passing QVector of QPoints to a widget's paintEvent

[vonCZ]

I have an array of data in the main part of my application. I want to use these values to paint a subclassed widget. I've set it up like so:

// mainApp.cpp
 
  QVector<QPoint> points(4000);
 
  for(int a=0; a<4000; a++)
  {
    points[a].setX(   getX_from_elsewhere()  );
    points[a].setY(   getY_from_elsewhere()  );
  }
 
  ptrSubclassedWidget->draw(points);

// mainApp.cpp

  QVector<QPoint> points(4000);

  for(int a=0; a<4000; a++)
  {
    points[a].setX(   getX_from_elsewhere()  );
    points[a].setY(   getY_from_elsewhere()  );
  }

  ptrSubclassedWidget->draw(points);

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//  subClassedWidget.h
 
  private:
    QVector<QPoint>  wellData;
 
  public:
    void draw( QVector<QPoint>  dataIn);
 
  protected:
    void paintEvent(QPaintEvent *pe);

//  subClassedWidget.h

  private:
    QVector<QPoint>  wellData;

  public:
    void draw( QVector<QPoint>  dataIn);

  protected:
    void paintEvent(QPaintEvent *pe);

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//  subClassedWidget.cpp
 
  void subClassedWidget::draw(QVector<QPoint>  dataIn);
  {
    wellData = dataIn;
    update();
  }
 
  void subClassedWidget::paintEvent(QPaintEvent *pe)
  {
    //  doesn't work for obvious reason:  wellData not an *array* of QPoints, but a Vector of QPoints
    painter.drawPolyline(wellData, 4000);
  }

//  subClassedWidget.cpp

  void subClassedWidget::draw(QVector<QPoint>  dataIn);
  {
    wellData = dataIn;
    update();
  }

  void subClassedWidget::paintEvent(QPaintEvent *pe)
  {
    //  doesn't work for obvious reason:  wellData not an *array* of QPoints, but a Vector of QPoints
    painter.drawPolyline(wellData, 4000);
  }

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So, questions:

1. I know how to draw a polyLine based on an *array* of QPoint. How can I do this using a Vector of QPoints?
2. Should I be passing the QVector to draw() by reference?

[zaghaghi]

Hi,
you can use data member of QVector to retrieve its data as an array.

painter.drawPolyline(wellData.data(), 4000);

painter.drawPolyline(wellData.data(), 4000);

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[vonCZ]

Thank you! One other thing: I had to replace "4000" with wellData.size():

painter.drawPolyline(wellData.data(), wellData.size());

painter.drawPolyline(wellData.data(), wellData.size());

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