[Android-development] Android Style (widget-based)

[maitai at virtual-winds.org]

Hello all,

Following another conversation on this list, I have started modifying 
qandroidstyle in order to fix or improve a few things.

Good news: I have implemented checkable groupboxes, and I also fixed 
that annoying problem with spinboxes size. (QTBUG-37965 and QTBUG-38325)

I am now turning my attention on QTBUG-38717. The problem is with 
QTableView headers size being wrong. What I discovered is that the 
problem is not actually coming from androidStyle, but exists also with 
QCommonStyle. It occurs only if a general styleSheet has been applied at 
QApplication level, even if the styleSheet is not related to Headers.

For instance I have in my mainwindow constructor:

         QString styleA="QToolBox::tab:unselected{color:black;"
                 "background-color:qlineargradient(x1: 0, y1: 0, x2: 1, 
y2: 0,"
                 "stop: 1 #fffb90, stop: 0 #ffd800);}"
                 "QToolBox::tab:selected{color:white;"
                 "background-color:qlineargradient(x1: 0, y1: 0, x2: 1, 
y2: 0,"
                 "stop: 1 #00a2ff, stop: 0 #2307ae);}";
         qApp->setStyleSheet(styleA);

If I do that it changes somehow the font of tableViews, the font for 
items is unchanged, but the font for headers becomes the default 
application font, which is bigger. If I don't apply the stylesheet then 
QTableView headers font is not changed, and all is fine. Note that this 
strange change of tableView header's font occurs only on Android, on 
Windows if I apply the styleSheet the header remain the same. That is 
the first problem.

The second probem is that QCommonStyle does not catch the font for 
headers. In QCommonStyle.cpp line 4782:

              QSize txt = hdr->fontMetrics.size(0, hdr->text);

does not report the correct size, but the size as if the styleSheet was 
not applied.

To fix it I reimplemented sizeFromContents in qandroidstyle for 
CT_HeaderSection and replaced above line with

             QSize txt;
             if(qApp->styleSheet().isEmpty())
                 txt = hdr->fontMetrics.size(0, hdr->text);
             else
                 txt = qApp->fontMetrics().size(0, hdr->text);

But of course this is a very bad hack...

So there are 2 questions:

Why applying a styleSheet at application level changes the font of 
QTableView headers even if no header section is specified in the string?

How can I catch the actual font of header in a QStyle-derived class?

Thanks for any clue to improve on that one, it could also be that I 
missed something...

Philippe LELONG