How to add QGridLayout to QScrollArea?

TomNow99

Hi,

I have QGridLayout with 10 QLabels. After 5 seconds I will add to QGridLayout next QLabel, so after 5 minutes I will have many QLabels in QGridLayout. Each QLabel has FixedSize. I know that is impossible to have them in the screen at the same moment, so I would like to have Scroll Bar. I know that is QScrollArea class. I try something like that:

centralWidget()->setLayout(layout);
layout->addWidget(scrollArea);
scrollArea->setLayout(layoutWithQLabels);

But I don't get scroll bar and QLabels are overlap.

I would like something like that:

JonB

@TomNow99

QWidget *scrollWidget = new QWidget;
scrollArea->setWidget(scrollWidget);
scrollWidget->setLayout(layoutWithQLabels);

mrjj

Hi
Would it not be easier just to use QListWidget?
Its a list of text lines that can scroll already.

TomNow99

@mrjj I need QGridLayout

@JonB Thank you, but what with scrollArea?
Now I have:

    scrollWidget = new QWidget;
    area->setWidget(scrollWidget);
    scrollWidget->setLayout(layoutWithLabels);

    layout->addWidget(area);
    centralWidget()->setLayout(layout);

And I don't see any QLabels.

EDIT
I try setCentralWidget(area); but this doesn't work too...

SGaist

Hi,

Don't set a layout on a QScrollArea. Set it on the widget contained in the scroll area.

Then set the scroll area as central widget.

TomNow99

@SGaist Hi,
My code:

    layoutWithLabels = new QGridLayout;
    scrollWidget = new QWidget;
    area= new QScrollArea;
    area->setWidget(scrollWidget);
    scrollWidget->setLayout(layoutWithLabels);
    setCentralWidget(area);

and I add Widgets to layoutWithLabels. But I doesn't see any QLabels.

SGaist

Well, the code you show here does not contain the part related to the labels. The issue might be in what you did not post.

TomNow99

@SGaist This is my whole code:

 layoutWithLabels = new QGridLayout;
    scrollWidget = new QWidget;
    area= new QScrollArea;
    area->setWidget(scrollWidget);
    scrollWidget->setLayout(layoutWithLabels);
    setCentralWidget(area);


    for(int i=0;i<10;i++)
    {
        wektor.append(new QLabel("randomText"));
        wektor[i]->setStyleSheet("QLabel {background-color:red}");

        layoutWithLabels->addWidget(wektor[i],i,0, Qt::AlignRight);

        wektor[i]->setFixedSize(50,20);
    }

wektor is QVector<QLabel*>

SGaist

Just a silly idea: build the complete widget first so it has all its content in place and as last step create the scroll area and put the widget in.

TomNow99

@SGaist hmmm, it works, but there is a new problem.

Now my code looks like:

    layoutWithLabels = new QGridLayout;

    for(int i=0;i<30;i++)
    {
        wektor.append(new QLabel(QString::number(i)));
        wektor[i]->setStyleSheet("QLabel {background-color:red}");

        layoutWithLabels->addWidget(wektor[i],i,0);

        wektor[i]->setFixedSize(50,20);
    }
    scrollWidget = new QWidget;
    scrollWidget->setLayout(layoutWithLabels);
    area= new QScrollArea;
    area->setWidget(scrollWidget);

    setCentralWidget(area);

But if you read my first post I would like to add a new QLabel to QGridLayout after 5 sec. I have QTimer and slot:

void MainWindow::timeoutSlot()
{
    static int i=30;
    wektor.append(new QLabel(QString::number(i)));
    wektor[i]->setStyleSheet("QLabel {background-color:red}");

    layoutWithLabels->addWidget(wektor[i],i,0);

    wektor[i]->setFixedSize(50,20);
    i++;
}

and it add new QLabel, but look:
This is my app after start:

and this is my app after add new QLabels:

QLabels are overlap

SGaist

There's no need for that static i variable. You can use the vector size for your computation.

TomNow99

@SGaist Yeah, you are right with static :) But what with the main problem?

JonB

@TomNow99
I think QGridLayout's job is to fit everything. You have to give something a size/spacing to make it work. setRowMinimumHeight(int row, int minSize)? setSpacing(int spacing)?

TomNow99

@JonB I try setSpacing and setRow but not work :(

SGaist

Since you have your labels in on column, why not use a QVBoxLayout ?

mrjj

Hi
Tried your code and it worked?
(not including the static int )

alt text

  QTimer::singleShot(5000, [this, layoutWithLabels]() {
        wektor.append(new QLabel(QString::number( wektor.size()))  );
        wektor.last()->setStyleSheet("QLabel {background-color:blue}");

        layoutWithLabels->addWidget(wektor.last(), wektor.size(), 0);

        wektor.last()->setFixedSize(50, 20);
    });

TomNow99

Hello,
@SGaist You are right. I started from QVBoxLayout, but I had problem with Alingment QLabels in layout, so I use QGridLayout.

@mrjj Please repeat add QLabel many Times. Of course you can change 5 sec to 0.5 sec. When I use your code I get:

Bonnie

[EDITED]
Removed my previous answer.
I've found the solution:

layoutWithLabels->setSizeConstraint(QLayout::SetMinimumSize);

QLayout::SetMinAndMaxSize also works.

TomNow99

@Bonnie P E R F E C T! Thank you!

Thanks for all you:@mrjj @JonB @SGaist