what Function use for Maximize the screen in QML?

I want to create an app that when it's maximize the background image and the image that are over the background also maximize. Which function that is used in QML for Maximize the app? Attachment 8432

To maximize the view, you need to call QWidget::maximize() so you can't do it from within QML. You need to export a C++ function that will call maximize() for you and then call it from QML.

I am new to QML. If I create a file from C++, so how can I call function from C++ file to QML?