[Qt-interest] Calculating text size in QLineEdit

[Matthias Paul]

-------- Original-Nachricht --------
> Datum: Tue, 8 Mar 2011 21:30:02 +1100
> Von: "Tony Rietwyk" <tony.rietwyk at rightsoft.com.au>
> An: qt-interest at trolltech.com
> Betreff: Re: [Qt-interest] Calculating text size in QLineEdit

> > Sent: Tuesday, 8 March 2011 21:11
> > -------- Original-Nachricht --------
> > > Datum: Tue, 8 Mar 2011 10:20:23 +0100
> > > Von: "Andre Somers" <andre at familiesomers.nl>
> > > An: "\'qt-interest at trolltech.com\'" <qt-interest at trolltech.com>
> > > Betreff: Re: [Qt-interest] Calculating text size in QLineEdit
> > 
> > > Op Di, 8 maart, 2011 10:06 am, schreef Matthias Paul:
> > > > Hello!
> > > >
> > > > I created a QLineEdit subclass, which automatically 
> > displays a truncated
> > > > text if the original text is too long for the widget's 
> > size, so that
> > > > there's no need to scroll for the user. Instead a tooltip 
> > with full text
> > > > is displayed.
> > > >
> > > > QFontMetrics calculates the size required for the 
> > displayed text based
> > > on
> > > > QWidget's size() (provided by ResizeEvent). Still, I 
> > cannot figure out
> > > how
> > > > to get the the text label size _minus_ widget's borders 
> > and margins.
> > > Guess
> > > > I have to use QStyle somehow, so can someone give me a 
> > hint please?
> > > 
> > > Perhaps you can use QStyle::subElementRect, using
> > > QStyle::SE_LineEditContents for the element argument, and a 
> > style option
> > > initialized with your line edit widget as the style option? 
> > That should
> > > give you the rect that is available to draw the text.
> > > 
> > > André
> > > 
> > 
> > Hello André!
> > 
> > Thank you for your reply!
> > 
> > The subelementRect() always returns an invalid QRect, 
> > although the QLineEdit is displayed and has content in it.
> > 
> > That's what I tried: (typos included)
> > --------------------------------------------------
> > void
> > TruncatedLineEdit::resizeEvent(
> >     QResizeEvent * resizeEvent) {
> > 
> >   QLineEdit::resizeEvent(resizeEvent);
> > 
> >   qDebug() << "QWidget's size (by event):" << resizeEvent->size();
> >   QStyleOption option;
> >   option.initFrom(this);
> >   qDebug() << "QWidget's content rect (by style):"
> >            << this->style()->subElementRect(
> >                   QStyle::SE_LineEditContents,
> >                   &option,
> >                   this);
> >   // do smth with size information
> > }
> > --------------------------------------------------
> > 
> > The output is:
> > --------------------------------------------------
> > QWidget's size (by event): QSize(246, 22)
> > QWidget's content rect (by style): QRect(0,0 0x0)
> > --------------------------------------------------
> > 
> > 
> > Is it because QLineEdit has no user-style set to it? 
> > QLineEdit has been set with usual calls like setFont(), 
> > setReadOnly() and setObjectName().
> > -- 
> 
> Hi Matthias, 
> 
> Does QWidget.contentsRect() work for you? 
> 
> Tony

Hello Tony!

QWidget.contentsRect() returns the same as size().
I tried getContentsMargins() too, but this seems to return the outer margins, not the margins between QLineEdit's border and content.

As a workaround I set a fixed value for margin/border, but that isn't portable to other systems/styles. I may not even work for other font sizes.

> 
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