Detecting QCandlestickSet in a QList<QGraphicsItem *>

MiC78

Hi everyone,

I am really having troubles to detect the QCandelstickSet elements after calling the next sentence:
itemList = scene->items(rect, Qt::IntersectsItemShape, Qt::DescendingOrder);

Of course, the QCandlestickSet elements are drawn in a Qchart in a QChartView, which has its corresponding scene.

I tried the following but did not work:

for (int i = 0; i < itemList.count(); ++i)
  {
    QCandlestickSet *set = dynamic_cast<QCandlestickSet*>(itemList.at(i));
    if(set)
    {
     ...
    }
  }

I was reading the Qt documentation but I think I am missing something. It says that it must be through the const int QGraphicsItem::UserType
The lowest permitted type value for custom items (subclasses of QGraphicsItem or any of the standard items). This value is used in conjunction with a reimplementation of QGraphicsItem::type() and declaring a Type enum value. Example:

  class CustomItem : public QGraphicsItem
  {
  public:
     enum { Type = UserType + 1 };

     int type() const
     {
         // Enable the use of qgraphicsitem_cast with this item.
         return Type;
     }
     ...
  };

Does that mean that I have to create my own QCandlestickSet class derived from QGraphicsItem?

If someone knows how to do it, I would really appreciate an example.

Thank you.

VRonin

QCandlestickSet does not inherit QGraphicsItem so there's no way your cast can have success.

The cast could work with CandlestickChartItem but it's a private class: https://code.woboq.org/qt5/qtcharts/src/charts/candlestickchart/candlestickchartitem_p.h.html

Andeol

Does that mean that I have to create my own QCandlestickSet class derived from QGraphicsItem?

I think so. Not sure, since I don't really understand what you are trying to do. scene->items() will give you a list of items. Nothing else is going to be in this list.

This is the first time I hear about candleStickSet, so I'm not sure, but can't you do something like this?

class myCandleStickItem: public QGraphicsItem{
public:
myCandleStickItem(QWidget *parent = Q_NULLPTR) ;
QCandlestickSet getcandlestickSet() {return candlestickSet ;}
void setCandleStickSet( QCandlestickSet newone) { candlestickSet  = newone ;}

private: 
QCandlestickSet candlestickSet;
}

MiC78

@Andeol
Hi,
Maybe I should have started saying that I have a QCandlestickSeries *series where I store financial data. Each single day in the series is stored in its corresponding QCandelstickSets *set. The series is added to a QChart chart and this one presented in a QChartView view.

So far everything works since the date is drawn when I press the button. I even reimplemented the QChartView class to have my own zoom command. And that works also. This is the part of the reimplemented class with respect to the zoom:

void ChartView::keyPressEvent(QKeyEvent *event)
{
QRectF rect = chart()->plotArea();
qreal adjustment = rect.width() / 2;

switch (event->key())
{
case Qt::Key_Up:
{

    //rect.setX(chart()->plotArea().x() + adjustment);
    rect.adjust(adjustment, 0, 0, 0);
    chart()->zoomIn(rect);
  }
  break;

case Qt::Key_Down:
.
.
.

As you can see, the zoom is only in the X axis.
I would like to zoom the Y axis as well, but in such a way that it takes into account the maximum value of the different sets (QCandlestickSet) that fall inside the x-zoomed area. That is to say, I would like an autoscale in the Y axis to watch the sets as big as possible.

To do that, I was thinking on something like:

QGraphicsScene *scene = chart()->scene();
QList<QGraphicsItem *> itemList;
itemList = scene->items(rect, Qt::IntersectsItemShape, Qt::DescendingOrder);

But this is not working, as you guys said before.

Thank you very much for your help,