CODEWITHSUNDEEP
qt
user12800116
user12800116

Reputation:

add negative values to the progress bar

I have a realtime value from a sensor:

 ui->progressBar_retraction->setValue(aX*100); //aX is realtime value that can take positive or negative values over time

In the above expression, the progress bar shown the instantaneous positive values of aX.

How do I show negative values in a different progress bar ?

Upvotes: 0

Views: 636

Answers (1)

Erel
Erel

Reputation: 739

◘ Well, if you want to use another QProgressBar, you obviously need another one. Then simply check the sign of aX and update one of the two accordingly :

if(aX < 0){

     progress_bar_neg->setValue(qAbs(aX)*100);
     progress_bar_pos->setValue(0);

}else{

     progress_bar_pos->setValue(aX*100);
     progress_bar_neg->setValue(0);

}

Note that if you want one of your QProgressbar to fill from right to left, you can use void setInvertedAppearance(bool invert) to set its invertedAppearance to true.

◘ Another alternative using the same QProgressBar could look like :

 ui->progressBar_retraction->setValue(qAbs(aX)*100);
 if(aX < 0){/*Set to a colour*/}
 else{/*Set to another colour*}

To edit the colour :

QPalette p;
p.setColor(QPalette::Highlight, Qt::red); //Change background colour, here red
ui->progressBar_retraction->setPalette(p);
p.setColor(QPalette::HighlightedText , Qt::black); //Change text colour, here black
ui->progressBar_retraction->setPalette(p);

◘ If you want a bi-directional QProgessBar, it is unfortunately not possible by only calling a method as far as I know (correct me if I am wrong).

What I did was an override of void QProgressBar::paintEvent(QPaintEvent *) to start the drawing of the rectangle from the middle. You then simply fix the range of the QProgressBar with void QProgressBar::setRange(int minimum, int maximum). You may even update the colour to make it a bit simpler to see.

Upvotes: 1

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