Image scaling is ignored when adding QLabel with image at runtime - qt

Question

I am trying to add a QLabel with an image to my GUI at runtime, but the scaling is ignored and the image expands to its full size (which is larger than the screen), ignoring the size constraints and not scaling the contents correctly.
The image should be fit into the bottom, left side of the window, as my GridLayout describes here:
headerPnl= new HeaderPnl();
buttonPnl = new ButttonPnl;
mainContentPnl = new QStackedWidget;
mainLayout = new QGridLayout;
mainLayout->setMargin(0);
mainLayout->setSpacing(0);
mainLayout->addWidget(headerPnl, 0, 0, 1, 7);
mainLayout->addWidget(mainContentPnl, 1, 0, 10, 6);
mainLayout->addWidget(buttonPnl, 1, 6, 10, 1);
mainLayout->setRowStretch(0,1);
mainLayout->setRowStretch(1,2);
mainLayout->setRowStretch(2,2);
mainLayout->setRowStretch(3,2);
mainLayout->setRowStretch(4,2);
mainLayout->setRowStretch(5,2);
mainLayout->setRowStretch(6,2);
mainLayout->setColumnStretch(0,1);
mainLayout->setColumnStretch(1,1);
mainLayout->setColumnStretch(2,1);
mainLayout->setColumnStretch(3,1);
mainLayout->setColumnStretch(4,1);
mainLayout->setColumnStretch(5,1);
mainLayout->setColumnStretch(6,1);
this->setLayout(mainLayout);
The header goes across the top, the button panel goes along the right side, and the rest of the screen is changing depending on the workflow of the application (ie what buttons are pressed, etc).
When necessary, my GUI replaces the widgets and updates the GUI like this:
void MainWindow::setContentPane(QWidget *content){
mainLayout->replaceWidget(contentPnl, content);
contentPnl = content;
}
void MainWindow::setButtonPanel(QWidget *buttonPanel){
mainLayout->replaceWidget(buttonPnl, buttonPanel);
buttonPnl = buttonPanel;
}
void MainWindow::configureWelcome(){
QLabel *welcomeLbl = new QLabel;
welcomeLbl->setObjectName("welcomeLbl");
welcomeLbl->setPixmap(QPixmap(":/images/welcome.jpg"));
welcomeLbl->setScaledContents(true);
CustomWidget *welcomeWidget = new CustomWidget;
QHBoxLayout *welcomeLayout = new QHBoxLayout;
welcomeLayout->addWidget(welcomeLbl);
welcomeWidget->setLayout(welcomeLayout);
setContentPane(welcomeWidget);
CustomWidget *buttonPnl = createWelcomeButtonPanel();
setButtonPanel(buttonPnl);
}
How can I make this image fit inside the GridLayout properly? It seems like when adding widgets to a layout that has already been set, the GUI doesn't know how to handle the size constraints from the GridLayout. Replacing the buttons works fine, but adding an image does not.
Side question: I have been trying to stay away from a QStackedWidget, as this application is designed for a lower power system, and it doesn't make sense to me to create all the possible screens and add them all to a QStackedWidget when the application starts. Instead I would rather use the resources when necessary, and only create all the GUI elements when I need to (ie, when the right buttons are clicked). Does that make sense?

Answer 1

Did you had a QSizePolicy to the widget containing the QGridLayout? I suggest an horizontal and vertical QSizePolicy::Fixed.
In your first code segment add :
this->setSizePolicy(QSizePolicy::Fixed,QSizePolicy::Fixed);