Here is the code to make a QDeclarativeView based application transparent.
#include
#include
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QDeclarativeView view;
view.setSource(QUrl::fromLocalFile(“myqmlfile.qml”));
view.setAttribute(Qt::WA_TranslucentBackground);
view.viewport()->setAutoFillBackground(false);
view.show();
return a.exec();
}