How to Qt Screen Capture using GrabWindow

[Qt_Bg]

Hi,

I am new to qt and programming world and please help me with this problem. I am runnign Qt on VxWorks and trying to capture Qt Window screen using grabWindow.

below is the function that I used. When I run, it prints the debug msg but does not generate any files.
Please correct me if I made any mistake.

Also how to I change the path where the file is saved?

@void ScanControlInterface::TopDisplay_Capture( )
{
QPixmap capture = QPixmap::grabWindow(QApplication::desktop()->winId(),0,0,QApplication::desktop()->width(),QApplication::desktop()->height());
QByteArray ptrImgRawData;
ptrImgRawData.clear();
QBuffer buffer(&ptrImgRawData);
buffer.open(QIODevice::WriteOnly);
capture.save(&buffer,"PNG");

qDebug ("ScanControlInterface::Screen captured");

}@