qslider sliderReleased value - c++

Question

I m trying to make a media player . The time status of the track is shown using QSlider. Track seek should happen when the user releases the slider somewhere on the QSlider. I had a look on the list of QSlider signals. The one that seems to fit is sliderReleased() which happens when the user releases the slider, but it does not get the latest value of where slider is. So to get sliders latest value I used sliderMoved() and stored reference.
Signal and slot connection
connect(this->ui->songProgress, SIGNAL(sliderMoved(int)), this,
SLOT(searchSliderMoved(int)));
connect(this->ui->songProgress, SIGNAL(sliderReleased()), this,
SLOT(searchSliderReleased()));
Functions
void MainWindow::searchSliderMoved(int search_percent)
{
value=this->ui->songProgress->value();
std::cout<<"Moved: Slider value"<<value<<std::endl;
}
Now I am Using the "value" variable inside searchSliderReleased for seeking
void MainWindow::searchSliderReleased()
{
std::cout<<"Released: Slider value"<<value<<std::endl;
emit search(value);//seek the track to location value
}
But the problem with above technique is that sliderMoved signal does not give the value where the slider is dropped but it give the location from where the slider was moved. How do I obtain the value where the slider was dropped?

Answer 1

You can use the valueChanged(int) signal of the slider, but set the flag
ui->horizontalSlider->setTracking(false);

Answer 2

Just finished building a DiectShow media player with QSlider here at work. Here's a few slot snippets on how I did it.
Widget::sliderPressed()
{
if( isPlaying() )
{
m_wasPlaying = true;
pause();
}
else
{
m_wasPlaying = false;
}
// Set a flag to denote slider drag is starting.
m_isSliderPressed = true;
}
Widget::sliderReleased()
{
if( m_wasPlaying )
{
play();
}
m_wasPlaying = false;
m_isSliderPressed = false;
}
Widget::valueChanged( int value )
{
if( m_isSliderPressed )
{
// Do seeking code here
}
else
{
// Sometime Qt when the user clicks the slider
// (no drag, just a click) Qt will signals
// pressed, released, valueChanged.
// So lets handle that here.
}
}

Answer 3

Had the same problem and calling sliderPosition() instead of value() directly when handling sliderReleased() worked for me.

Answer 4

I prefer to save the last value set by our app, like this pseudocode:
// Save our last value
lastSoftwareVal = 0;
// Set value from program
slider_set_value(value){
lastSoftwareVal = value;
slider.setValue(value)
}
// Slider on change callback
slider_on_change(value){
if(value == lastSoftwareVal){
// Value was changed by our app
return false;
}
// User has changed the value, do something
}