evoleap/AvalonEdit

This is a fork of AvalonEdit.

1. Modifications:

• Added "Hiding" feature
  • It enables hiding of lines or group of lines
  • It shares some logic with "Folding" feature, but with some important differences/notes:
    • Hiding is used as a one-time application (can be toggled on or off), and not periodically checked like folding
    • Hiding sections should not overlap with each other or with folding sections
    • With folding sections, the first line is never collapsed and there is a corresponding visual line - with hiding this is not the case. This has several consequences:
      • Multiple places in code need to be adjusted to overcome that limit
      • It can cause the whole document to be hidden - we need to disable the editor in such case
      • Text removal - multiple actions can lead to text removal and some of them lead to Editing\EditingCommandHandler.cs -> static ExecutedRoutedEventHandler OnDelete(CaretMovementType caretMovement) method
        • Current logic for text removal is based on old and new visual positions of the caret, which is fine for folding but not for hiding.
  • Progress:
    • Currently, when we switch to filtered view (where some lines are hidden) we make it read-only, since there are some noticed bugs with text removal (adding lines or modifying parts of lines seems fine - what is tested so far)
    • To enable editing, we need to:
      • Probably differentiate between folding and hiding CollapsedLineSection - partially implemented (see also HeightTree - it does not directly hold CollapsedLineSections).
      • Adjust text removal logic (and potentially some other places) to accommodate this:
        • Removal without selection
        • Removal with selection
          • Here we also need to split removal into multiple removals in some cases
        • ...
• Added the UseLongestLineWidthAsScrollableWidth option
  • This option allows the longest line width to be used as the scrollable width, similar to behavior seen in VS Code and several other editors.
  • Example:

    •   textEditor.Options.UseLongestLineWidthAsScrollableWidth = true;
        ...
        textView.ShouldUpdateLongestLineWidth = true;
        textView.InvalidateMeasure();
        Dispatcher.CurrentDispatcher.BeginInvoke(DispatcherPriority.Background, new System.Action(() =>
        {
            textView.ShouldUpdateLongestLineWidth = false;
        }));