How to set QScrollArea centralWidget ?

sonichy

I need QScrollArea.size fit MainWindow.size when resize.

MainWindow
{
    resize(600,400);
    QWidget *widget = new QWidget;    
    widget->setMinimumSize(1000,260);
    setCentralWidget(widget);
    QScrollArea *scrollArea = new QScrollArea(this);
    scrollArea->setWidget(widget);
    scrollArea->setFixedSize(500,260);
}

替代文字

jsulm

@sonichy said in How to set QScrollArea centralWidget ?:

scrollArea->setFixedSize(500,260);

Then why do you set fixed size?

sonichy

@jsulm If scrollArea do not setFixedSize, the scrollArea collapse.
替代文字

jsulm

@sonichy Because you did not put your scroll area in a layout...

SGaist

Hi,

What don't you set the QScrollArea as central widget of your QMainWindow ?

JonB

@SGaist
I'm interested: is the code as stands "allowed"? QMainWindow has its centralWidget set to a widget, and then the QScollArea sets as its widget the QMainWindow::centralWidget. So presently the scroll area has been placed "outside" the main window's central widget. We have separate QMainWindow->QWidget and QScrollArea->QWidget. Are you allowed to create a QScrollArea and then just "put it on" some existing widget in the hierarchy (without actually inserting it into the hierarchy so that it becomes QMainWindow->QScrollArea->QWidget)?

SGaist

You can have floating widgets. The thing that is wrong here is that "widget" is set as the QMainWindow and as the QScrollArea "central widget". From the description it should just be:

Create widget
Create QScrollArea
Set widget in QScrollArea
Set scroll area as QMainWindow central widget

JonB

@SGaist
Absolutely, that is what @sonichy should do. That is hierarchy QMainWindow->QScrollArea->QWidget.

But from what he originally wrote and what you say. if I have an existing hierarchy of widgets, if I feel like it I am allowed to just go QScrollArea::setWidget() to some widget already there, without actually inserting my QScrollArea, and that is allowed? I can add scrolling to any widget that way and it works?

SGaist

Some widget already inherit from QScrollArea, so no need for them but otherwise that's the idea yes.

sonichy

@SGaist Solved!

setCentralWidget(scrollArea);