Qscrollarea does not scroll

[kabanek]

I'm trying to use scrollarea, but I don't get scrollbars.

In my constructor I have

ui->setupUi(this);
Canvas = new JCanvas;
ui->scrollArea->setWidget(Canvas);
Canvas->setGeometry(0, 0, 0, 0);

ui->setupUi(this);
Canvas = new JCanvas;
ui->scrollArea->setWidget(Canvas);
Canvas->setGeometry(0, 0, 0, 0);

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where JCanvas is my implementation of QLabel.

Next, I load a picture and then

QPixmap _image;
_image.load(_fileName);
_image = _image.scaledToWidth(_getSize.PictureWidth);
Canvas->setPixmap(&_image);
//...
qDebug()<<ui->scrollArea->geometry();
qDebug()<<_image.size();

QPixmap _image;
_image.load(_fileName);
_image = _image.scaledToWidth(_getSize.PictureWidth);
Canvas->setPixmap(&_image);
//...
qDebug()<<ui->scrollArea->geometry();
qDebug()<<_image.size();

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in the output for example I got

QRect(11,47 1498x1262)
QSize(1500, 1220)

so size of the pictura is bigger than my qscrollarea.

Here is a screenshot
zrzut ekranu1.jpg