QScrollArea inner widget problem

[agaf]

I need QScrollArea to contains some images

TestScrollArea::TestScrollArea(QWidget *parent, Qt::WFlags flags)
	: QMainWindow(parent, flags)
{
	ui.setupUi(this);
 
	QWidget* widget = new QWidget;
	QVBoxLayout* layout = new QVBoxLayout( widget);
 
	QImage image("D:\\data\\photo\\me\\bg2009.jpg");
	Q_ASSERT( image.isNull() == false);
 
	QLabel* label1 = new QLabel;
	label1->setPixmap( QPixmap::fromImage( image));
	layout->addWidget( label1);
 
	ui.scrollArea->setBackgroundRole(QPalette::Dark);
	ui.scrollArea->setWidget( widget);
}

TestScrollArea::TestScrollArea(QWidget *parent, Qt::WFlags flags)
	: QMainWindow(parent, flags)
{
	ui.setupUi(this);
	
	QWidget* widget = new QWidget;
	QVBoxLayout* layout = new QVBoxLayout( widget);

	QImage image("D:\\data\\photo\\me\\bg2009.jpg");
	Q_ASSERT( image.isNull() == false);

	QLabel* label1 = new QLabel;
	label1->setPixmap( QPixmap::fromImage( image));
	layout->addWidget( label1);

	ui.scrollArea->setBackgroundRole(QPalette::Dark);
	ui.scrollArea->setWidget( widget);
}

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This code was placed to the main window constructor and it worked ok (image displayed). Then I created QScrollArea child class and moved the code to its contructor:

TestImageViewer::TestImageViewer(QWidget *parent)
	: QScrollArea(parent)
{
	QWidget* widget = new QWidget;
	QVBoxLayout* layout = new QVBoxLayout( widget);
 
	QImage image("D:\\data\\photo\\me\\bg2009.jpg");
	Q_ASSERT( image.isNull() == false);
 
	QLabel* label1 = new QLabel;
	label1->setPixmap( QPixmap::fromImage( image));
	layout->addWidget( label1);
 
	setBackgroundRole(QPalette::Dark);
	setWidget( widget);
}

TestImageViewer::TestImageViewer(QWidget *parent)
	: QScrollArea(parent)
{
	QWidget* widget = new QWidget;
	QVBoxLayout* layout = new QVBoxLayout( widget);

	QImage image("D:\\data\\photo\\me\\bg2009.jpg");
	Q_ASSERT( image.isNull() == false);

	QLabel* label1 = new QLabel;
	label1->setPixmap( QPixmap::fromImage( image));
	layout->addWidget( label1);

	setBackgroundRole(QPalette::Dark);
	setWidget( widget);
}

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Now I see nothing except a grey rectangle. What I'm doing wrong?

[mattc]

The way you create your layout is odd, why are you passing the widget as parent? Usually, you want to create the layout with no parent and then call:

widget->setLayout(layout);

widget->setLayout(layout);

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See code here:
http://doc.trolltech.com/4.6/qvboxlayout.html#details

edit: oops, I just read you can pass the widget as parent. However, setLayout() is worth a try :-)

[Coises]

Now I see nothing except a grey rectangle. What I'm doing wrong?

Just a possibility:

Are you sure that when you created the TestImageViewer class, you made the corresponding changes (presumably in Qt Designer) so that ui.setupUi is constructing a TestImageViewer where it used to construct a plain QScrollArea?

[agaf]

Just a possibility:

Are you sure that when you created the TestImageViewer class, you made the corresponding changes (presumably in Qt Designer) so that ui.setupUi is constructing a TestImageViewer where it used to construct a plain QScrollArea?

Yes, that was I checked first. To say the truth in the first case "empty" TestImageViewer is used as well