Deleting data from a QScrollArea

mar0029

@mrjj Thank you! I used a ruler and everything!

I would like to keep everything up to the red a.k.a. my QVBoxLayout
What happens to all of the QHboxLayout and all the widgets within those Layouts, I don't care.

mrjj

Hmm.
Ok. I was kinda planning
to just create new widget with a boxlayout and call
setWidget on ScrollArea.
But u say this crashes?

mrjj

Hi again
i made same layout in designer
I kill them this way


void MainWindow::on_btremove_released() {

  QList<QWidget*> allSubLayouts = ui->innerwidget->findChildren<QWidget*>(QString(), Qt::FindDirectChildrenOnly);
  int size = allSubLayouts.size();
  // take all out
  while (( ui->innerwidget->layout()->takeAt(0)) != 0)
    // killem
    for(int i = 0; i < size; i++) {
      qDebug() << allSubLayouts[i]->metaObject()->className();
      delete allSubLayouts[i];

    }


}

U can check your self.
https://www.dropbox.com/s/auivviiv8tv7jfw/myscroll.zip?dl=0
should be the same you want if i read ur fine drawing correct :)
Note the Qt::FindDirectChildrenOnly flag!

mar0029

@mrjj
I don't want to delete my QWidget because I would have to dynamically create a new one each time I loaded a new file and I really don't want to deal with that.

I'm making some progress with this:

    while((child = mainVbox->layout()->takeAt(0)) != 0)
        {
        delete child;
        }

but in the documentation it says that when I delete a layout, I have to delete the widgets separately.
So I'm trying to make a list of the widgets found within the sublayout and then delete from there but it's not working.

mrjj

Did u try the sample?
It leaves the QWidget and layout but kills all it members.

mar0029

@mrjj oh my where did you find that flag? How did you know you could do ui->innerWidget->findChildren<QWidget*>(String(), Qt::FindDirectChildrenOnly); ??

mar0029

@mrjj Thank you for your help. I am unable to get it to work right now but I can see this achieving the goal. I will come back to it later today/tomorrow.

Thanks again!

mrjj

Hi
In the documentation for findChildren. I went looking as your
drawing made it very clear what u wanted. (kill all inner widgets)

So If you do it for your Widget (myWidget), it should do the same.
( i hope :)

you are welcome. I hope u get it to work.

mar0029

@mrjj
So here is what I've ended up doing.

I had been able to get a QList of the layouts in the main layout like so

 QList<QLayout *> allSubLayouts = mainVbox->findChildren<QLayout *>();

So I checked if that list was empty or not, basically seeing if it was the first time to use the program.

if(!allSubLayouts.empty())
{

    int size = allSubLayouts.size();
    for(int i = 0; i < size; i ++)
    {
        qDebug() << "this is what is at allSublayouts.at("<<i<<") " << allSubLayouts.at(i);


        for(int j = 0; j < allSubLayouts.at(i)->count(); ++j)
        {
            QWidget *w = allSubLayouts.at(i)->itemAt(j)->widget();
            if(w != NULL)
            {
                w->setVisible(false);
            }
        }
    }
}

Since I knew that there were layouts available, instead of using findChildren() I used allSubLayouts.at(i)->*itemAt*(j)->*widget*();

While this solves my problem of widgets and layouts overlapping in MainWindow, I don't know if it will cause a memory leak or will use up too much memory, since I'm not deleting any widgets/layouts.

mrjj

Hi

"allSubLayouts.at(i)->*itemAt*(j)->*widget*();"

made my brain hurt :)
Well since u are not deleting any widgets, u will use more and more memory,
but since they are still owned by layout, it will be free when application ends.