Qt设置透明度

QWidget *w = new QWidget(this);

plt2.setColor(QPalette::Background, Qt::green);

 w->setPalette(plt2);

w->setGeometry(0,0,600,800);

w->setStyleSheet("background-color: rgb(255, 0, 0, 0.2);");


注：若设置背景属性失败，可尝试设置该属性解决，setAttribute(Qt::WA_StyledBackground);

GraphicsOpacityEffect *pOpacityEffect = new QGraphicsOpacityEffect(this);
pOpacityEffect->setOpacity(0.1);
ui->pushButton->setGraphicsEffect(pOpacityEffect);