[Qt-interest] keyPressEvent() confusion with dead keys/accents correctly

[Atlant Schmidt]

Nikos:

  Are you sure you're looking at the key data from the
  Key event and not KeyPress or KeyRelease events? Those
  "enclosing" events are likely to be raw keys whereas
  the Key event will likely contain the final "cooked"
  keycode.

  (But it's been a few months since I last dealt with
  this so my memory may be faulty.)

                          Atlant


-----Original Message-----
From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Nikos Chantziaras
Sent: Wednesday, September 29, 2010 13:01
To: qt-interest at trolltech.com
Subject: [Qt-interest] keyPressEvent() confusion with dead keys/accents correctly

Basically, I ran across this exact same problem:

http://www.qtcentre.org/threads/4653-Handling-of-dead-keys-in-keyPressEvent%28%29

   I want to capture key presses, including dead keys.
   So for instance, if you press ~ and afterwards n,
   you get ñ (at least on a Spanish keyboard layout).

   When I reimplement keyPressEvent() in my widget, I
   get however always the ~ and n separately. I would
   rather get only one keyPressEvent() with the
   complete character.

On his system it was a keyboard layout problem.  However, I don't have
keyboard layout problems and other Qt applications work correctly in
this regard (I can input accents correctly in Creator for example, or
any demo app that comes with Qt, or any other Qt app I have installed on
my system, including the whole of KDE.)  So it seems I'm doing it wrong
in my keyPressEvent()?

My keyPressEvent() receives dead keys.  AFAIK, it shouldn't receive them
in the first place, because when compiling the application for Windows,
it doesn't.  It does only on Linux.  Furthermore, if I ignore dead keys
with something like:

   if (e->key() >= Qt::Key_Dead_Grave && e->key() <= Qt::Key_Dead_Horn) {
       QScrollArea::keyPressEvent(e);
       return;
   }

then I get rid of the problem of printing dead keys, but the next key
event I get still does not contain the correct, accented character in
its e->text().  It contains the unaccented one.

Turning on key compression with setAttribute(Qt::WA_KeyCompression) does
not help.

Studying the source code of QTextEdit and its keyPressEvent()
implementation didn't turn up anything useful either.

My keyPressEvent() implementation can be simplified to this:

   if (e->text().isEmpty() || !e->text().at(0).isPrint()
       || (e->key() >= Qt::Key_Dead_Grave
           && e->key() <= Qt::Key_Dead_Horn))
   {
       QScrollArea::keyPressEvent(e);
       return;
   }

   qDebug() << e->text()

In this implementation, qDebug will *never* print a "ñ".  It's always
just "n".
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