Linux/BEAGLEBK: how to display image full screen using qt 5 in lcd using beaglbne

QPixmap background("test.png");
background = background.scaled(this->size(), Qt::IgnoreAspectRatio);
QPalette palette;
palette.setBrush(QPalette::Background, background);
this->setPalette(palette);

QEventLoop loop;
QTimer::singleShot(1000, &loop, SLOT(quit()) );
loop.exec();

QPixmap background1("test1.png");
background1 = background1.scaled(this->size(), Qt::IgnoreAspectRatio);
QPalette palette1;
palette1.setBrush(QPalette::Background, background1);
this->setPalette(palette1);

QEventLoop loop1;
QTimer::singleShot(1000, &loop1, SLOT(quit()) );
loop1.exec();

QPixmap background2("test2.png");
background2 = background2.scaled(this->size(), Qt::IgnoreAspectRatio);
QPalette palette2;
palette2.setBrush(QPalette::Background, background2);
this->setPalette(palette2);