Qt Set Background image

Qlabel

Qpixmap pixmap ("Background.png");
Setpixmap (pixmap);      The picture is not adaptive to the size of the control    or the size of the picture

Setstylesheet ("Qlabel{border-image:url (background.png);}"); The default picture is self-adapting to the label size   

Qpushbutton

Setstylesheet ("Qpushbutton{border-image:url (background.png);}");   Ditto

Widgets

Setautofillbackground (TRUE); Some documents say add this  , meaning unknown
qpalette palette;
Qpixmap pixmap ("Background.png");
Palette.setbrush (Backgroundrole (), Qbrush (Pixmap));
This->setpalette (palette);  Picture size and widget size if the picture size is small,  it will be repeated arrangement

program icon

Setwindowicon (Qicon ("background.png"));

Background color

Setstylesheet ("background-color:red");