Getting QTimeLine and QProgressBar to work

  • I am trying to get a timeline and a progress bar to work. The relevant code snippet is as follows:

    void dlg_player::play() /// Slot from button clicked signal

    void dlg_player::start()
    ui->progressBar->setRange(0,100); /// ui from Qt designer.
    QTimeLine *timeLine = new QTimeLine(mSecs, this);
    timeLine->setFrameRange(0, 100);
    connect(timeLine, SIGNAL(frameChanged(int)),
    ui->progressBar,SLOT(setValue(int))); /// ui from Qt designer
    timeLine->start(); /// Is this required?

    void dlg_player::calcLen(QString plLen) /// Calculates m Secs from a "(mm:ss)" string
    if(plLen.contains('(')) plLen.remove('(');
    if(plLen.contains(')')) plLen.remove(')');
    playLen = plLen;
    mSecs = HMStoSecs(playlLen) * 1000;

    It compiles and the debugger shows all variables as correct. The program starts OK but the progress bar does nothing.

    Any help or advice would be greatly appreciated.
    Thank you.

  • Qt Champions 2017

    what is the start value of progress bar ? Definitely start is required.

    try setting bar->setValue(0)

  • Thank you for your prompt reply.
    I tried ui->progressBar->setValue(0); in my code.
    (It was already set to zero in designer properties, so was the max and min values)
    It did not work.
    Thank you again

  • Lifetime Qt Champion


    What is mSecs value ?

  • Hi
    mSecs is a qint32 and can of course be set to anything from, lets say, zero to one hour in milliseconds = 0 to 3600000 (Unlikely to be this much).
    My test code is 8 min 30 sec = 510000 mSecs.
    Thanks again

  • Qt Champions 2017

    Wild thought. Can check whether your start method is called first ? Issue may exist there only. Can you put some debug statement and check inside the start method.

    I made this sample. See how this works.

    @Widget::Widget(QWidget *parent)
    : QWidget(parent)
    QProgressBar *bar = new QProgressBar(this);
    QTimeLine *tim = new QTimeLine(5000,this);


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