pls help. Need Qpainter to draw over a background image of mainwindow

[athulms]

can you pls provide me some code??

I have created a new class

#include <QtGui>
#include <QDebug>
 
class Frame : public QFrame{
    Q_OBJECT
public:
    Frame( QWidget * parent = NULL ) : QFrame(parent){
                setStyleSheet( "Frame{ background-image: url(plasma.png); }" );
    }
protected:
    void paintEvent( QPaintEvent * event ){
        QFrame::paintEvent(event);
        QPainter p(this);
        p.drawLine( rect().topLeft(), rect().bottomRight() );
        p.drawText( rect().center(), "works!" );
    }
};

#include <QtGui>
#include <QDebug>
 
class Frame : public QFrame{
    Q_OBJECT
public:
    Frame( QWidget * parent = NULL ) : QFrame(parent){
                setStyleSheet( "Frame{ background-image: url(plasma.png); }" );
    }
protected:
    void paintEvent( QPaintEvent * event ){
        QFrame::paintEvent(event);
        QPainter p(this);
        p.drawLine( rect().topLeft(), rect().bottomRight() );
        p.drawText( rect().center(), "works!" );
    }
};

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I have drawn the line in the subclass frame. Now how can i promote the frame over my mainwindow(ui)