Export Gantt Grid as Image

public void ExporGridtBtn_Click(object sender, System.Windows.RoutedEventArgs e)
        {
            RenderTargetBitmap bmp;
            BitmapEncoder bitmapEncoder;
            int width;
 
            GanttControl Gantt = this.AssociatedObject.TabControl.SelectedContent as GanttControl;
 
            GanttGrid tmp = Gantt.FindName<GanttGrid>("PART_GanttGrid");
            ScrollViewer chartGrid = tmp.FindName<ScrollViewer>("PART_ScrollViewer");
 
            Gantt.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
            Gantt.Arrange(new Rect(new Size(Gantt.DesiredSize.Width, Gantt.DesiredSize.Height)));
            bmp = new RenderTargetBitmap(
               (int)Gantt.DesiredSize.Width, (int)Gantt.DesiredSize.Height, 96, 96, PixelFormats.Default);
 
            bmp.Render(chartGrid);
 
            width = (int)(Gantt.DesiredSize.Width - chartGrid.ActualWidth);
 
            CroppedBitmap crpBmp = new CroppedBitmap(bmp, new Int32Rect(0, 0, width, (int)Gantt.DesiredSize.Height));
 
 
            bitmapEncoder = new PngBitmapEncoder();
            bitmapEncoder.Frames.Add(BitmapFrame.Create(crpBmp));
 
            SaveFileDialog saveFileDialog = new SaveFileDialog();
 
            saveFileDialog.FileName = "Untitled";
            saveFileDialog.DefaultExt = "png";
            saveFileDialog.Filter = "PNG Files (*.png)|*.png|Jpeg Files (*.jpg)|*.jpg|Bitmap Files (*.bmp)|*.bmp|All files (*.*)|*.*";
            saveFileDialog.FilterIndex = 1;
 
            if (saveFileDialog.ShowDialog() == true)
            {
                using (Stream stream = saveFileDialog.OpenFile())
                {
                    bitmapEncoder.Save(stream);
                    stream.Close();
                    System.Diagnostics.Process.Start(saveFileDialog.FileName);
                }
            }
        }