LogViewer

LogViewer is a WPF control which displays logging information in a RichTextBox, scrolling always to the end of the content. LogViewer can also display temporary content, which gets overwritten as soon permanent content gets written. Use Case: A program has to process all files of a directory. In the end, only some directory statistics needs to get displayed to the user, but during the processing, LogViewer should display the name of each file currently processed. If several files get processed within 100 milliseconds, only 1 name gets actually written to the LogViewer. It would not make sense to update LogViewer every few milliseconds, WPF would be too slow to perform so many updates and the user could anyway not see them. Instead LogViewer collects all information, but passes it on only every 100 milliseconds to the WPF thread. If there is now a file that needs seconds for processing, the user can actually see which file takes that long.

The Write methods for LogViewer are multithreading safe. To keep WPF responsive, one often has to do processing on a different threat. The code of this thread does not need to know how to write bold or use different fonts. Instead, the class StyledString defines certain styles and the code activates them like this:

logViewer.WriteTempLine("some content temporarily displayed to user");
logViewer.WriteLine("This is a Title", StringStyleEnum.header1);
LogViwere.WriteLine("Some text without formatting.");

It is recommended to just copy the 2 files LogViewer.cs and StyledString.cs into your application and then change according to your needs. Add the different formatting you need to StringStyleEnum in StyledString.cs:

public enum StringStyleEnum {
  none = 0,
  normal,
  label,
  header1,
  errorHeader,
  errorText,
}

You also need to update the switch statement in the method `StyledString.ToInline(Paragraph styledParagraph, string

lineString, StyledString styledString)`. You need to add one case for every value you added to StringStyleEnum:

case StringStyleEnum.errorHeader:
  styledParagraph.Margin = new Thickness(0, 24, 0, 4);
  inline = new Bold(new Run(lineString));
  inline.FontSize = styledParagraph.FontSize * 1.2;
  inline.Foreground = Brushes.Red;
  break;

For design details and more details see my article on CodeProject: https://www.codeproject.com/Articles/5340961/LogViewer-A-fast-WPF-Control-displaying-logging-in