HOW TO DISPLAY A RECTANGLE ON AN IMAGE on a label

[qt_user]

I have already made a video player(it runs different frames according to a timer) on a "QLabel"(not a QScrollArea)......now I have added another functionality that when the "process" button is clicked, the images are displayed along with some rectangles......For this I have used QPainter class's drwaPixel() and drwaRectangle() functions.................but both the functions are not displaying anything on the Label..........Here is the part of the code for the newer(process) functionality..........

void VideoDisplayer::processNextPicture()
{
 
    if((i >= startFrameMarkerPosition)&&(i < endFrameMarkerPosition))
	 {    
		//videoLabel->setPixmap(QPixmap(localFileName.at(i)));
//I used this function for the earlier case(normal video display without process functionality) and it works fine but it can't be used now otherwise the drawRectangle() function doesn't work over it
 
                  // QFrame::paintEvent(event);
 
		QPainter painter(videoLabel);
 
               painter.drawPixmap(0,0,400,400,QPixmap(localFileName.at(i)));
      //painter.drawPixmap(0,0,100,100,QPixmap(":/images/frame0000.png"));
 
               int x,y,w,h;
               x=100; y=200; w=80;h=60;
               painter.setPen(Qt::red);
                painter.drawRect(x,y,w,h);
                videoLabel->adjustSize();
		//videoLabel->setScaledContents(true);
		localSlider->setValue(i);
		videoLabel->show();
		i++;
 
		}

void VideoDisplayer::processNextPicture()
{
  
    if((i >= startFrameMarkerPosition)&&(i < endFrameMarkerPosition))
	 {    
		//videoLabel->setPixmap(QPixmap(localFileName.at(i)));
//I used this function for the earlier case(normal video display without process functionality) and it works fine but it can't be used now otherwise the drawRectangle() function doesn't work over it
		
                  // QFrame::paintEvent(event);

		QPainter painter(videoLabel);
		
               painter.drawPixmap(0,0,400,400,QPixmap(localFileName.at(i)));
      //painter.drawPixmap(0,0,100,100,QPixmap(":/images/frame0000.png"));

               int x,y,w,h;
               x=100; y=200; w=80;h=60;
               painter.setPen(Qt::red);
                painter.drawRect(x,y,w,h);
                videoLabel->adjustSize();
		//videoLabel->setScaledContents(true);
		localSlider->setValue(i);
		videoLabel->show();
		i++;
		
		}

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This code displays nothing on the label
I have also tried using the paintEvent function by defining it with the similar contents and calling it in place of the above code by repaint();This showed me that the paint function is getting called but the drawRectangle() and drawPixmap() on a QLabel are the real culprits.......please suggest a solution......thanx in advance