qwidget reports incorrect width value

[user4592357]

i have such a class

class MyWidget : public QWidget
{
/// ...
};

then i add widgets to a hbox layout, and set thay layout to MyWidget object.
i want MyWidget widget to have the width of a widget contained in it.
so i overrode size hint:

QSize MyWidget::sizeHint() const
{
    // use the width of the first widget in the frame
    if (auto pLayout = layout())
    {
        auto pItem = pLayout->itemAt(0);
        //std::cout << pItem->widget()->width() << std::endl;
        if (pItem && pItem->widget())
            return QSize{ pItem->widget()->width(), QWidget::sizeHint().height() };
    }
    return QWidget::sizeHint();
}

now, pItem->widget()->width() always reports the same value no matter what size the widget is. what's the problem???

[mrjj]

@user4592357
Hi
If you call pItem->widget()->width() while the inner widget
is not visible, it might not report actual size. ( layout are not calculated yet )
You can try use the ShowEvent instead or
use
layout->invalidate();
layout->activate();
to try to force layout to be calculated before shown.

[user4592357]

this didn't work, i get the same result:

QSize MyWidget::sizeHint() const
{
	// use the width of the first widget in the frame
	if (auto pLayout = layout())
	{
		auto pItem = pLayout->itemAt(0);
		//std::cout << pItem->widget()->sizeHint().width() << std::endl;
		if (pItem && pItem->widget())
		{
			pLayout->invalidate();
			pLayout->activate();
			return QSize{ pItem->widget()->width(), QWidget::sizeHint().height() };
		}
	}
	return QWidget::sizeHint();
}

and i don't get how i'd use the inner widget sizes in showEvent()

[mrjj]

Hi
Hmm ok. I did something similar and that worked but i cant spot the difference.
Well try
pItem->widget()->width()
in ShowEvent to see if that even report expected size.

Also if MyWidget is a layout, then layout set size of it.
Unless you set MinimumSize for MyWidget
It will ignore resize / set Geometry.
Also sizeHint is just suggested size but if innner widget is also in a layout, then
om not sure this logic can even work. ( as inner widget then follow outer widget)
So something about this setup confuses me.

[user4592357]

yes, inner widget has min size set
and in showEvent inner widget still has the same size as before.

[mrjj]

@user4592357
So it does not report the minimumSize for the inner widget?

[user4592357]

no, it reports a little big larger, like 12px larger.
also, i have set setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Minimum);

p.s. i solved this another way. thanks for helping