progressbar level indicator

[viniltc]

Hi All,

I've progress bar to display the instantaneous value of real-time sensor.

the range for the QProgressBar is set as

ui->progressBar->setRange(0, 0.5*100); // to make range integer

ui->progressBar->setValue(sensor_read*100);

It is working ok.
Now I need to set a "threshold" value using a doubleSpinBox , as shown below:

The position of the dotted line (which is a QLabel) is the threshold that can be set using a doubleSpinBox.

My requirement is to change the height of the dotted line with respect to the threshold value.

the top and bottom y coordinates of the QProgressBar is 250 and 450

How do I get proportional y coordinate for the QLabel (dotted line) when I set a threshold value using doubleSpinBox?

[JonB]

@viniltc
Basic math? 250 + (450 - 250) * percentage? top + height * percentage? Or pretty similar?

[J.Hilk]

@viniltc the easiest way is probably to place a Vertical Layout onto of your progress bar and then manipulate the stretch values according to the spin box value

like in this example:

int main (int argc, char *argv[])
{
    QApplication a(argc, argv);


    QWidget w;
    w.resize (200, 400);
    QHBoxLayout *hLay(new QHBoxLayout(&w));

    QProgressBar pBar;
    pBar.setOrientation(Qt::Vertical);
    pBar.setMinimumWidth(50);
    QSpinBox sBox;
    sBox.setRange(0,100);
    hLay->addWidget(&pBar);
    hLay->addWidget(&sBox);

    QVBoxLayout *vLay(new QVBoxLayout(&pBar));
    vLay->addSpacerItem(new QSpacerItem(0,0, QSizePolicy::Expanding, QSizePolicy::Expanding));
    vLay->addWidget(new QLabel ("________"));
    vLay->addSpacerItem(new QSpacerItem(0,0, QSizePolicy::Expanding, QSizePolicy::Expanding));

    QObject::connect(&sBox, QOverload<int>::of(&QSpinBox::valueChanged), &pBar, [vLay](int value)->void{
        vLay->setStretch(0, 100 - value);
        vLay->setStretch(1,1);
        vLay->setStretch(2, value);
    });

    sBox.setValue(20);

    w.show();
    return  a.exec();
}

[viniltc]

@J-Hilk and @JonB Thanks a lot for your feedback.

@JonB said in progressbar level indicator:

Basic math? 250 + (450 - 250) * percentage? top + height * percentage? Or pretty similar?

Could you explain what you mean by percentage here?

I 'm trying to do something like this (changing the y coordinate of label):

 double value = 450-(ui->doubleSpinBox->value()*100); // where 450 is the bottom of progress bar, here value is not proportional to the progressbar limit
 ui->label->setGeometry(140,value,81,16);

But I'm a bit stuck to find a range for value also to make sure it chnage in proporation to the QProgressbar. Any suggestions?

[JonB]

@viniltc
You have some minimum value for the bar, say lo. You have some maximum value, say hi. And a value, say value. Doesn't matter whether those are integers, floats or whatever. So by "percentage" (actually fraction) I mean:

(value - lo) / (hi - lo)

You want your y coordinate to be miny + (maxy - miny) * percentage.