How to set the scroll position of a RichTextBox by behind code in WPF for every paragraph?

Question

I have a rich textbox and a long text with several paragraphs. I want to write behind codes to adjust the vertical position of the scroll bar to focus on a specific paragraph. Is it possible to calculate the vertical offset based on the size of the rich textbox and paragraph position?

RichTextBox.ScrollToVerticalOffset(calculatedData)

Answer 1

In order to obtain the position, initially, you should get the position of caret at the start of the paragraph. Then, you get the rectangle of bounding box. The Y property of the rectangle can scroll the paragraph at the first of the RichTextBox.

        private void RichTextBox_OnLoaded(object sender, RoutedEventArgs e)
        {
            // Get the paragraph block text
            var textBlock = RichTextBox.Document.Blocks.ElementAt(2);
            //get the caret position of the start of the paragraph
            var startOfTextBlock = textBlock.ContentStart;
            // get the the character rectangle
            Rect charRect = startOfTextBlock.GetCharacterRect(LogicalDirection.Forward);
            // set the the vertical offset ot the Y position of the rectangle 
            RichTextBox.ScrollToVerticalOffset(charRect.Y);
        }