View a List of QLabel

Ggwppino

Hi! I'm new to Qt and I want to create an application that has a list of hyperlink and RichTex that is displayed in Layout ui.
I Tried to use setItemWidget of listWidget but it create memoryLeak for every QLabel i have (rightly).

any advice or help?

mrjj

Hi
Then it seems like a false positive as you set a parent so they will be cleaned up but
if the parent live long then it will first be much later that might fool
valgrind.

Pl45m4

@Ggwppino said in View a List of QLabel:

setItemWidget of listWidget but it create memoryLeak for every QLabel i have

If you add new items to your QListWidget, you dont have memory leaks. The parent (ListWidget takes care of all child items)

Ggwppino

thanks for the reply, it reassures me.
actually valgrind does not notify me of any problems in the memcheck section but When i click any QLabel with hyperlink in my application output, appear a lot of Valgrind notification of Memory leaks writed in xml.

Pl45m4

@Ggwppino

What labels? Do you mean QListWidgetItems?

Ggwppino

i Need to show in Layout a List of hyperlink. QLabel has possibility for containing richtext, so I do:

ui->listWidget->setWidgetItem(item, myLabel)

In memcheck, valgrind doesn't warning me, but in Application Output there are a lot of Valgrind error.

mrjj

@Ggwppino
The docs don't say it takes ownership so try to give the Label a parent. ( as far as i could find)
I think it does own it but try and see if it stops the valgrind warnings.

auto label = new QLabel( ui->listWidget);
ui->listWidget->setItemWidget(ui->listWidget->item(0), label);

Also note that valgrind might not understand Qt system in all cases.
https://doc.qt.io/qt-5/objecttrees.html

Ggwppino

@mrjj thanks for the reply,

I'm already doing it this way

    void mainwindow::printHyperLink(QString in){
        QListWidgetItem *item;
        QLabel * myLabel;
        bool opened = in!="Error";
    
        if (opened)
        {
    
            item = new QListWidgetItem("");
            ui->listWidget1->addItem(item);
            myLabel = new QLabel(in, this);
            myLabel->setTextInteractionFlags(Qt::TextBrowserInteraction);
            myLabel->setOpenExternalLinks(true);
            ui->listWidget1->setItemWidget(item, myLabel);
        } else {
            item = new QListWidgetItem("Error");
            ui->listWidget1->addItem(item);
        }
    }

practically this function is called every time one of my threads finishes processing a link.

Could this create problems with valgrind?
I specify that the problem persists even if I manually add only one item in ListWidget in mainwindow.

mrjj

Hi
Then it seems like a false positive as you set a parent so they will be cleaned up but
if the parent live long then it will first be much later that might fool
valgrind.