C++ Static function and dynamic memory

maximus

Hi,

I am building a QTableView with a list of <Workout>
Here an example :
https://www.dropbox.com/s/fr9pfy4a8mgbuqt/workoutList1.png

To draw the graph, I had to reimplement paint in a custom Delegate.
#1 down here is the current code that does that (working fine)

What I want to do, is do the graphing stuff in another class with a static method so I can use it from other places.
So I made the class "util.h" with this method :
static std::shared_ptr<QwtPlot> plotWorkout(std::shared_ptr<Workout> workout);
see #2 for code, it is the exact same code as #1, but it seems my histogram data is not transfering. I suspect it has to do with QVector object been deleted as soon as I exit my static function? How can I create a QVector dynamicly so that it doesn't get deleted? I'm new with C++ and the syntax is a bit daunting for me. Usually what I do is to keep a pointer of a "new" object but QVector doesn't support "new"

Thanks in advance !!

#1
@void MyDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
std::shared_ptr<QwtPlot> plot(new QwtPlot());

// ---- GRAPH -------------------------
plot->setCanvasBackground(QColor(Qt::black));
plot->setAxisScale( QwtPlot::yLeft, 0.0, 100);
plot->setAxisScale( QwtPlot::xBottom, 0.0, workout->getTotalLength());
plot->enableAxis(0, false);
plot->enableAxis(2, false);


// ---- HISTOGRAM (POWER INTERVAL) -----
std::shared_ptr<QwtPlotHistogram> histo(new QwtPlotHistogram());
histo->setZ(0);
histo->setStyle(QwtPlotHistogram::Columns);
histo->setPen( QPen( Qt::darkGreen, 1 ) );
histo->setBrush( QBrush(Qt::darkGreen) );

// ----- INTERVAL dans HISTOGRAM --------
QVector<QwtIntervalSample> samples(workout->getNbInterval());
double time = 0;
int i = 0;
foreach (std::shared_ptr<Interval> val, workout->getLstInterval()) {
    QwtInterval interval(time, time + val->getLength());
    qDebug() << "FTP T: " << val->getTargentFTP();
    samples[i]= QwtIntervalSample(val->getTargentFTP(), interval);
    time += val->getLength();
    i++;
}

histo->setData(new QwtIntervalSeriesData(samples));
histo->attach(plot.get());
plot->replot();




if (option.state & QStyle::State_Selected)
    painter->fillRect(option.rect, option.palette.highlight());


QwtPlotRenderer* plotRender = new QwtPlotRenderer();
plotRender->setDiscardFlag(QwtPlotRenderer::DiscardBackground, true);
plotRender->setDiscardFlag(QwtPlotRenderer::DiscardCanvasBackground, true);
plotRender->setDiscardFlag(QwtPlotRenderer::DiscardLegend,true);
plotRender->setDiscardFlag(QwtPlotRenderer::DiscardTitle,true);
plotRender->setDiscardFlag(QwtPlotRenderer::DiscardFooter,true);
plotRender->setLayoutFlag(QwtPlotRenderer::FrameWithScales,true);



plotRender->render(plot.get(), painter, option.rect);

}@

#2
@//--------------------------------------------------------------------------
std::shared_ptr<QwtPlot> Util::plotWorkout(std::shared_ptr<Workout> workout) {

std::shared_ptr<QwtPlot> plot(new QwtPlot());


// ---- GRAPH -------------------------
plot->setCanvasBackground(QColor(Qt::black));
plot->setAxisScale( QwtPlot::yLeft, 0.0, 100);
plot->setAxisScale( QwtPlot::xBottom, 0.0, workout->getTotalLength());

// plot->enableAxis(0, false);
// plot->enableAxis(2, false);

// ---- HISTOGRAM (POWER INTERVAL) -----
std::shared_ptr<QwtPlotHistogram> histo(new QwtPlotHistogram());

histo->setZ(0);
histo->setStyle(QwtPlotHistogram::Columns);
histo->setPen( QPen( Qt::darkGreen, 1 ) );
histo->setBrush( QBrush(Qt::darkGreen) );

// ----- INTERVAL dans HISTOGRAM --------
QVector<QwtIntervalSample> samples(workout->getNbInterval());
double time = 0;
int i = 0;
foreach (std::shared_ptr<Interval> val, workout->getLstInterval()) {
    QwtInterval interval(time, time + val->getLength());
    samples[i]= QwtIntervalSample(val->getTargentFTP(), interval);
    time += val->getLength();
    i++;
}


histo->setData(new QwtIntervalSeriesData(samples));
histo->attach(plot.get());
plot->replot();
return plot;

}@