Best way to work with ITextChange?

Hi Simon,

A text change is what applies text replace operations to move from one snapshot to a new one.  Think of the snapshot text as a long string.  When you first start a text change, the snapshot text is retrieved and the first operation works directly on that original text.  Now you end up with a variable of the revised text.  All offsets now need to be relative to what is currently in that variable.  There are several ways to do this.

1) Do your operations in reverse order.  Meaning since the second replace starts later in the chain than the first, execute it first then do the first operation last.  This requires minimal tracking but only works if you have non-overalpping text change operations.

2) We have a built-in feature that can track and apply offset deltas so that you don't have to think about them.  In your case, this would work.  Create your text change like:

options.OffsetDelta = TextChangeOffsetDelta.SequentialOnly;
ITextChange textChange = snapshot.CreateTextChange(TextChangeTypes.Indent, options);

Then run the same lines you had before.  It will be tracking that the first operation had a net offset delta of 1 and will then change the start offset of your second call automatically to 4 (your specified 3 + delta 1).  This option only works if the operations are always in sequential order.  Please see the documentation for that offset delta option.  We use that for things like Indent, etc.

3) Track the character delta yourself.  You can always fall back to this but it's more work than either of the two cases above.  However you can use it in scenarios when the other two don't work.

Overall I would recommend using options 1 or 2 whenever possible.