implement wxListBox::EnsureVisible() in wxGTK; add a test for it to the widgets sample

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@51659 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -139,6 +139,7 @@ wxGTK:
 
 - Return false from wxEventLoop::Dispatch() if gtk_main_quit() was called and
   so the loop should exit (Rodolfo Schulz de Lima).
+- Implement wxListBox::EnsureVisible() (Andreas Kling)
 - Fixed wxCURSOR_HAND to map to GDK_HAND2 and not GDK_HAND1, for consistency
   with other applications.
 

include/wx/gtk/listbox.h

@@ -74,6 +74,8 @@ public:
     virtual int GetSelection() const;
     virtual int GetSelections(wxArrayInt& aSelections) const;
 
+    virtual void EnsureVisible(int n);
+
     static wxVisualAttributes
     GetClassDefaultAttributes(wxWindowVariant variant = wxWINDOW_VARIANT_NORMAL);
 
@@ -119,6 +121,9 @@ protected:
 private:
     void Init(); //common construction
 
+    // common part of DoSetFirstItem() and EnsureVisible()
+    void DoScrollToCell(int n, float alignY, float alignX);
+
     DECLARE_DYNAMIC_CLASS(wxListBox)
 };
 

src/gtk/listbox.cpp

@@ -906,7 +906,7 @@ void wxListBox::GtkSetSelection(int n, const bool select, const bool blockEvent)
     m_blockEvent = false;
 }
 
-void wxListBox::DoSetFirstItem( int n )
+void wxListBox::DoScrollToCell(int n, float alignY, float alignX)
 {
     wxCHECK_RET( m_treeview, wxT("invalid listbox") );
     wxCHECK_RET( IsValid(n), wxT("invalid index"));
@@ -928,11 +928,21 @@ void wxListBox::DoSetFirstItem( int n )
 
     // Scroll to the desired cell (0.0 == topleft alignment)
     gtk_tree_view_scroll_to_cell(m_treeview, path, NULL,
-                                 TRUE, 0.0f, 0.0f);
+                                 TRUE, alignY, alignX);
 
     gtk_tree_path_free(path);
 }
 
+void wxListBox::DoSetFirstItem(int n)
+{
+    DoScrollToCell(n, 0, 0);
+}
+
+void wxListBox::EnsureVisible(int n)
+{
+    DoScrollToCell(n, 0.5, 0);
+}
+
 // ----------------------------------------------------------------------------
 // hittest
 // ----------------------------------------------------------------------------