QFontDatabase::addApplicationFontFromData && addApplicationFont returns -1

[jyotinder]

I want to load hindi font form the resource. But whenever i tried use QFontDatabase::addApplicationFontFromData && addApplicationFont it returns -1 . Below is my code .

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    QFile res("fonts/raghu.ttf");
 
    if (res.open(QIODevice::ReadOnly) == false) {
                   qDebug()<<"error not able to load the file";
 
                    }
 
//File loaded sucessfully
qDebug()<<"File Information";
qDebug()<<"handle::"<<res.handle()<<"Size::"<<res.size()<<"\n";
 
//*QTextStream in(&res);
qDebug()<<res.readAll();
 
QByteArray data =res.readAll();
 
    int fontID = QFontDatabase::addApplicationFontFromData( data );
 
    if (fontID == -1 ) {
                    qDebug()<<"error";
     }
    else
      qDebug()<<fontID;
 
    ui->setupUi(this);
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    QFile res("fonts/raghu.ttf");

    if (res.open(QIODevice::ReadOnly) == false) {
                   qDebug()<<"error not able to load the file";

                    }

//File loaded sucessfully
qDebug()<<"File Information";
qDebug()<<"handle::"<<res.handle()<<"Size::"<<res.size()<<"\n";

//*QTextStream in(&res);
qDebug()<<res.readAll();

QByteArray data =res.readAll();

    int fontID = QFontDatabase::addApplicationFontFromData( data );

    if (fontID == -1 ) {
                    qDebug()<<"error";
     }
    else
      qDebug()<<fontID;

    ui->setupUi(this);
}

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Kindly guide me where i am doing wrong . Thank you