Unsolved QVboxLayout does not works as expected

[MasterBLB]

Hello fellow Qt developers

I have spotted very strange behavior of QVboxLayout. I add it to a widget like this:

InventoryWidget::InventoryWidget(QWidget *parent)
: InventoryBase(parent)
{
    pen = QPen(Qt::white, penSize);

    inventoryLayout = new QVBoxLayout(this);
    inventoryLayout->setContentsMargins(0, 0, 0, 0);
    inventoryLayout->setSpacing(0);
}

and then fill it with items:

void InventoryWidget::setupInventory(const QVector<const InventoryItem*> &inventory)
{
    int offset = 0;
    for (const InventoryItem *item : inventory)
    {
        InventoryItemWidget *newItem = new InventoryItemWidget(item, this);
        inventoryLayout->addWidget(newItem);
    }
    inventoryLayout->addStretch();
}

The issue is that QSpacer added by addStretch() is moved outside the InventoryWidget into its parent, and placed between Strip Stuff button and InventoryWidget.

Legend:
red rectangle - widget the question is about
green rectangle - layout which contains one or two MechPartWidgets, and spacer. You can see it in "MechDesign in Designer"
blue rectangle - MechPartWidget, you can see how it is designed in MechPartWidget in Designer

With layout - wrong:

Without layout - good:

MechPartWidget:

MechDesignWidget:

[mrjj]

Hi
It all looks pretty fine
Could you try to do
qApp->setStyleSheet("QWidget { border: 1px solid red; }");

so we can see where the various Widgets ends ?
Im not convinced that a spacer can jump out of its Widget/layout so i think something else
is going on.

[MasterBLB]

@mrjj sure mate, here they are:

An explanation - blue rectangle is actual border of InventoryWidget, as it has reimplemented paintEvent like:

void InventoryWidget::paintEvent(QPaintEvent *event)
{
    QWidget::paintEvent(event);
    QPainter painter(this);
    painter.setBrush(QBrush(Qt::darkGray));
    painter.setPen(pen);
    //painter.setRenderHint(QPainter::Antialiasing, true);

    painter.drawRect(penSize/2, penSize/2, slotWidth, slotsCount * slotHeight);
    for (int cnt = 1; cnt < slotsCount; cnt++)
    {
        painter.drawLine(penSize/2, cnt * slotHeight + penSize/2, slotWidth, cnt * slotHeight + penSize/2);
    }

    if (hasAddEquipmentDialogOn)
    {
        painter.setPen(QPen(Qt::blue, 4));
        painter.setBrush(Qt::NoBrush);
        painter.drawRect(2, 2, width() - 4, height() - 4);
    }
}

[mahd96]

i has some in experiences like this and i solved it by adding more QSpacer items. so you may try adding more strech.
in my case in happened when my widget size was too big in some big monitors.

[MasterBLB]

So many Qt experts here, yet no one can help...tough luck :/

[SGaist]

Hi,

Might be a silly question but shouldn't you add the stretch only if you have something in the inventory vector ?

[MasterBLB]

Hey SGaist
If I don't add stretcher these items (M Lasers) are scattered evenly among all the space of InventoryWidget, and I'd like them to be aligned to top.
Looks like I'll have to manually calculate and set offsets for InventoryItemWidgets...

[mrjj]

Hi
The red border didnt show anything useful sadly.
I think the spacer thats already in the visual UI form, is sometimes
in wrong place and produce the space.
But hard to debug as spacers cant be seen.
It could also be the space above Strip stuff is sometimes not used/compressed or
something like that.