QScrollArea stops limiting parent QDialog size

Cerno_b

I am using Qt5 with PySide2

I am experiencing some behavior that is different from what I would expect. Would anyone be able to clarify if I am misunderstanding something?

As soon as I add a QScrollArea to a QDialog, I lose the ability to constrain the dialog's maximum size by the scrollbar contents' minimum size. This is expected behavior from a QScrollArea I think, but it persists when I switch the scrollbars off, which is not what I would expect.

My setup is fairly simple:

In Designer, create a new QDialog
Add a QListWidget
Set the dialog's layout to vertical
Set the list widget's minimum width to 600

Run the code. I can now resize the dialog, but I can't make it smaller than the list widget's size allows. This is what I expected.

Now add some changes:

Place a QScrollArea on the QDialog
Move the list widget to the scroll area
Set the scroll area's layout to vertical

Run the code again. The dialog can now be resized to be smaller than the list widget's size allows and a scrollbar appears when I do. This is also what I expected.

One final change:

Set the scroll area's horizontal scroll bar policy to ScrollBarAlwaysOff

Run the code.

Behavior: The same as with the scrollbar enabled (I can make the dialog smaller than the list widget allows). The only difference is that the scrollbar is not shown.
Expected: The switched-off scroll bar enforces the dialog's maximum size to obey the list widget's minimum width as it would in the first example.

So what I am looking for is a QScrollArea that behaves exactly like a QScrollArea in vertical direction, but that behaves exactly as if it did not exist in horizontal direction.

I am trying to avoid doing any manual calculations on the window size if possible.

Is this a limitation in Qt or did I miss a setting that would allow getting this behavior?

SGaist

Hi,

If you want to achieve that you have to set the constraint yourself on the QScrollArea width when you hide the scrollbar.

Cerno_b

@SGaist Thanks for your input.

Can you clarify what you mean with "set the constraint"? Do you mean I need to limit the QScrollArea's width at some magic number? Because that's what I wanted to avoid.

I was looking for a solution that allows auto-formatting, but not the way a QScrollArea does but rather the way a QWidget does it, so I get the QScrollArea behaviour in one direction and the QWidget behaviour in the other direction.

And maybe clarification: Is this behaviour by design? I would kind of expect that a disabled scroll bar would not replicate the resizing behaviour as if a scroll bar was present, or is there a use case I am missing?