QwtSyntheticPointData(3) | Qwt User's Guide | QwtSyntheticPointData(3) |
NAME¶
QwtSyntheticPointData -Synthetic point data.
SYNOPSIS¶
#include <qwt_point_data.h>
Inherits QwtSeriesData< QPointF >.
Public Member Functions¶
QwtSyntheticPointData (size_t size, const QwtInterval &=QwtInterval())
void setSize (size_t size)
virtual size_t size () const
void setInterval (const QwtInterval &)
QwtInterval interval () const
virtual QRectF boundingRect () const
Calculate the bounding rectangle. virtual QPointF sample (size_t i) const
virtual double y (double x) const =0
virtual double x (uint index) const
virtual void setRectOfInterest (const QRectF &)
QRectF rectOfInterest () const
Additional Inherited Members¶
Detailed Description¶
Synthetic point data.QwtSyntheticPointData provides a fixed number of points for an interval. The points are calculated in equidistant steps in x-direction.
If the interval is invalid, the points are calculated for the 'rectangle of interest', what normally is the displayed area on the plot canvas. In this mode you get different levels of detail, when zooming in/out.
Example
The following example shows how to implement a sinus curve.
#include <cmath> #include <qwt_series_data.h> #include <qwt_plot_curve.h> #include <qwt_plot.h> #include <qapplication.h> class SinusData: public QwtSyntheticPointData { public: SinusData(): QwtSyntheticPointData( 100 ) { } virtual double y( double x ) const { return qSin( x ); } }; int main(int argc, char **argv) { QApplication a( argc, argv ); QwtPlot plot; plot.setAxisScale( QwtPlot::xBottom, 0.0, 10.0 ); plot.setAxisScale( QwtPlot::yLeft, -1.0, 1.0 ); QwtPlotCurve *curve = new QwtPlotCurve( "y = sin(x)" ); curve->setData( new SinusData() ); curve->attach( &plot ); plot.show(); return a.exec(); }
Constructor & Destructor Documentation¶
QwtSyntheticPointData::QwtSyntheticPointData (size_tsize, const QwtInterval &interval = QwtInterval())¶
ConstructorParameters:
interval Bounding interval for the points
See Also:
Member Function Documentation¶
QRectF QwtSyntheticPointData::boundingRect () const [virtual]¶
Calculate the bounding rectangle. This implementation iterates over all points, what could often be implemented much faster using the characteristics of the series. When there are many points it is recommended to overload and reimplement this method using the characteristics of the series ( if possible ).Returns:
Implements QwtSeriesData< QPointF >.
QwtInterval QwtSyntheticPointData::interval () const¶
Returns:See Also:
QRectF QwtSyntheticPointData::rectOfInterest () const¶
Returns:See Also:
QPointF QwtSyntheticPointData::sample (size_tindex) const [virtual]¶
Calculate the point from an indexParameters:
Returns:
Warning:
Implements QwtSeriesData< QPointF >.
void QwtSyntheticPointData::setInterval (const QwtInterval &interval)¶
Set the bounding intervalParameters:
See Also:
void QwtSyntheticPointData::setRectOfInterest (const QRectF &rect) [virtual]¶
Set a the 'rectangle of interest'QwtPlotSeriesItem defines the current area of the plot canvas as 'rect of interest' ( QwtPlotSeriesItem::updateScaleDiv() ).
If interval().isValid() == false the x values are calculated in the interval rect.left() -> rect.right().
See Also:
Reimplemented from QwtSeriesData< QPointF >.
void QwtSyntheticPointData::setSize (size_tsize)¶
Change the number of pointsParameters:
See Also:
size_t QwtSyntheticPointData::size () const [virtual]¶
Returns:See Also:
Implements QwtSeriesData< QPointF >.
double QwtSyntheticPointData::x (uintindex) const [virtual]¶
Calculate a x-value from an indexx values are calculated by dividing an interval into equidistant steps. If !interval().isValid() the interval is calculated from the 'rectangle of interest'.
Parameters:
Returns:
See Also:
virtual double QwtSyntheticPointData::y (doublex) const [pure virtual]¶
Calculate a y value for a x valueParameters:
Returns:
Author¶
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