QLineSeries OpenGL issue



  • Hello Everybody,

    I've been playing around with QtCharts. Thought I would convert one of my application which uses qwt to QtCharts. Unfortunatelly I'm running into some issues.

    I'm not able to generate a line chart with large X values when setUseOpenGL is enabled.

    Here is a code which doesn't render anything.

    QLineSeries *series = new QLineSeries();
    
        series->append(1490215139925, 0.841470985);
        series->append(1490215157925, 0.14987721);
        series->append(1490215158925, 0.912945251);
        series->append(1490215159925, 0.836655639);
        series->append(1490215160925, -0.008851309);
    
        series->setUseOpenGL(true);
    
    
        chart = new QChart();
        chart->setTitle( ui->titleEdit->text() );
        QFont tFont = chart->titleFont();
        tFont.setPointSizeF( 15 );
        tFont.setBold( true );
        chart->setTitleFont( tFont );
    
    
        axisX = new QValueAxis;
        axisX->setRange( (qreal)1490215139925, (qreal)1490215163925 );
        axisX->setTickCount(10);
        axisX->setLabelFormat("%l");
        axisX->setTitleText("unixTime");
    
        axisY = new QValueAxis;
        axisY->setRange(-1, 1);
        axisY->setTitleText("Level");
        chart->setAxisX(dateAxisX);
        chart->setAxisY(axisY);
    
        chart->addSeries(series);
        series->attachAxis(axisX);
        series->attachAxis(axisY);
    

    As I mentioned before change setUseOpenGL to false

      series->setUseOpenGL(false);
    

    And all works fine.

    Couple other things I tried or noticed:

    • If x values are in 32 bit range it seems to work fine in opengl mode
    • Tried changing QValueAxis to QDateTimeAxis still doesn't work in opengl mode

    Any ideas is it a bug? Is there a workaround? Is this a limitation of OpenGL not able to take in large numbers?

    I'm using Qt 5.8 with MinGW 5.3.0 32bit


  • Lifetime Qt Champion

    Hi,

    I'd go check the bug report system to see if there's something related.



  • Thanks for your reply, it seems there is no bug reported regarding this issue. Only similar one is that QLineSeries can't be hidden when openGL is enabled.

    I'll write an example test code and submit a bug


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