How to set the QTabWidget background image when there is not any widget page

[Hanson]

@JonB Emm, I think you misunderstood my thought.The right widget is the QTabWidget that has no any page,and I want to show the background image when this QTabWidget show first time and without any page.

[Hanson]

@JonB And the left side QTabWidget has nothing to do with this question.

[JonB]

@Hanson said in How to set the QTabWidget background image when there is not any widget page:

@JonB And the left side QTabWidget has nothing to do with this question.

That's really helpful to say now, it's as clear as mud! I previously asked for clarification.

So, I don't know, did you try setting the QTabWidget itself's background instead of that for any "pages"?

[Axel Spoerl]

An empty tab doesn’t show anything, neither does an empty widget, as @JonB said.
If you want to show an image to represent an empty default, populate the empty tab with a label that shows the desired image.

[JonB]

@Axel-Spoerl said in How to set the QTabWidget background image when there is not any widget page:

populate the empty tab

My impression is that OP is saying the QTabWidget has 0 tabs.
In that situation I'm not even sure what area the QTabWidget occupies, it may not even be the red frame area shown in the pic?

[CPPUIX]

@JonB I thought the same thing, so I made this MRE based on what I guess OP needs:

//this is a container widget
QWidget *w = new QWidget();
QVBoxLayout *l = new QVBoxLayout(w);

QPushButton *b = new QPushButton("add",w);
QPushButton *b1 = new QPushButton("remove",w);
QTabWidget *t = new QTabWidget(w);

//here I'm setting QTableWidget background image before it is displayed
t->setStyleSheet("background-image: url(:/green.png);");

l->addWidget(b);
l->addWidget(b1);
l->addWidget(t);

//here I'm making it detect when all tabs are removed so It can set a background image when it's empty
t->connect(t,&QTabWidget::currentChanged, [=]()
{
    if(t->currentIndex()==-1)
        t->setStyleSheet("background-image: url(:/green.png);");
    else
        t->setStyleSheet("");
});
//these are just buttons I used to add and remove tabs
b->connect(b,&QPushButton::clicked, [=]()
{
    t->addTab(new QWidget(),"Tab");
});

b1->connect(b1,&QPushButton::clicked, [=]()
{
    t->removeTab(t->count()-1);
});

w->show();

Here's how it functions:

@Hanson could you take a look at it, and answer the previous questions to clarify what you need?

[JoeCFD]

@Hanson I guess Tab1 and Tab2 are QTabWidget.

auto page2 = new QWidget( this );
tabWidget->addTab( page2, QString( "Tab2" ) );
You create a widget and set it as Tab2.

If you have created page2,
auto page2 = tabWidget->widget( 1 );

Then set a picture with stylesheet for icon_name.
page2->setStyleSheet(QStringLiteral("border-image: url(:/resources/images/%1)").arg( icon_name ) );

[shottercleve]

This post is deleted!

[Hanson]

@JonB Yes!I just want to set the QTabWidget itself's background instead of that for any "pages".

[Hanson]

@Abderrahmene_Rayene Yes.This is what I want.But can you set the background image when the QTabWidget show first without any pages.

[Hanson]

Thanks to everyone who answered.You really help me a lot.And Finally I found a solution what I want.
I found that the empty QTabWidget contains a QStackedWidget.

QList<QWidget*> widgets = ui->tabWidget_2->findChildren<QWidget*>();
for (auto wid : widgets)
{
	auto meta = wid->metaObject();
	qDebug() << meta->className();
	qDebug() << wid->objectName();
	qDebug() << "==============";
}

And there is the output

QStackedWidget
"qt_tabwidget_stackedwidget"
==============
QTabBar
"qt_tabwidget_tabbar"
==============
QToolButton
""
==============
QToolButton
""
==============

So I write a qss like this, and it really works.

QTabWidget>QStackedWidget#qt_tabwidget_stackedwidget
{
background-image: url(:/img/background.png);
}

With @Bonnie suggestion, it works perfectly.

@Bonnie said in How to set the QTabWidget background image when there is not any widget page:

for every widget added to the tabwidget, set autoFillBackground to true.

[Hanson]

Oh no!I found the qss also affect all the pages in the QTabWidget :(

[Bonnie]

@Hanson One way to solve this: for every widget added to the tabwidget, set autoFillBackground to true.
Or you can just dynamically set the qss, when there's no widget, clear the qss, when there's any, set the qss.

[Hanson]

@Bonnie Nice!It works.Thank you very much!