Add wxDataViewCtrl::{Set,Get}CurrentItem().

Current item is the same as the selected item in single selection mode but in
multiple selection mode there was no way to neither get this item nor change
it before so add the new functions to allow doing this now.

The new methods are implemented for the generic, GTK and OS X/Cocoa versions
but only stubs are provided for OS X/Carbon.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65228 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/dataview.cpp

@@ -96,6 +96,97 @@ private:
     wxDECLARE_NO_COPY_CLASS(wxGtkTreePath);
 };
 
+// ----------------------------------------------------------------------------
+// wxGtkTreeSelectionLock: prevent selection from changing during the
+//                                 lifetime of this object
+// ----------------------------------------------------------------------------
+
+// Implementation note: it could be expected that setting the selection
+// function in this class ctor and resetting it back to the old value in its
+// dtor would work. However currently gtk_tree_selection_get_select_function()
+// can't be passed NULL (see https://bugzilla.gnome.org/show_bug.cgi?id=626276)
+// so we can't do this. Instead, we always use the selection function (which
+// imposes extra overhead, albeit minimal one, on all selection operations) and
+// just set/reset the flag telling it whether it should allow or forbid the
+// selection.
+//
+// Also notice that currently only a single object of this class may exist at
+// any given moment. It's just simpler like this and we don't need anything
+// more for now.
+
+extern "C"
+gboolean wxdataview_selection_func(GtkTreeSelection * WXUNUSED(selection),
+                                   GtkTreeModel * WXUNUSED(model),
+                                   GtkTreePath * WXUNUSED(path),
+                                   gboolean WXUNUSED(path_currently_selected),
+                                   gpointer data)
+{
+    return data == NULL;
+}
+
+class wxGtkTreeSelectionLock
+{
+public:
+    wxGtkTreeSelectionLock(GtkTreeSelection *selection)
+        : m_selection(selection)
+    {
+        wxASSERT_MSG( !ms_instance, "this class is not reentrant currently" );
+
+        ms_instance = this;
+
+        CheckCurrentSelectionFunc(NULL);
+
+        // Pass some non-NULL pointer as "data" for the callback, it doesn't
+        // matter what it is as long as it's non-NULL.
+        gtk_tree_selection_set_select_function(selection,
+                                               wxdataview_selection_func,
+                                               this,
+                                               NULL);
+    }
+
+    ~wxGtkTreeSelectionLock()
+    {
+        CheckCurrentSelectionFunc(wxdataview_selection_func);
+
+        gtk_tree_selection_set_select_function(m_selection,
+                                               wxdataview_selection_func,
+                                               NULL,
+                                               NULL);
+
+        ms_instance = NULL;
+    }
+
+private:
+    void CheckCurrentSelectionFunc(GtkTreeSelectionFunc func)
+    {
+        // We can only use gtk_tree_selection_get_select_function() with 2.14+
+        // so check for its availability both during compile- and run-time.
+#if GTK_CHECK_VERSION(2, 14, 0)
+        if ( gtk_check_version(2, 14, 0) != NULL )
+            return;
+
+        // If this assert is triggered, it means the code elsewhere has called
+        // gtk_tree_selection_set_select_function() but currently doing this
+        // breaks this class so the code here needs to be changed.
+        wxASSERT_MSG
+        (
+            gtk_tree_selection_get_select_function(m_selection) == func,
+            "selection function has changed unexpectedly, review this code!"
+        );
+#endif // GTK+ 2.14+
+
+        wxUnusedVar(func);
+    }
+
+    static wxGtkTreeSelectionLock *ms_instance;
+
+    GtkTreeSelection * const m_selection;
+
+    wxDECLARE_NO_COPY_CLASS(wxGtkTreeSelectionLock);
+};
+
+wxGtkTreeSelectionLock *wxGtkTreeSelectionLock::ms_instance = NULL;
+
 //-----------------------------------------------------------------------------
 // wxDataViewCtrlInternal
 //-----------------------------------------------------------------------------
@@ -4571,6 +4662,43 @@ bool wxDataViewCtrl::IsExpanded( const wxDataViewItem & item ) const
     return gtk_tree_view_row_expanded( GTK_TREE_VIEW(m_treeview), path );
 }
 
+wxDataViewItem wxDataViewCtrl::DoGetCurrentItem() const
+{
+    // The tree doesn't have any current item if it hadn't been created yet but
+    // it's arguably not an error to call this function in this case so just
+    // return an invalid item without asserting.
+    if ( !m_treeview )
+        return wxDataViewItem();
+
+    wxGtkTreePath path;
+    gtk_tree_view_get_cursor(GTK_TREE_VIEW(m_treeview), path.ByRef(), NULL);
+
+    return GTKPathToItem(path);
+}
+
+void wxDataViewCtrl::DoSetCurrentItem(const wxDataViewItem& item)
+{
+    wxCHECK_RET( m_treeview,
+                 "Current item can't be set before creating the control." );
+
+    // We need to make sure the model knows about this item or the path would
+    // be invalid and gtk_tree_view_set_cursor() would silently do nothing.
+    ExpandAncestors(item);
+
+    // We also need to preserve the existing selection from changing.
+    // Unfortunately the only way to do it seems to use our own selection
+    // function and forbid any selection changes during set cursor call.
+    wxGtkTreeSelectionLock
+        lock(gtk_tree_view_get_selection(GTK_TREE_VIEW(m_treeview)));
+
+    // Do move the cursor now.
+    GtkTreeIter iter;
+    iter.user_data = item.GetID();
+    wxGtkTreePath path(m_internal->get_path( &iter ));
+
+    gtk_tree_view_set_cursor(GTK_TREE_VIEW(m_treeview), path, NULL, FALSE);
+}
+
 wxDataViewItem wxDataViewCtrl::GetSelection() const
 {
     GtkTreeSelection *selection = gtk_tree_view_get_selection( GTK_TREE_VIEW(m_treeview) );