How To Incorporate Progress Bar In Program

[deekayt]

I see this facility of using the progress bar in Qt 4
How to use it in the program.

Suppose I have a program as shown by the code below where
in cjpeg.exe is lauched as a separate process. Can I show the progress bar till the time

*QProcess *P1 =new QProcess(this) ;
		 	QStringList s2;   
	 	 	s2 << "-steg" << "coded.txt" << "-q" << ui.compressionspinBox->text() << "cleanimage.ppm" << ui.jpeglineEdit ->text() ;
		 	P1->setReadChannelMode( QProcess::MergedChannels );
			P1->start(("cjpeg.exe"),s2); 
		 	P1->waitForFinished();

*QProcess *P1 =new QProcess(this) ;
		 	QStringList s2;   
	 	 	s2 << "-steg" << "coded.txt" << "-q" << ui.compressionspinBox->text() << "cleanimage.ppm" << ui.jpeglineEdit ->text() ;
		 	P1->setReadChannelMode( QProcess::MergedChannels );
			P1->start(("cjpeg.exe"),s2); 
		 	P1->waitForFinished();

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the cjpeg.exe does the work.
Where all do I have to make the changes .I mean in pro file, header file
and will there be some private slot for this .