QPropertyAnimation makes my widget disappear

[Donation]

I made a timer in my program, and I want to do some animation when timeout. So I used QPropertyAnimation, but here is a problem, when the function run, my widget disappeared. The function is like this:

What makes the problem? thank you.

[jsulm]

@Donation Can you please post your code as text instead of screen-shot?
Maybe your widget is just transparent when animation finishes?

[Donation]

@jsulm
here is my code

#include "Widget.h"
#include "ui_Widget.h"

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget),
    m_timer(new QTimer)
{
    ui->setupUi(this);
    connect(m_timer, SIGNAL(timeout()), this, SLOT(OnTimer()));
}

Widget::~Widget()
{
    delete ui;
}

void Widget::StartTimer()
{
    m_time = ui->lineEdit->text().toInt();
    m_past = 0;
//    m_isCheck = false;
//    m_isStartTime = true;
    ui->label->setText(QString::number((m_time - m_past)));
    m_timer->start(1000);
}

void Widget::OnTimer()
{
    m_past++;

    if(m_past != m_time)
    {
        ui->label->setText(QString::number((m_time - m_past)));
    }
    else
    {
        m_timer->stop();
        TimeOut();
    }

}

void Widget::SetTime(int time)
{
    m_time = time;
}

void Widget::TimeOut()
{
    this->setWindowFlags(Qt::WindowStaysOnTopHint);
    ui->label->setText("Time out!");
//    onShakeWindow();
    onTwinkle();
}

int Widget::alpha() const
{
    return m_alpha;
}

void Widget::setAlpha(const int alpha)
{
    m_alpha = alpha;
    QString strQSS = QString("color: rgb(0, 160, 230); background-color: rgba(10, 160, 105, %1);").arg(m_alpha);
    ui->label->setStyleSheet(strQSS);

}

void Widget::onShakeWindow()
{
    QPropertyAnimation *pAnimation = new QPropertyAnimation(this, "pos");
    pAnimation->setDuration(500);
    pAnimation->setLoopCount(2);

    int x = geometry().x();
    int y = geometry().y();
    x = 10;
    y = 10;

    pAnimation->setKeyValueAt(0, QPoint(x - 3, y - 3));
    pAnimation->setKeyValueAt(0.1, QPoint(x + 6, y + 6));
    pAnimation->setKeyValueAt(0.2, QPoint(x - 6, y + 6));
    pAnimation->setKeyValueAt(0.3, QPoint(x + 6, y - 6));
    pAnimation->setKeyValueAt(0.4, QPoint(x - 6, y - 6));
    pAnimation->setKeyValueAt(0.5, QPoint(x + 6, y + 6));
    pAnimation->setKeyValueAt(0.6, QPoint(x - 6, y + 6));
    pAnimation->setKeyValueAt(0.7, QPoint(x + 6, y - 6));
    pAnimation->setKeyValueAt(0.8, QPoint(x - 6, y - 6));
    pAnimation->setKeyValueAt(0.9, QPoint(x + 6, y + 6));
    pAnimation->setKeyValueAt(1, QPoint(x- 3, y - 3));
    pAnimation->start(QAbstractAnimation::DeleteWhenStopped);
}

void Widget::onTwinkle()
{
    QPropertyAnimation* pa = new QPropertyAnimation();
    pa->setTargetObject(this);
    pa->setPropertyName("alpha");
    pa->setDuration(5);
    pa->setLoopCount(5);
    pa->setKeyValueAt(0, 255);
    pa->setKeyValueAt(0.5, 100);
    pa->setKeyValueAt(1, 255);
    pa->start();
}

//void Widget::on_pushButton_clicked()
//{
//    if(m_isStartTime == false)
//    {
//        return;
//    }

//    m_isCheck = true;
//    m_isStartTime = false;
//}

void Widget::on_pushButton_2_clicked()
{
    StartTimer();
}

[J.Hilk]

@Donation I'm pretty sure alpha is not a valid property of a QWidget, you're probably looking for opacity

---

edit: nope, opacity does not exist either, one is supposed to use https://doc.qt.io/qt-5/qgraphicsopacityeffect.html

[Donation]

@J-Hilk
thanks for your help, but what about onShakeWindow(), it use pos as the property, and has the same problem with onTwinkle()

[J.Hilk]

@Donation
not for me, works perfectly fine.

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QWidget w;

    w.resize(100, 100);
    w.show();

    QPropertyAnimation *p= new QPropertyAnimation();
    p->setTargetObject(&w);
    p->setPropertyName("pos");
    p->setDuration(2000);
    p->setLoopCount(-1);
    int x = 100;
    int y = 100;
    p->setKeyValueAt(0, QPoint(x - 3, y - 3));
    p->setKeyValueAt(0.1, QPoint(x + 6, y + 6));
    p->setKeyValueAt(0.2, QPoint(x - 6, y + 6));
    p->setKeyValueAt(0.3, QPoint(x + 6, y - 6));
    p->setKeyValueAt(0.4, QPoint(x - 6, y - 6));
    p->setKeyValueAt(0.5, QPoint(x + 6, y + 6));
    p->setKeyValueAt(0.6, QPoint(x - 6, y + 6));
    p->setKeyValueAt(0.7, QPoint(x + 6, y - 6));
    p->setKeyValueAt(0.8, QPoint(x - 6, y - 6));
    p->setKeyValueAt(0.9, QPoint(x + 6, y + 6));
    p->setKeyValueAt(1, QPoint(x- 3, y - 3));
    p->start();

    return app.exec();
}

[Donation]

@J-Hilk
If I put these codes in main.cpp, it also works fine. But when I put into member function onShakeWindow(), the problem comes out.

[J.Hilk]

@Donation is your widget part of a layout?

[Donation]

@J-Hilk No, I only made one widget, and put some QPushButton and QLable on it.