[QScintilla] folding quirks

[Jared Sutton]

Hi All,

For the last several years (spare time) I've been constructing a simple
cross-platform code editor called QSciTE using Qt4 version of Qscintilla2.
 You can find it here, in case you're interested:

http://qscite.googlecode.com/

First off, thanks very much for making this library available to the public
under the GPL.  It has some wonderful functionality built-in.

I've been having some issues with code folding recently, which I believe to
have stemmed from at least one bug in Qscintilla.  I have a simple menu
option to enable/disable code folding.  Whenever I turn folding off, I want
any lines that are currently folded to be unfolded automatically, since it
doesn't make a whole lot of sense to have folded code that can't easily be
unfolded.  Here's my toggleFolding() function which is directly connected to
the menu option:

void MainWindow::toggleFolding() {
  QsciteEditor * doc = getCurDoc();
  QsciteEditor::FoldStyle state =
static_cast<QsciteEditor::FoldStyle>((!doc->folding()) * 5);

  if (!state) {
    // unfold all code before turning off folding
    doc->foldAll(false);
  }

  doc->setFolding(state);
}

The QsciteEditor class is a child-class of Qscintilla, because I needed to
expose several functions for use with QtScript, and because I needed to
catch some key-presses that I needed to process specially.  As you can see,
foldAll() is only getting called just before the folding is about to be
turned off.  The  documentation for foldAll() states "If any lines are
currently folded then they are all unfolded. Otherwise all lines are
folded."  Now, my implementation does not take into account the possibility
that no lines were folded between the time that the folding was enabled and
disabled (which I'll expand on below), meaning that if foldAll() works as
documented, I should expect to see all lines get folded before the folding
is disabled.  However, even when I fold one or more lines and then turn off
folding, I find that all lines are getting folded before folding gets
disabled.  This seems like it's a problem with the foldAll() implementation.

This also brings up a few questions:
1. Shouldn't setFolding() automatically unfold all lines that are currently
folded before the FoldStyle is set to NoFoldStyle?  Does anyone expect to
have lines folded after they disable folding?
2. If the person using QsciScintilla is expected to unfold all lines that
were folded before turning folding off, how can he know what lines are
folded?  As far as I can tell, that information is private, as are the
functions/signals/slots that are responsible for changing a line's fold
state.

So, I see these issues in the end:
1. There appears to be a bug in the QsciScintilla:foldAll(bool) function.
 It doesn't appear to function as documented.
2. In my opinion, QsciScintilla::setFolding() should either unfold
everything when folding is turned off, or the appropriate member
variables/functions/signals/slots should be changed from private to
protected so that developers can deal with the situation without resorting
to hacking on Qscintilla directly.

For what it's worth, here's my development environment:
Arch Linux
KDEmod 4.4.0
Qscintilla 2.4.2
Qt 4.6.1

Thanks for any insight you may have.

Jared Sutton
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.riverbankcomputing.com/pipermail/qscintilla/attachments/20100216/780f2c8f/attachment.html>