WPF

private readonly XNamespace _xamlNS  = @"http://schemas.microsoft.com/winfx/2006/xaml/presentation";
private readonly XNamespace _sysNS   = @"clr-namespace:System;assembly=mscorlib";
private readonly XNamespace _xNS     = @"http://schemas.microsoft.com/winfx/2006/xaml";
private readonly XNamespace _localNS = @"clr-namespace:System;assembly=WpfConsoleApp";

//--------------------------------------------------------------------------------
public void ImagesFromText2(string folder)
{
    foreach (DynamicContentItem item in ContentItems)
    {
        if (item.ContentType == "text")
        {
            XElement container = new XElement("Canvas",
                            new XAttribute("xmlns", _xamlNS),
                            new XAttribute("xmlns:x", _xNS),
                            new XAttribute("xmlns:local", _localNS),
                            new XAttribute("Padding", "0,0,0,0"),
                            new XAttribute("Width", item.CanvasElement.Width.ToString()),
                            new XAttribute("Height", item.CanvasElement.Height.ToString()));

            XElement child = item.CanvasElement.AsXElement;
            string xaml = child.ToString();

            child.Name = @"{http://clearchannel.com/spotchart/WpfConsoleApp}SpotChartTextBlock";
            //xElement.RemoveAttribute("Background");
            //xElement.RemoveAttribute("Panel.ZIndex");
            //xElement.RemoveAttribute("Canvas.Right");
            //xElement.RemoveAttribute("Canvas.Bottom");
            //xElement.RemoveAttribute("Canvas.Left");
            //xElement.RemoveAttribute("Canvas.Top");
            child.SetAttributeValue("Margin", "0,0,0,0");
            child.SetAttributeValue("xmlns", _xamlNS);
            child.SetAttributeValue("xmlns:x", _xNS);
            child.SetAttributeValue("xmlns:local", _localNS);

            string text = item.LocalData;
            if (item.CanvasElement.IsDateTime)
            {
                child.SetAttributeValue("Text", item.LocalDataFormatted);
            }
            child.Name = @"{http://clearchannel.com/spotchart/WpfConsoleApp}SpotChartTextBlock.RenderTransform";
            container.Add(child);

            xaml = container.ToString();
            Canvas canvas = (Canvas)(XamlReader.Parse(xaml));

            SpotChartTextBlock textBlock    = (SpotChartTextBlock)(canvas.Children[0]);
            textBlock.VerticalTextAlignment = item.VerticalAlign;
            textBlock.SizeToFit             = item.SizeToFit;
            textBlock.MinimumFontSize       = item.MinimumFontSize;
            textBlock.Process();
            int width = (int)textBlock.Width;
            int height = (int)textBlock.Height;

            RenderTargetBitmap rtb = new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Pbgra32);
            DrawingVisual dv = new DrawingVisual();
            using (DrawingContext ctx = dv.RenderOpen())
            {
                VisualBrush vb = new VisualBrush(canvas);
                ctx.DrawRectangle(vb, null, new Rect(new Point(), new Size(width, height)));
            }
            rtb.Render(dv);
            PngBitmapEncoder png = new PngBitmapEncoder();
            png.Frames.Add(BitmapFrame.Create(rtb));
            MemoryStream stream = new MemoryStream();
            png.Save(stream);
            System.Drawing.Image image = System.Drawing.Image.FromStream(stream);
            image.Save(System.IO.Path.Combine(folder, string.Format("{0}.png", item.ElementName)));
        }
    }
}

public new string Text
{
    get { return (string)GetValue(TextProperty); }
    set { SetValue(TextProperty, value); }
}

public new static readonly DependencyProperty TextProperty =
    DependencyProperty.Register("Text", typeof(string),
    typeof(HighlightTextBlock), new FrameworkPropertyMetadata(string.Empty, FrameworkPropertyMetadataOptions.AffectsRender,
        new PropertyChangedCallback(UpdateHighlighting)));

private static void UpdateHighlighting(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    ApplyHighlight(d as HighlightTextBlock);
}