );
     CPPUNIT_ASSERT_EQUAL( sizeRest, children[3]->GetSize() );
+
+    // With expand and another alignment flag, they should expand only in the
+    // direction in which the alignment is not given.
+    SetChildren(children, wxSizerFlags().Expand().CentreVertical());
+    CPPUNIT_ASSERT_EQUAL( sizeChild, children[0]->GetSize() );
+    CPPUNIT_ASSERT_EQUAL( wxSize(sizeRest.x, sizeChild.y),
+                          children[1]->GetSize() );
+    CPPUNIT_ASSERT_EQUAL( sizeChild, children[2]->GetSize() );
+    CPPUNIT_ASSERT_EQUAL( wxSize(sizeRest.x, sizeChild.y),
+                          children[3]->GetSize() );
+
+    // Same as above but mirrored.
+    SetChildren(children, wxSizerFlags().Expand().CentreHorizontal());
+    CPPUNIT_ASSERT_EQUAL( sizeChild, children[0]->GetSize() );
+    CPPUNIT_ASSERT_EQUAL( sizeChild, children[1]->GetSize() );
+    CPPUNIT_ASSERT_EQUAL( wxSize(sizeChild.x, sizeRest.y),
+                          children[2]->GetSize() );
+    CPPUNIT_ASSERT_EQUAL( wxSize(sizeChild.x, sizeRest.y),
+                          children[3]->GetSize() );
 }