I know that this is a very specific C++ and Qt related question, but maybe someone can help me, anyway ...
See the code below: I want to display an image within a scroll area. The view port of the scroll area shall have a defined initial size. That means, if the image's size is bigger than the initial size of the view port, scroll bars will be visible, otherwise not.
// create label for displaying an image QImage image( ":/test.png" ); QLabel *label = new QLabel( this ); label->setPixmap( image.toPixmap() ); // put label into scroll area QScollArea *area = new QScrollArea( this ); area->setWidget( label ); // set the initial size of the view port // NOTE: This is what I'd like to do, but this method does not exist :( area->setViewPortSize( QSize( 300, 300 ) );
It shall be possible to resize the whole application so that the view port will get another size than the initial one.
Unfortunatelly I was not able to find out, how to set the size of the view port. Qt's layout mechanism seems to set a default size for the view port, but up to now I was not able to change it. Setting a new size with
area->setMinimumSize( QSize( 300, 300 ) );
will actually set the demanded size, but then the scroll area looses the ability to get resized to a size smaller than 300x300.
I think that you are looking at the problem the wrong way. The QScrollArea is just a widget that you put in a frame or QMainWindow. The size of the widget is controlled by the layout of the widget that contains it.
Take a look at this example from Trolltech: Image Viewer Example
Is the scroll area the top level widget? If so, simply call
If it's inside a hierarchy you need to resize the toplevel appropriately (complex), or set the minimumSize of the area. You could also try to experiment with the LayoutPolicy - assuming the sizeHint is QSize(300,300) you can give it the appropriate size policy according to what's defined in https://doc.qt.io/qt-5/qsizepolicy.html#Policy-enum