Asking for recommendations on how to add a feature to KTextEditor

[Michal Srb]

Hi,

I would like to ask for hints/recommendations on how to implement a
feature for KTextEditor.

My ultimate goal is to make a plugin for KDevelop that will show some
additional information in the code itself. For example names of
function arguments at call site. Something like this in intellij:
https://d3nmt5vlzunoa1.cloudfront.net/idea/files/2016/09/Screen-Shot-2016-09-27-at-10.29.15.png

For this I would need a way to render something in the text, affecting
the layout of the line. It would be nice to be able to place any
general widget or image into the line, but even plain text would be
sufficient. It must behave differently than the "real" text around it,
such that it can not be edited, cursor skips it, copying does not copy
it, etc.

So far I thought of adding something like `AnnotationViewInterface`,
which would allow to add this kind of immutable text on line+column
position. Then in `KateRenderer` it could take these into
consideration when layouting the line and render it in. It would be
visible in the text, but never become a real part of the text.

Would you recommend some other approach, or is there perhaps a way to
do it without modifying KTextEditor?

Thank you,
Michal Srb