string[] messageSplit = message.Split(' ');
FlowDocument doc = new FlowDocument();
Paragraph paragraph = new Paragraph();

for (int i = 0; i < messageSplit.Length; ++i) {
            string str = messageSplit[i];
            if (str.Contains("${emoteId=")) {

                string id = ...
                Image image = new Image();
                image.Source = (ImageSource)((new ImageSourceConverter()).ConvertFromString($@"emotes/{id}.png"));

                BlockUIContainer cont = new BlockUIContainer(image);
                Figure figure = new Figure(cont);
                figure.Width = (new FigureLength(24));
                figure.WrapDirection = WrapDirection.Both;
                figure.VerticalAnchor = FigureVerticalAnchor.PageTop;
                figure.HorizontalAnchor = FigureHorizontalAnchor.PageLeft;

                paragraph.Inlines.Add(figure);
            } else {
                paragraph.Inlines.Add(new Run(str));
            }
        doc.Blocks.Add(paragraph);
        MessageText.Document = doc;