Player practice 26 adding slider and window maximization

1. add to positioning
2. add controls , Modify name , Modify maximum value to improve precision

3.
In the class xplay2 Add

void Xplay2::timerEvent(QTimerEvent* e)
{
    
	long long total = dt.totalMs;
	qDebug() << "total: " << total << endl;
	if (total > 0)
	{
    
		// Currently decoded pts Divide by total pts, It's a ratio 
		double pos = (double)dt.pts / (double)total;
		qDebug()<< "pos: " << pos << endl;
		int v = ui.playPos->maximum() * pos;
		ui.playPos->setValue(v);
	}
}

stay xplay Add a timer to the constructor of

Xplay2::Xplay2(QWidget *parent)
    : QWidget(parent)
{
    
    ui.setupUi(this);
    dt.start();
	startTimer(40);
}

Synchronize control refresh with video （fps=25）