Qt QHBoxLayout issue? - c++

Question

I use an extended QGroupBox as the widget for QDockWidget in my QMainWindow.
Here is the code snippet:
RzPlaneViewerControlPanelWidget::RzPlaneViewerControlPanelWidget(QWidget *parent) : QGroupBox(parent) {
// TODO Auto-generated constructor stub
init();
}
void RzPlaneViewerControlPanelWidget::init()
{
QHBoxLayout *hbox=new QHBoxLayout;
hbox->setSizeConstraint(hbox->SetMinimumSize);
hbox->setSpacing(0);
hbox->setStretch(1,0);
setMaximumHeight(50);
QScrollBar *scrollbar=new QScrollBar;
scrollbar->setOrientation(Qt::Horizontal);
scrollbar->setMouseTracking(true);
scrollbar->setFocusPolicy(Qt::StrongFocus);
scrollbar->setMinimum(0);
scrollbar->setSingleStep(1);
QLineEdit *qlineedit = new QLineEdit;
qlineedit->setMaximumWidth(60);
qlineedit->setReadOnly(true);
hbox->addWidget(scrollbar);
hbox->addWidget(qlineedit);
//hbox->addWidget(new )
setLayout(hbox);
}
Here is how I add this widget to QDockWidget :
RzPlaneViewerControlPanelWidget *controlPanel=new RzPlaneViewerControlPanelWidget ;
controlPanel->init();
QDockWidget controlPanelDockWidet=new QDockWidget;
controlPanelDockWidet->setAllowedAreas(Qt::BottomDockWidgetArea);
controlPanelDockWidet->setFeatures(QDockWidget::DockWidgetVerticalTitleBar);
controlPanelDockWidet->setWidget(controlPanel);
But the ScrollBar is not stretched as I expected -
Here's how it looks like -
This is what I want -

Answer 1

From a quick read, I'd try doing:
hbox->addWidget(scrollbar, 1);
The second (optional) argument to addWidget is the stretch factor. From the Qt docs:
If the stretch factor is 0 and nothing else in the QBoxLayout has a stretch factor greater than zero, the space is distributed according to the QWidget:sizePolicy() of each widget that's involved.
Also, note that your:
hbox->setStretch(1,0);
call does not have any effect, as it is setting the qlineedit's stretch factor to 0, but that's already the default.