How to play a video on a translucent QWidget?

[liyingzai]

#include "videoplayer.h"
#include <QtWidgets/QApplication>
#include "qboxlayout.h"
#include "qvideowidget.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QWidget *w = new QWidget;

w->setWindowFlags(Qt :: Window | Qt::FramelessWindowHint );
w->setAttribute(Qt::WA_TranslucentBackground, true);
w->setMinimumSize(300,200);

QVideoWidget *videoWidget = new QVideoWidget;
QBoxLayout *controlLayout = new QHBoxLayout;
controlLayout->setMargin(0);
controlLayout->addWidget(videoWidget);
w->setLayout(controlLayout);

QMediaPlayer mediaPlayer;
mediaPlayer.setVideoOutput(videoWidget);
mediaPlayer.setMedia(QUrl::fromLocalFile("C:/1.wmv"));
videoWidget->show();
mediaPlayer.play();

w->show();
return app.exec();

}

when two line w->setWindowFlags(Qt :: Window | Qt::FramelessWindowHint ); w->setAttribute(Qt::WA_TranslucentBackground, true); remove the movie show correctly.
somebody tell ,in this case i use a custom video widget and in paintEvent after createing QPainter painter(this); add
painter.setCompositionMode(QPainter::RasterOp_SourceAndNotDestination); but i use, it is No effect! Someone met?Someone met ?Someone solution?