Cannot get QScrollArea to work

Question

I have a QDeclarativeView that I want to put in a QScrollArea the problem is that the scrollarea does not work. It doesnt matter how big I set the declarative view. I do not get the scrollbar it is like it cant tell that the view need a scrollbar. If i dont set setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn); the scrollbar does not appear.

Parent are inserted in a borderlayout as the centralwidget – I use this layout http://qt-project.org/doc/qt-4.8/layouts-borderlayout.html

myWidgets *editWidget = new myWidgets(pathToExe,viewerMgr, this);
editWidget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);

Here is myWidget:

QScrollArea* scroll = new QScrollArea();
    view = new QDeclarativeView(this);
    view->setSource(QUrl::fromLocalFile(path));
    view->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);

    view->setResizeMode(QDeclarativeView::SizeViewToRootObject);
    scroll->setWidget(view);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setWidgetResizable(true);

I have tried different size on the content but it's like the qscrollview doesnt detect when my widget is bigger then the visible view of qscrollarea.

I found what the problem is, the scrollarea or content of scroll area is not restricted in size. If i set view->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored); to view->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed); I do get the scrollarea to work. But I cant use my zoom function. So I still have a problem to get this to work — Chaf

Chaf Chaf · Accepted Answer · 2013-10-22T12:58:22

I have solved this problem, I created a help class that holds the qscrollarea and the fix is to update qscrollarea viewport. here is the code for the helpwidget

testHelpWidget::testHelpWidget(QString path,viewerManager *cMgr, QWidget *parent)
: QWidget(parent)
{
QVBoxLayout *layout = new QVBoxLayout;
scroll = new QScrollArea(this);

testWidget = new testWidgets(path,cMgr,this);
testWidget->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
QObject::connect(testWidget,SIGNAL(zoomChanged()),this,SLOT(repaintZoom()));
scroll->setWidget(qmlWidget);
scroll->setWidgetResizable(true);
scroll->setAlignment(Qt::AlignLeft);
layout->addWidget(scroll);
setLayout(layout);
}

void testHelpWidget::repaintZoom(){
scroll->viewport()->updateGeometry();
scroll->viewport()->update();
scroll->update();
}

Code for zoom function in testWidget

void testWidgets::zoom(double scale){
double tmp = scale/1;
double reset = 1/previousScale;
if(scale == previousScale){
    return;
}

view->scale(reset,reset);
view->resize(view->sizeHint()*reset);

view->scale(tmp,tmp);
previousScale = scale;

view->resize(view->sizeHint()*tmp);
view->updateGeometry();
view->update();
emit zoomChanged();
}

Cannot get QScrollArea to work

1 Answers