Painting Pixels in QGraphicsView

Hi

I am making a scanner such as this
http://spritesmods.com/?art=mouseeye

from the device, everything is ready. But when i tray to print this on QGraphicsView I have a memory leak...

Code:

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void MainWindow::parseFrame (QByteArray DATA){
 
 
    bool frameOK = true;
    QList <QByteArray> line = DATA.split('\n');
 
//DATA structure
//
//BO:
//DE: 2bits x movement, y movement
//SQ: 1bit Surface Quality 
//MI:  1bit
//MA: 1bit
//FR: 324bits ( SOF | Data_Valid | PD5 | PD4 | PD3 | PD2 | PD1 | PD0 ) where PDx intensity of pixel in gray scale
//EO:
 
 
    for (int w = 0 ; w < line.size() ; w++)
    {
        if ( line.at(w).startsWith("FR:") && frameOK ) //Jeżeli dane są ramką
        {
            QList <QByteArray> frame = line.at(w).split(':');
 
            if ( (frame.at(1).size() < 324) || (frame.at(1).size()>324 ))
            {
                qDebug()<<"Frame damaged :"<<frame.at(1).size();
                ramkaOK = false;
            }//IF
            else
            {
                scene->clear(); // !!!!!!!!
                quint8 col;
                quint16 pixelIndex;
                for( pixelIndex = 0 ; pixelIndex < 18*18 ; ){
                    col = (quint8)(frame.at(1)[pixelIndex] << 2 );
                    color->setRgb(col,col,col);
                    brush->setColor(*color);
                    //That section works well
                    scene->addRect( ((quint8)(pixelIndex/18))*7, //X
                                    (17 - (pixelIndex%18))*7,    //Y
                                    7,7,*pen,*brush );
                    //This section will leak memory, because I add data instead of overwriting
                    bigScene->addRect(((quint8)(pixelIndex/18))+X, //x + DELTA X
                                      (17 - (pixelIndex%18))+Y,    //y + DELTA Y
                                      1,1,*pen,*brush );
                }
            } //ELSE Frame OK
        }//FRAME
        if ( line.at(w).startsWith("DE:") ) //DELTA
        {
            QList <QByteArray> delta = line.at(w).split(':');
 
            dx = delta.at(1)[0];
            dy = delta.at(1)[1];
            if ( ((dx > -127) && ( dx < 128 )) &&
                 ((dx > -127) && ( dx < 128 )) ){
                X+=dx;
                Y-=dy;
            }
            else
            {
                qDebug()<< "DX DY damaged" ;
                frameOK = false;
            }
 
        } //IF DELTA
 
     //ui->currentView is a QGraphicView
     ui->currentView->setScene(scene); 
     // ui->bigView->setScene(bigScene); //This causes a memory leak
     ui->sourceQuality->replot();
     ui->minMaxVal->replot();
 
}

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My question is, how can I draw the big picture?