[PyQt] Problem with boundingRect in PyQt snapshot

[Phil Thompson]

On Thu, 17 Sep 2009 11:39:09 +0100, Mark Summerfield <list at qtrac.plus.com>
wrote:
> On 2009-09-16, Phil Thompson wrote:
>> On Wed, 16 Sep 2009 20:04:48 +0100, Jeremy Sanders
>> 
>> <jeremy at jeremysanders.net> wrote:
>> > Hi - for some reason the following code does not produce the
>> > correct answer after updating PyQt.
>> >
>> > On Ubuntu with the PyQt 4.4.4 package the following returns
>> > 18.0
>> >
>> > from PyQt4.QtGui import *
>> > from PyQt4.QtCore import *
>> > import sys
>> >
>> > app = QApplication(sys.argv)
>> >
>> > pix = QPixmap(128, 128)
>> > p = QPainter(pix)
>> > font = QFont("Times New Roman", 20)
>> >
>> > fm = QFontMetricsF(font, p.device())
>> > print fm.boundingRect(QChar('0')).height()
>> >
>> > On the same system with the same Qt (4.5.0), PyQt-x11-
>> > gpl-4.6-snapshot-20090906 and returns 32.0!
>> >
>> > The text is misaligned when using height to align it using
>> > the snapshot.
>> >
>> > My guess is that the QChar is being promoted to QString. This
>> > function returns a different result for QString, so it breaks
>> > my code. The QString version returns the font height, not the
>> > height of the character given.
>> 
>> Your guess is correct.
>> 
>> You could use tightBoundingRect() instead.
>> 
>> I can back out the automatic conversion from QChar to QString, but that
>> leaves the question of what should happen with v2 of the QString API,
ie.
>> should QChar not be dropped?
> 
> I think it would be a pity to keep it. Most of its methods are available
> in Python anyway, and for those few that aren't couldn't you provide
> some static methods that either take a one character string or that only
> consider the first character?

Do you want to go through the whole API and tell me the functions that
behave slightly differently given a QChar rather than a QString of length
one?

I don't have a problem with keeping it - it is a very specialised class and
you'd only use it if you really needed to.

Phil