How to add a Backrgound Image on my QMainWindow

Victor Delattre

Hi! Im new to Qt and Im struggling on how to do this,
I tried two methods but none of them worked.
The methods are here:

(I don't use them directly in the QMainWindow constructor because I don't want the background to be definitive in my window)
Thank you for your help!!

JonB

@Victor-Delattre
Please paste code, not show screenshots.

For background palette I think you need to set setAutoFillBackground(true) on any widget using it.

For style sheet, you are using a rule for MainWindow, but you don't have any widget with that name. QMainWindow or MainMenu might work for you as those are your classes.

Victor Delattre

@JonB Hi thank you for your answers!
I tried them but I still have the problem.
WIth Palette now it changes the background (was default grey now it's black) but I don't have my background image.
WIth StyleSheet either with QMainWindow or MainMenu it does nothing.
Pasting the code here:
On main:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    MainMenu Fenetre_Principale;
    Fenetre_Principale.lancerJeu();

    return app.exec();
}

On MainMenu.cpp:

MainMenu::MainMenu(QWidget *parent) : QMainWindow(parent)
{
    setFixedSize(largeur, hauteur);
    setWindowTitle("Badlands Cities");
    setWindowIcon(QIcon(":/Images/icon.jpeg"));
}

void MainMenu::lancerJeu()
{
    Bouton_Play = new CustomButton("Jouer", this);
    Bouton_Play->setDefault(true);
    Bouton_Play->move(pour_larg*10, pour_haut*25);

    Bouton_Quit = new CustomButton("Quitter", this);
    Bouton_Quit->move(pour_larg*10, pour_haut*50);

    //First Method with QPalette:
    /*
    setAutoFillBackground(true);
    QPixmap bkgnd(":/Images/MenuBackground.jpeg");
    bkgnd = bkgnd.scaled(this->size(), Qt::IgnoreAspectRatio);
    QPalette pal;
    pal.setBrush(QPalette::Window, bkgnd);
    setPalette(pal);
    */

    //Second Method with StyleSheet:
    /*
    QString Sheet = R"(
        MainMenu {
            border-image: url(":/Images/MenuBackground.jpeg") 0 0 0 0 stretch stretch;
    })";
    setStyleSheet(Sheet);
    */
    //Or:
    /*
    QString Sheet = R"(
        background-image: url(":/Images/MenuBackground.jpeg");
        background-position: center;
    )"
    CentralWidget()->setStyleSheet(Sheet);
    */

    this->show();

    QObject::connect(Bouton_Quit, SIGNAL(clicked()), qApp, SLOT(quit()));
    QObject::connect(Bouton_Play, SIGNAL(clicked()), this, SLOT(lancerMenu()));
}

Victor Delattre

@Victor-Delattre Can someone help me?
All I want is to use an image on the background of my window !

Bonnie

Does you app correctly show the window icon you've set?
I feel like it didn't load the jpeg picture successfully.

After

QPixmap bkgnd(":/Images/MenuBackground.jpeg");

check the value of bkgnd.isNull().

J.Hilk

@Victor-Delattre the palette version works just fine for me

Victor Delattre

@Bonnie
Yes my Icon is correctly displayed,
I don't know how to print the bkgnd.isNull() value but I understand what you were talking about.
What do I have to do to get access to this value in Qt Creator?
Btw I will try to change the image that is loaded, maybe it doesn't fit with Qt.
Thanks for your answer !

Victor Delattre

@Bonnie Alright!
When I change my Background Image it works!
Thanks for your answers all!