qt如何实现一个渐隐窗口呢？就是比如说开启的时候他是从上往下渐渐显示的，关闭的时候从下往上渐渐小时的
http://stackoverflow.com/questions/19087822/how-to-make-qt-widgets-fade-in-or-fade-out

Fade In Your Widget

// w is your widgetQGraphicsOpacityEffect *eff = new QGraphicsOpacityEffect(this);w->setGraphicsEffect(eff);QPropertyAnimation *a = new QPropertyAnimation(eff,"opacity");a->setDuration(350);a->setStartValue(0);a->setEndValue(1);a->setEasingCurve(QEasingCurve::InBack);a->start(QPropertyAnimation::DeleteWhenStopped);

Fade Out Your Widget

// w is your widgetQGraphicsOpacityEffect *eff = new QGraphicsOpacityEffect(this);w->setGraphicsEffect(eff);QPropertyAnimation *a = new QPropertyAnimation(eff,"opacity");a->setDuration(350);a->setStartValue(1);a->setEndValue(0);a->setEasingCurve(QEasingCurve::OutBack);a->start(QPropertyAnimation::DeleteWhenStopped);connect(a,SIGNAL(finished()),this,SLOT(hideThisWidget()));// now implement a slot called hideThisWidget() to do// things like hide any background dimmer, etc.

qt如何实现一个渐隐窗口呢（开启的时候他是从上往下渐渐显示）