Qt Scroll Area does not add in scroll bars

Hi guys I have to dynamically create push buttons depending on user inputs, therefore if user gives a large input number the widget containing the push buttons has to have the ability to scroll up and down. For this reason I am using QScrollArea. I generate the template in Qt designer and the UIC generates the code for me after which I add in my part which should handle dynamic creation of push buttons. However, I can not seem to get the vertical scroll bars to appear. Here is the relevant part of the code.

    verticalWidget = new QWidget(FWHMWorkflowDialog);
    verticalWidget->setObjectName(QString::fromUtf8("verticalWidget"));
    verticalWidget->setMinimumSize(QSize(150, 0));
    verticalWidget->setMaximumSize(QSize(150, 16777215));
    verticalLayout_5 = new QVBoxLayout(verticalWidget);
    verticalLayout_5->setObjectName(QString::fromUtf8("verticalLayout_5"));
    scrollArea = new QScrollArea(verticalWidget);
    scrollArea->setObjectName(QString::fromUtf8("scrollArea"));
    scrollArea->setMaximumSize(QSize(150, 16777215));
    scrollArea->setWidgetResizable(true);
    scrollAreaWidgetContents = new QWidget();
    scrollAreaWidgetContents->setObjectName(QString::fromUtf8("scrollAreaWidgetContents"));
    scrollAreaWidgetContents->setGeometry(QRect(0, 0, 130, 432));

    numberOfSlices = numberSlices;
    for (int i = 0; i < numberOfSlices; i++)
    {
        QWidget *horizontalWidget = new QWidget(scrollAreaWidgetContents);
        horizontalWidget->setMaximumSize(150,40);
        horizontalWidget->setGeometry(QRect(0, i*40, 150, 40));
        hWidgetList.push_back(horizontalWidget);

        QHBoxLayout *hLayout = new QHBoxLayout(horizontalWidget);
        hLayoutList.push_back(hLayout);
        hLayout->setSizeConstraint(QLayout::SetMinimumSize);
        hLayout->setContentsMargins(-1, 1, -1, 1);

        QPushButton *pushButton = new QPushButton(horizontalWidget);
        pushButtonList.push_back(pushButton);
        QString temp = QString("m_sliceButton").arg(i);
        pushButtonList[i]->setObjectName(temp);
        pushButtonList[i]->setGeometry(QRect(10, 20+i*40, 98, 27));
        hLayout->addWidget(pushButton);

        QCheckBox *checkBox = new QCheckBox(horizontalWidget);
        checkBoxList.push_back(checkBox);
        temp =  QString("m_checkBox").arg(i);
        checkBoxList[i]->setObjectName(temp);
        checkBoxList[i]->setEnabled(true);
        checkBoxList[i]->setGeometry(QRect(110, 20+i*40, 21, 22));

        hLayout->addWidget(checkBox);

    }

    scrollArea->setWidget(scrollAreaWidgetContents);
    //scrollArea->setWidgetResizable(true);

    verticalLayout_5->addWidget(scrollArea);

The output window always looks like the following.

In this example the input by the user is 25 however you can see that the 21st button is cut off and 4 other buttons are not visible.

The size window problem occurring after scroll functionality started working.

回答1:

You need to add your horizontalWidget to a vertical widget like so:

QVBoxLayout* vLayout = new QVBoxLayout();

for (int i = 0; i < numberOfSlices; i++)
{
    QWidget *horizontalWidget = new QWidget();
    vLayout->addWidget(horizontalWidget);
    ....
}
scrollAreaWidgetContents->setLayout(vLayout);

You second problem looks like it comes from this line:

scrollArea = new QScrollArea(verticalWidget);

You're adding scrollArea directly to verticalWidget, but to get it to lay out the way you want you need to put it in a layout. Try the following instead:

QVBoxLayout* l = new QVBoxLayout();
l->addWidget(sliceLabel); // or whatever you call it
l->addWidget(scrollArea);
l->addWidget(clearButton); // again, your name here
verticalWidget->setLayout(l);

回答2:

Try playing around with the QScrollBarPolicy.

http://doc.qt.digia.com/qt/qabstractscrollarea.html#horizontalScrollBarPolicy-prop

I'm guessing that the default behavior isn't working because there is something strange going on with layouts.