Using QT to build a WYSIWYG Editor for a Custom Markup Language

Posted by Aaron on Stack Overflow See other posts from Stack Overflow or by Aaron
Published on 2010-03-09T05:28:19Z Indexed on 2010/03/09 5:36 UTC
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I'm new to QT, and am trying to figure out the best means of creating a WYSIWYG editor widget for a custom markup language that displays simple text, images, and links. I need to be able to propagate changes from the WYSIWYG editor to the custom markup representation.

As a concrete example of the problem domain, imagine that the custom markup might have a "player" tag which contains a player name and a team name. The markup could look like this:

Last week, <player id="1234"><name>Aaron Rodgers</name><team>Packers</team></player> threw a pass.
This text would display in the editor as:

Last week, Aaron Rodgers of the Packers threw a pass.

The player name and the team name would be editable directly within the editor in standard WYSIWYG fashion, so that my users do not have to learn any markup. Also, when the player name is moused-over, a details pop-up will appear about that player, and similarly for the team.

With that long introduction, I'm trying to figure out where to start with QT. It seems that the most logical option would be the Rich Text API using a QTextDocument. This approach seems less than ideal given the limitations of a QTextDocument:

  • I can't figure out how to capture navigation events from clicking on links.
  • Following links on click seems to only be enabled when the QTextEdit is readonly.
  • Custom objects that implement QTextObjectInterface are ignored in copy-and-paste operations
  • Any HTML-based markup that is passed to it as Rich Text is retranslated into a series of span tags and lots of other junk, making it extremely difficult to propagate changes from the editor back to the original custom markup.

A second option appears to be QWebKit, which allows for live editing of HTML5 markup, so I could specify a two-way translation between the custom markup and HTML5. I'm not clear on how one would propagate changes from the editor back to the original markup in real-time without re-translating the entire document on every text change. The QWebKit solutions looks like awfully bulky to me (Learning WebKit along with QT) to what should be a relatively simple problem.

I have also considered implementing the WYSIWYG with a custom class using native QT containers, labels, images, and other widgets manually. This seems like the most flexible approach, and the one most likely not to run into unresolvable problems. However, I'm pretty sure that implementing all the details of a normal text editor (selecting text, font changes, cut-and-paste support, undo/redo, dragging of objects, cursor placement, etc.) will be incredibly time consuming.

So, finally, my question: are there any QT gurus out there with some advice on where to start with this sort of project?

BTW, I am using QT because the application is a desktop application that needs platform independence.

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