Below is my code, I have resolved to my Question .Al last i got solution with help of stack overflow team .It is possible to play animation (.gif file) on main thread if you are doing long task in worker thread.And other things is as with official doc QPixmap is does not supporting in worker thread .So i hope guys it will be help for Qt developer.

int worker::do_Work()
{
int i =0;
while (i<1000000)
{
qDebug()<<":count *i=========>"<<i;
i++;
}
qDebug()<<"Worker process finished in Thread "<<thread()->currentThreadId();
emit finished();
}

int mywidget::popup()
{
ui->label_2->setStyleSheet("background-color:rgb(85,255,127);border-radius:10px");
ui->label_2->setWindowFlags(Qt::FramelessWindowHint);
ui->label_2->setText("Please Wait..");
ui->label_2->setAutoFillBackground(true);
QMovie *movie = new QMovie(":images/loader.gif");
ui->label_2->setMovie(movie);
ui->label_2->show();
qDebug()<<"labele show";
movie->start();

myWorker = new worker;
WorkerThread = new QThread;
myWorker->moveToThread(WorkerThread);

connect(WorkerThread, SIGNAL(started()), myWorker, SLOT(do_Work()));
WorkerThread->start();
connect(myWorker, SIGNAL(finished()), ui->label_2, SLOT(close()));
return 0;
}


1 Answer
1

If the main loop is busy because it is processing events, it will not update the GUI (because the GUI is managed by the main thread).

When you have long processing tasks, execute them in a different thread (or accept to freeze your GUI).

As I said, the GUI is and must be managed in the main thread :

GUI Thread and Worker Thread

As mentioned, each program has one thread when it is started. This
thread is called the "main thread" (also known as the "GUI thread" in
Qt applications). The Qt GUI must run in this thread. All widgets and
several related classes, for example QPixmap, don't work in secondary
threads. A secondary thread is commonly referred to as a "worker
thread" because it is used to offload processing work from the main
thread.

QPixmap

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