AvalonEdit WPF TextEditor (SharpDevelop): How to highlight a specific range of text?

Question

The incredibly awesome AvalonEdit WPF TextEditor control seems to lack an important feature, or at least i can\'t figure it out. Given an offset and a length, highli

Answer 1

You need to create a custom ColorizingTransformer to do that. The above example is actually highlighting a specific word. Still, you can change it a little bit to to colorize or highlight a portion.

I used Avalon TextEditor for my Console+ project (which is in a very primitive stage at the moment)

public class OffsetColorizer : DocumentColorizingTransformer
{
    public int StartOffset { get; set; }
    public int EndOffset { get; set; }

    protected override void ColorizeLine(DocumentLine line)
    {
        if (line.Length == 0)
            return;

        if (line.Offset < StartOffset || line.Offset > EndOffset)
            return;

        int start = line.Offset > StartOffset ? line.Offset : StartOffset;
        int end = EndOffset > line.EndOffset ? line.EndOffset : EndOffset;

        ChangeLinePart(start, end, element => element.TextRunProperties.SetForegroundBrush(Brushes.Red));
    }
}

And you can add the colorizer to the editor by adding it to LineTransformers collection.

tbxConsole.TextArea.TextView.LineTransformers.Add(_offsetColorizer);