widget not visible after layout->setAlignment

The follow code shows the first widget added, (playerControlsToolbar, essentially a QToolBar) but not the TimeSlider widget (a custom widget with its own layout, a slider bar and a couple of labels as children).

If I comment out the 5th line, it does show up. (The same things happens if I add the TimeSlider using addWidget( pb, 0, Qt::AlignCenter) ).

Code:

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QVBoxLayout *playerAndSliderLayout = new QVBoxLayout;
playerAndSliderLayout->addWidget( playerControlsToolbar, 0, Qt::AlignCenter );
TimeSlider* pb = new TimeSlider( m_controlBar );
playerAndSliderLayout->addWidget( pb );
playerAndSliderLayout->setAlignment( pb, Qt::AlignCenter );

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The layout does leave space for the "ghost" widget, it just doesn't show it.

When do you invoke the above code snippet? Have you tried creating TimeSlider without a parent?

When setting up a window. And yes I have tried it with a 0 parent.

Quote:

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Originally Posted by eean

When setting up a window.

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So the window isn't visible yet, right?

What do you do with playerAndSliderLayout later?

Quote:

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Originally Posted by jacek

So the window isn't visible yet, right?

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Well its in an init() function (not the constructor) so I'd assume its technically already visible.

Quote:

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Originally Posted by jacek

What do you do with playerAndSliderLayout later?

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Nothing, it goes out of scope. Well, I set it as the layout for m_controlBar.

I actually redid the whole thing using Designer. Apparently designer doesn't let you set what the layout alignments are? So I did the following:

Code:

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m_controlBar = new QWidget( this );
m_controlBar->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Minimum );
Ui::ControlBar uicb;
uicb.setupUi( m_controlBar );
 
#define center( A, O ) uicb.A##boxLayout->setAlignment( uicb.O, Qt::AlignCenter )
center( v, m_progressBar );
center( v, m_playerControlsToolbar );
center( h, m_searchWidget );
center( h, m_analyzerWidget );
center( h, m_volumeWidget );
#undef center

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Which compiles and I think does what its supposed to do.

...but everything but the m_playerControlsToolbar is invisible, just like before!

Quote:

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Originally Posted by eean

Well its in an init() function (not the constructor) so I'd assume its technically already visible.

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If it's already visible, then you have to invoke pb->show() yourself.

Quote:

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Originally Posted by eean

...but everything but the m_playerControlsToolbar is invisible, just like before!

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Have you placed m_controlBar inside some layout?

Quote:

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Originally Posted by jacek

If it's already visible, then you have to invoke pb->show() yourself.

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Just tried that (added uicb.O->show() to the center macro above) and it has no effect. I don't see how this would be the issue since one widget is shown correctly.

Quote:

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Originally Posted by jacek

Have you placed m_controlBar inside some layout?

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Its inserted into a splitter which is parented to the main window. So no, not really.

zchydem from #qt actually wrote a test program:
http://qtnode.net/pastebin/2554
And he says it all works correctly. :confused:

attached is an svn diff from Amarok 2.0, in case anyone has a KDE4 development environment laying around. ;)

Quote:

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Originally Posted by eean

Just tried that (added uicb.O->show() to the center macro above) and it has no effect. I don't see how this would be the issue since one widget is shown correctly.

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Then maybe there is some problem with that custom widget?

Try something like this:

Code:

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int main( int argc, char **argv )
{
  QApplication app( argc, argv );
 
  TimeSlider w;
  w.show();
 
  return app.exec();
}

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to check whether this TimeSlider behaves correctly.

Quote:

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Originally Posted by eean

Its inserted into a splitter which is parented to the main window. So no, not really.

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But splitters behave like layouts, so it should be OK.

Another Amarok dev (Dan) tried to do this, but then realized that TimeSlider requires a bunch of other files to work.

Anyways, TimeSlider (and the other widgets with the same problem) did work as part of a grid layout previously. And of course, they work without their alignment set. :)

Quote:

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Originally Posted by eean

And of course, they work without their alignment set.

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That's weird. Unfortunately I don't have KDE4 at hand, so I can't play with Amarok's code.