Question

I want to implement something that programmatically changes the background of the text when provided with a documentline.(Something that looks very similar to a block selection of a text. I’m going to be using this for debug breakpoints of an IDE I’m designing). I don’t want to have to use selection as it causes the textbox to scroll.

I think I need to make use of DocumentColorizingTransformer but I’m not 100% sure how to go about this.

public class ColorizeAvalonEdit : ICSharpCode.AvalonEdit.Rendering.DocumentColorizingTransformer
    {
        protected override void ColorizeLine(ICSharpCode.AvalonEdit.Document.DocumentLine line)
        {
            int lineStartOffset = line.Offset;
            string text = CurrentContext.Document.GetText(line);
            int start = 0;
            int index;
            if (line.LineNumber == LogicSimViewCodeWPFCtrl.currentLine)
            {
                while ((index = text.IndexOf(text, start)) >= 0)
                {
                    base.ChangeLinePart(
                        lineStartOffset + index, // startOffset
                        lineStartOffset + index + text.Length, // endOffset
                        (VisualLineElement element) =>
                        {
                            element.TextRunProperties.SetBackgroundBrush(Brushes.Red);

                        });
                    start = index + 1; // search for next occurrence
                }
            }
        }
    }

currentLine is the portion that will be highlighted.

The above code does work properly.. only problem is if the currentLine ever changes while I am viewing that line, it doesn’t highlight the updated line until I scroll to another portion of the document (hiding the updated line), and come back to the updated line.

Also, how do I make the line numbers start from zero?

Answer 1

I found the answer

TxtEditCodeViewer.TextArea.TextView.Redraw();