Accessing member variables of QwtPlotCurve from within the

[alainstgt]

Accessing member variables (minXValue, minYValue...) of QwtPlotCurve from within the parent class
Qwt 6.0.1, Qt 4.8.4

Hello everyone!

I have realized my own plot class derived from QwtPlot.
I have defined a method setMarkerOnMax() which needs as parameters among others a pointer to the data and the data size. But those are already known by the plot object, so I find it boring to have to reinter that information.
Within the method attachCurve() I can successfuly access those variables, but I did´nt succeed in accessing them from within the parent class. I took a look to Qwt_plot_item and Qwt_plot_dict but have no idea how to proceed.

I have attached some code snippets.

Any idea?

Thanks for reading.

Alain

// Usage
Plot2D* pLogSpectrum = new Plot2D( "Spectrum", "frequency", "magnitude [dB]", Qt::darkBlue, app );
pLogSpectrum->attachCurve( pXData, pLogMag, HALF_LENGTH, "noisy sine", Qt::cyan );
pLogSpectrum->setMarkerOnMax( pXData, pLogMag, HALF_LENGTH, -3 );

// Usage
Plot2D* pLogSpectrum = new Plot2D( "Spectrum", "frequency", "magnitude [dB]", Qt::darkBlue, app );
pLogSpectrum->attachCurve( pXData, pLogMag, HALF_LENGTH, "noisy sine", Qt::cyan );
pLogSpectrum->setMarkerOnMax( pXData, pLogMag, HALF_LENGTH, -3 );

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I would prefer:

pLogSpectrum->setMarkerOnMax( -3 );

pLogSpectrum->setMarkerOnMax( -3 );

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//  Declaration
class Plot2D: public QwtPlot
{
  Q_OBJECT
 
public:
  Plot2D( QString plotTitle = "Data Plot",			
          QString xLabel = "x-axis",
          QString yLabel = "y-axis",
          QColor backgoundColor = Qt::darkGray,
          QWidget *parent = NULL ); 
 
  void attachCurve( double* xData,
                    double *yData,
                    int dataCount, 
                    QString curveLabel = "",
                    QColor lineColor = Qt::yellow );
 
  void setMarkerOnMax( SLData_t* xData,
                       SLData_t* yData,
                       SLArrayIndex_t dataCount,
                       int precision = 4,	  // positive value for '%.*g', negative value for '%.*f'
                       Qt::Alignment alignment = Qt::AlignHCenter | Qt::AlignTop );
 
  void setMarker( double X, 
                  double Y, 
                  int precision = 4,  // positive value for '%.*g', negative value for '%.*f'
                  Qt::Alignment alignment = Qt::AlignHCenter | Qt::AlignTop );
 
  ...
 
public Q_SLOTS:
  void autoRescale( QRectF );
  void printDocument();
  void exportDocument();
 
protected:
  virtual void resizeEvent( QResizeEvent * );
 
private:
  int mWindowHeight, mWindowWidth;
  int mWindowXPosition, mWindowYPosition;
  QwtPlotGrid* grid;
  QwtLegend* legend;
  QwtPlotZoomer* zoomer;
  QPushButton* btnPrint;
  QPushButton* btnExport;
};

//  Declaration
class Plot2D: public QwtPlot
{
  Q_OBJECT

public:
  Plot2D( QString plotTitle = "Data Plot",			
          QString xLabel = "x-axis",
          QString yLabel = "y-axis",
          QColor backgoundColor = Qt::darkGray,
          QWidget *parent = NULL ); 

  void attachCurve( double* xData,
                    double *yData,
                    int dataCount, 
                    QString curveLabel = "",
                    QColor lineColor = Qt::yellow );

  void setMarkerOnMax( SLData_t* xData,
                       SLData_t* yData,
                       SLArrayIndex_t dataCount,
                       int precision = 4,	  // positive value for '%.*g', negative value for '%.*f'
                       Qt::Alignment alignment = Qt::AlignHCenter | Qt::AlignTop );

  void setMarker( double X, 
                  double Y, 
                  int precision = 4,  // positive value for '%.*g', negative value for '%.*f'
                  Qt::Alignment alignment = Qt::AlignHCenter | Qt::AlignTop );
	
  ...

public Q_SLOTS:
  void autoRescale( QRectF );
  void printDocument();
  void exportDocument();

protected:
  virtual void resizeEvent( QResizeEvent * );

private:
  int mWindowHeight, mWindowWidth;
  int mWindowXPosition, mWindowYPosition;
  QwtPlotGrid* grid;
  QwtLegend* legend;
  QwtPlotZoomer* zoomer;
  QPushButton* btnPrint;
  QPushButton* btnExport;
};

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// implementation
Plot2D::Plot2D( QString plotTitle,
                QString xLabel,
                QString yLabel,
                QColor backgroundColor,
                QWidget *parent ): 
                QwtPlot( parent )
{
  // plot object
  setWindowTitle ( QString( "SigLibGraph - Plot2D" ));
  setTitle( plotTitle );
  setCanvasBackground( backgroundColor);
 
  // window size and position
  setMinimumSize( QSize( 240, 170 ));
  mWindowWidth = 550; mWindowHeight = 365;
  mWindowXPosition = 200; mWindowYPosition = 200;
  setGeometry( mWindowXPosition, mWindowYPosition, mWindowWidth, mWindowHeight );
 
  // axis
  setAxisTitle( QwtPlot::xBottom, xLabel );
  setAxisTitle( QwtPlot::yLeft, yLabel );
 
  // grid 
  grid = new QwtPlotGrid;
  grid->enableXMin( true );
  grid->setMajPen( QPen( Qt::white, 0, Qt::DotLine ));
  grid->setMinPen( QPen( Qt::gray, 0 , Qt::DotLine ));
  grid->attach( this );
 
  // legend
  legend = new QwtLegend;
  insertLegend( legend, QwtPlot::RightLegend );
 
  //zoomer
  ...
 
  // print functionality
  btnPrint = new QPushButton( "&Print", this );
  ...
 
  // export functionality
  btnExport = new QPushButton( "&Export", this );
  ...
 
  show();
}
 
void Plot2D::attachCurve( SLData_t* xData,
                          SLData_t* yData,
                          int dataCount, 
                          QString curveLabel,
                          QColor lineColor )
{
  QwtPlotCurve* curve = new QwtPlotCurve;
 
  curve->setSamples( xData, yData, dataCount );
  // following works well
  //qDebug() << "xMin=" << curve->minXValue() << " | xMax=" << curve->maxXValue()
  //         << " | yMin=" << curve->minYValue() << " | yMax=" << curve->maxYValue() 
  //         << " | data count=" << curve->dataSize();
 
  QPen curvePen;
  curvePen.setColor( lineColor );
  curve->setPen( curvePen );
 
  curve->setRenderHint( QwtPlotItem::RenderAntialiased );
 
  curve->setTitle( curveLabel );
 
  if ( curveLabel.isEmpty() )
    curve->setItemAttribute( QwtPlotItem::Legend, false );
  else 
    curve->setLegendAttribute( QwtPlotCurve::LegendShowLine );	
 
  curve->attach( this );
}
 
void Plot2D::setMarkerOnMax( SLData_t* xData,
                             SLData_t* yData,
                             SLArrayIndex_t dataCount,
                             int precision,  // positive value for '%.*g', negative value for '%.*f'
                             Qt::Alignment alignment )
{
  SLArrayIndex_t index = SDA_MaxPos( xData, dataCount );  // get the index of max value
  setMarker( xData[index], yData[index], precision, alignment );  // set marker position
}
 
void Plot2D::setMarker( double X, 
                        double Y, 
                        int precision,
                        Qt::Alignment alignment )
{
  QwtPlotMarker* marker = new QwtPlotMarker();
  marker->setValue( X, Y );
  marker->setSymbol( new QwtSymbol( QwtSymbol::Cross, 
                                    QColor( Qt::white ), 
                                    QColor( Qt::white ), 
                                    QSize( 10, 10 )));
  QString label;
    if (precision < 0)
      label.sprintf( "(%.*f | %.*f)", -precision, X, -precision, Y );
    else
      label.sprintf( "(%.*g | %.*g)", precision, X, precision, Y );
  QwtText text( label );
  text.setColor( QColor( Qt::white ));
  text.setFont( QFont("Helvetica", 8, QFont::Bold ));
 
  marker->setLabel( text );
  marker->setLabelAlignment( alignment );
  marker->attach( this );
}

// implementation
Plot2D::Plot2D( QString plotTitle,
                QString xLabel,
                QString yLabel,
                QColor backgroundColor,
                QWidget *parent ): 
                QwtPlot( parent )
{
  // plot object
  setWindowTitle ( QString( "SigLibGraph - Plot2D" ));
  setTitle( plotTitle );
  setCanvasBackground( backgroundColor);

  // window size and position
  setMinimumSize( QSize( 240, 170 ));
  mWindowWidth = 550; mWindowHeight = 365;
  mWindowXPosition = 200; mWindowYPosition = 200;
  setGeometry( mWindowXPosition, mWindowYPosition, mWindowWidth, mWindowHeight );

  // axis
  setAxisTitle( QwtPlot::xBottom, xLabel );
  setAxisTitle( QwtPlot::yLeft, yLabel );

  // grid 
  grid = new QwtPlotGrid;
  grid->enableXMin( true );
  grid->setMajPen( QPen( Qt::white, 0, Qt::DotLine ));
  grid->setMinPen( QPen( Qt::gray, 0 , Qt::DotLine ));
  grid->attach( this );

  // legend
  legend = new QwtLegend;
  insertLegend( legend, QwtPlot::RightLegend );

  //zoomer
  ...

  // print functionality
  btnPrint = new QPushButton( "&Print", this );
  ...
	
  // export functionality
  btnExport = new QPushButton( "&Export", this );
  ...

  show();
}

void Plot2D::attachCurve( SLData_t* xData,
                          SLData_t* yData,
                          int dataCount, 
                          QString curveLabel,
                          QColor lineColor )
{
  QwtPlotCurve* curve = new QwtPlotCurve;

  curve->setSamples( xData, yData, dataCount );
  // following works well
  //qDebug() << "xMin=" << curve->minXValue() << " | xMax=" << curve->maxXValue()
  //         << " | yMin=" << curve->minYValue() << " | yMax=" << curve->maxYValue() 
  //         << " | data count=" << curve->dataSize();

  QPen curvePen;
  curvePen.setColor( lineColor );
  curve->setPen( curvePen );

  curve->setRenderHint( QwtPlotItem::RenderAntialiased );

  curve->setTitle( curveLabel );
  
  if ( curveLabel.isEmpty() )
    curve->setItemAttribute( QwtPlotItem::Legend, false );
  else 
    curve->setLegendAttribute( QwtPlotCurve::LegendShowLine );	

  curve->attach( this );
}

void Plot2D::setMarkerOnMax( SLData_t* xData,
                             SLData_t* yData,
                             SLArrayIndex_t dataCount,
                             int precision,  // positive value for '%.*g', negative value for '%.*f'
                             Qt::Alignment alignment )
{
  SLArrayIndex_t index = SDA_MaxPos( xData, dataCount );  // get the index of max value
  setMarker( xData[index], yData[index], precision, alignment );  // set marker position
}

void Plot2D::setMarker( double X, 
                        double Y, 
                        int precision,
                        Qt::Alignment alignment )
{
  QwtPlotMarker* marker = new QwtPlotMarker();
  marker->setValue( X, Y );
  marker->setSymbol( new QwtSymbol( QwtSymbol::Cross, 
                                    QColor( Qt::white ), 
                                    QColor( Qt::white ), 
                                    QSize( 10, 10 )));
  QString label;
    if (precision < 0)
      label.sprintf( "(%.*f | %.*f)", -precision, X, -precision, Y );
    else
      label.sprintf( "(%.*g | %.*g)", precision, X, precision, Y );
  QwtText text( label );
  text.setColor( QColor( Qt::white ));
  text.setFont( QFont("Helvetica", 8, QFont::Bold ));

  marker->setLabel( text );
  marker->setLabelAlignment( alignment );
  marker->attach( this );
}

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