Goodbye wxWidgets, hello Qt!

I’ve been developing various pieces of software in wxWidgets (back when it was called wxWindows!) for a long time. But recently, I’ve made the switch to Qt.

WordTsar under wxWidgets was stable, and I used it to write quite a few novels (http://geraldbrandt.com), so why the switch? Well, it seems that I always had to do something just a little different based on what platform the software was running on. Don’t get me wrong, 99.9% of the code was cross platform and worked well, but there always seemed to be corner cases.

Qt version, Windows and Linux

The last straw for me was when I tried to get WordTsar running under MacOS. I tweaked here and there. Keyboard input was a pain, but then it was under Qt as well. It was just easier under Qt because I’d already fixed the issue under wxWidgets. So, what was it that I couldn’t get working?

wxTimers.

I use timers to update WordTsar’s status bar, do word counting, and flash the carat. None of it worked under MacOS. Again, I tweaked here and tweaked there, but I just couldn’t get timers to work. Really, timers are a pretty basic function. They should Just Work.

About two years back, I did a test port to Qt to help me find an elusive bug. I moved over just enough code to help track down the bug, and stopped. This time around, I didn’t.

QT Version – MacOS

WordTsar is now 100% Qt based, with all the functionality of version 0.1 Release 1977. Well, almost. The Linux version of WordTsar had spell check working, using Hunspell. Non of the other ports did. I’ve decided to leave spell check out since I want to do it in a more cross-platform way.

What differences will you see with the Qt port? Some of the dialogs look different. Yup, that’s pretty much it.

Well, except for one thing.

Speed.

The Qt version is SIGNIFICANTLY faster than the wxWidgets version. Why? Two things in particular:

  1. Measuring of text under Qt just flies. Under Linux, measuring the widths of 605,814 characters took roughly 1800 ms. With the code optimized to measure strings instead of characters, I got that down to 460 ms. Under Qt, which can only measure individual character widths* the speed is 138 ms. That is a massive speed improvement.
  2. QString vs wxString is the second big increase. I do a lot of parsing of strings using .Mid(), .BeforeFirst(), .Left(), etc. I do no in string indexing (i.e. string[x]). Parsing WordTsar dot commands (string heavy) on a 111,000 word novel took 1060 ms under wxWidgets. With Qt, that process took 348 ms. I was planning to optimize the dot command routines to speed things up, and I still will (via some form of caching), but I can postpone that work now.

What this all comes out to, is under wxWidgets, laying out a 111,000 word document took 1670 ms. Not bad, really. Under Qt, the same process takes 576 ms. That’s a very noticeable difference.

I’ll be testing the Qt version over the next week by editing a 92,000 word novel and bringing that up to 100,000 words or so. Not a bad stress test. If all works out, there will be a WordTsar 0.2 Release xxxx happening next week for Linux, Windows, and MacOS.

* wxWidgets has GetPartialTextExtents() which, when passed in a string, will return an array of character widths. Qt has no such function. You can get the width of an entire string, but not the characters in that string. So, with Qt, I must measure each character.

If you enjoyed this post, please consider leaving a comment or subscribing to the RSS feed to have future articles delivered to your feed reader.
Bookmark the permalink.

Leave a Reply

Your email address will not be published.

*