c# - Saving RichTextBox FlowDocument to image

Question

i'am making a programm where i want my RichTextBox content (text+images) to be saved as an image (jpg/png). I tried to use this solution but i get only black filled image from

SaveUIAsGraphicFile() 

I also tried to create FormattedText from my rtb control, printing it works fine, but its not possible to insert images in there. Maybe it is possible to print FlowDocument somehow?

Answer 1

You could use something like the following method to create a bitmap from a FlowDocument:

public BitmapSource FlowDocumentToBitmap(FlowDocument document, Size size)
{
    document = CloneDocument(document);

    var paginator = ((IDocumentPaginatorSource)document).DocumentPaginator;
    paginator.PageSize = size;

    var visual = new DrawingVisual();
    using (var drawingContext = visual.RenderOpen())
    {
        // draw white background
        drawingContext.DrawRectangle(Brushes.White, null, new Rect(size));
    }
    visual.Children.Add(paginator.GetPage(0).Visual);

    var bitmap = new RenderTargetBitmap((int)size.Width, (int)size.Height,
                                        96, 96, PixelFormats.Pbgra32);
    bitmap.Render(visual);
    return bitmap;
}

public FlowDocument CloneDocument(FlowDocument document)
{
    var copy = new FlowDocument();
    var sourceRange = new TextRange(document.ContentStart, document.ContentEnd);
    var targetRange = new TextRange(copy.ContentStart, copy.ContentEnd);

    using (var stream = new MemoryStream())
    {
        sourceRange.Save(stream, DataFormats.XamlPackage);
        targetRange.Load(stream, DataFormats.XamlPackage);
    }

    return copy;
}

and then use it like shown below to save a RichTextBox's Document to an image file.

var doc = richTextBox.Document;
var bm = FlowDocumentToBitmap(doc, new Size(richTextBox.ActualWidth, richTextBox.ActualHeight));
var encoder = new JpegBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bm));

using (var stream = new FileStream("doc.jpg", FileMode.Create))
{
    encoder.Save(stream);
}