CODEWITHSUNDEEP
c#windows
user2478625
user2478625

Reputation: 133

"Out of Memory" while populating TreeView

I am facing "Out of Memory" issue when I am populating TreeView hierarchy using XML. Our XML structure is very complex and it is not in fix format. There are multiple level of child nodes. I am using recursion to iterate XML and populate TreeView structure. I tried to call GC.Collect. to clear memory but still it is throwing same error. I am using C# of .NET framework 3.5 for development.

I will appreciate if you can help me to find solution for this.

I'm providing the Code, Which I'm using for populating the treeview, below

private void addTreeNode(XmlNode xmlNode, TreeNode treeNode)
{
    string attribute = "";

    treeView1.ImageList = imageList1;
    treeViewResponse.ImageList = imageList1;
    XmlNode xNode;
    TreeNode tNode;
    XmlNodeList xNodeList;
    foo.MoveToFollowing(XPathNodeType.Element);
    namespaces1 = foo.GetNamespacesInScope(XmlNamespaceScope.All);
    if (xmlNode.HasChildNodes)
    {

        treeNode.ImageIndex = 0;
        treeNode.SelectedImageIndex = 0;
        xNodeList = xmlNode.ChildNodes;
        for (int x = 0; x <= xNodeList.Count - 1; x++)
        {
            xNode = xmlNode.ChildNodes[x];
            treeNode.Nodes.Add(new TreeNode(xNode.Name));
            tNode = treeNode.Nodes[x];
            //treeNode.Nodes[x].ImageIndex = -1;
            addTreeNode(xNode, tNode);
        }
    }
    else
    {
        treeNode.ImageIndex = 1;
        treeNode.NodeFont = new Font("Arial", 8, FontStyle.Bold);
        treeNode.SelectedImageIndex = 1;
        treeNode.Text = xmlNode.OuterXml.Trim();
    }
}

Upvotes: 3

Views: 2539

Answers (1)

Steven Knauber
Steven Knauber

Reputation: 51

As Raymond suggested, you should construct the font one time and reuse it. I have noticed that even if you do this, changing node fonts immediately causes a redraw of the control which can cause TreeView to construct internal fonts in addition to the one you provided it. I have seen cases where this can cause the font handle usage to go up very fast such that the garbage collector does not free them fast enough. I think this is a bug in TreeView that is not very repeatable but will happen sometimes. A way to protect yourself against Treeview using all your application's GDI handles is to wrap a set of node adds or font changes in TreeView.BeginUpdate() and TreeView.EndUpdate() calls.

m_treeView.BeginUpdate();
try
{
    // TreeNode adds changes here
}
finally
{
    m_treeView.EndUpdate();
}

This will result in only one redraw even though you added or changed multiple nodes.

Steve

Upvotes: 5

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