QwtPointMapper - A helper class for translating a series of points.

NAME SYNOPSIS Public Types Public Member Functions Detailed Description Member Typedef Documentation typedef QFlags<TransformationFlag > QwtPointMapper::TransformationFlags Member Enumeration Documentation enum QwtPointMapper::TransformationFlag Constructor & Destructor Documentation QwtPointMapper::QwtPointMapper () QwtPointMapper::˜QwtPointMapper () Member Function Documentation QRectF QwtPointMapper::boundingRect () const QwtPointMapper::TransformationFlags QwtPointMapper::flags () const void QwtPointMapper::setBoundingRect (const QRectF & rect) void QwtPointMapper::setFlag (TransformationFlag flag, bool on = true) void QwtPointMapper::setFlags (TransformationFlags flags) bool QwtPointMapper::testFlag (TransformationFlag flag) const QImage QwtPointMapper::toImage (const QwtScaleMap & xMap, const QwtScaleMap& yMap, const QwtSeriesData< QPointF > * series, int from, int to,const QPen & pen, bool antialiased, uint numThreads) const QPolygon QwtPointMapper::toPoints (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const QPolygonF QwtPointMapper::toPointsF (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const QPolygon QwtPointMapper::toPolygon (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const QPolygonF QwtPointMapper::toPolygonF (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const Author

NAME

QwtPointMapper − A helper class for translating a series of points.

enum TransformationFlag { RoundPoints = 0x01, WeedOutPoints = 0x02, WeedOutIntermediatePoints = 0x04 }
Flags affecting the transformation process.
typedef QFlags< TransformationFlag > TransformationFlags

Public Member Functions

QwtPointMapper ()
Constructor.
˜QwtPointMapper ()
Destructor.
void setFlags (TransformationFlags)
TransformationFlags flags () const
void setFlag (TransformationFlag, bool on=true)
bool testFlag (TransformationFlag) const
void setBoundingRect (const QRectF &)
QRectF boundingRect () const
QPolygonF toPolygonF (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtSeriesData< QPointF > *series, int from, int to) const
Translate a series of points into a QPolygonF.
QPolygon toPolygon (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtSeriesData< QPointF > *series, int from, int to) const
Translate a series of points into a QPolygon.
QPolygon toPoints (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtSeriesData< QPointF > *series, int from, int to) const
Translate a series of points into a QPolygon.
QPolygonF toPointsF (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtSeriesData< QPointF > *series, int from, int to) const
Translate a series into a QPolygonF.
QImage toImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtSeriesData< QPointF > *series, int from, int to, const QPen &, bool antialiased, uint numThreads) const
Translate a series into a QImage.

Detailed Description

A helper class for translating a series of points.

QwtPointMapper is a collection of methods and optimizations for translating a series of points into paint device coordinates. It is used by QwtPlotCurve but might also be useful for similar plot items displaying a QwtSeriesData<QPointF>.

Definition at line 32 of file qwt_point_mapper.h.

Member Typedef Documentation

typedef QFlags<TransformationFlag > QwtPointMapper::TransformationFlags

An ORed combination of TransformationFlag values.

Definition at line 71 of file qwt_point_mapper.h.

Member Enumeration Documentation

enum QwtPointMapper::TransformationFlag

Flags affecting the transformation process.

See also

setFlag(), setFlags()

Enumerator
RoundPoints

Round points to integer values.

WeedOutPoints

Try to remove points, that are translated to the same position.

WeedOutIntermediatePoints

An even more aggressive weeding algorithm, that can be used in toPolygon().

A consecutive chunk of points being mapped to the same x coordinate is reduced to 4 points:

	•		first point
	•		point with the minimum y coordinate
	•		point with the maximum y coordinate
	•		last point

In the worst case ( first and last points are never one of the extremes ) the number of points will be 4 times the width.

As the algorithm is fast it can be used inside of a polyline render cycle.

Definition at line 39 of file qwt_point_mapper.h.

Constructor & Destructor Documentation

QwtPointMapper::QwtPointMapper ()

Constructor.

Definition at line 547 of file qwt_point_mapper.cpp.

QwtPointMapper::˜QwtPointMapper ()

Destructor.

Definition at line 553 of file qwt_point_mapper.cpp.

Member Function Documentation

QRectF QwtPointMapper::boundingRect () const

Returns

Bounding rectangle

See also

setBoundingRect()

Definition at line 621 of file qwt_point_mapper.cpp.

QwtPointMapper::TransformationFlags QwtPointMapper::flags () const

Returns

Flags affecting the transformation process

See also

setFlags(), setFlag()

Definition at line 573 of file qwt_point_mapper.cpp.

void QwtPointMapper::setBoundingRect (const QRectF & rect)

Set a bounding rectangle for the point mapping algorithm

A valid bounding rectangle can be used for optimizations

Parameters

rect Bounding rectangle

See also

boundingRect()

Definition at line 612 of file qwt_point_mapper.cpp.

void QwtPointMapper::setFlag (TransformationFlag flag, bool on = true)

Modify a flag affecting the transformation process

Parameters

flag Flag type
on Value

See also

flag(), setFlags()

Definition at line 586 of file qwt_point_mapper.cpp.

void QwtPointMapper::setFlags (TransformationFlags flags)

Set the flags affecting the transformation process

Parameters

flags Flags

See also

flags(), setFlag()

Definition at line 564 of file qwt_point_mapper.cpp.

bool QwtPointMapper::testFlag (TransformationFlag flag) const

Returns

True, when the flag is set

Parameters

flag Flag type

See also

setFlag(), setFlags()

Definition at line 599 of file qwt_point_mapper.cpp.

QImage QwtPointMapper::toImage (const QwtScaleMap & xMap, const QwtScaleMap& yMap, const QwtSeriesData< QPointF > * series, int from, int to,const QPen & pen, bool antialiased, uint numThreads) const

Translate a series into a QImage.

Parameters

xMap x map
yMap y map
series Series of points to be mapped
from Index of the first point to be painted
to Index of the last point to be painted
pen Pen used for drawing a point of the image, where a point is mapped to
antialiased True, when the dots should be displayed antialiased
numThreads Number of threads to be used for rendering. If numThreads is set to 0, the system specific ideal thread count is used.

Returns

Image displaying the series

Definition at line 883 of file qwt_point_mapper.cpp.

QPolygon QwtPointMapper::toPoints (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const

Translate a series of points into a QPolygon.

	•		WeedOutPoints & boundingRect().isValid() All points that are mapped to the same position will be one point. Points outside of the bounding rectangle are ignored.
	•		WeedOutPoints & !boundingRect().isValid() All consecutive points that are mapped to the same position will one point
	•		!WeedOutPoints & boundingRect().isValid() Points outside of the bounding rectangle are ignored.

Parameters

xMap x map
yMap y map
series Series of points to be mapped
from Index of the first point to be painted
to Index of the last point to be painted

Returns

Translated polygon

Definition at line 833 of file qwt_point_mapper.cpp.

QPolygonF QwtPointMapper::toPointsF (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const

Translate a series into a QPolygonF.

	•		WeedOutPoints & RoundPoints & boundingRect().isValid() All points that are mapped to the same position will be one point. Points outside of the bounding rectangle are ignored.
	•		WeedOutPoints & RoundPoints & !boundingRect().isValid() All consecutive points that are mapped to the same position will one point
	•		WeedOutPoints & !RoundPoints All consecutive points that are mapped to the same position will one point
	•		!WeedOutPoints & boundingRect().isValid() Points outside of the bounding rectangle are ignored.

When RoundPoints is set all points are rounded to integers but returned as PolygonF - what only makes sense when the further processing of the values need a QPolygonF.

Parameters

xMap x map
yMap y map
series Series of points to be mapped
from Index of the first point to be painted
to Index of the last point to be painted

Returns

Translated polygon

Definition at line 759 of file qwt_point_mapper.cpp.

QPolygon QwtPointMapper::toPolygon (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const

Translate a series of points into a QPolygon. When the WeedOutPoints flag is enabled consecutive points, that are mapped to the same position will be one point.

Parameters

xMap x map
yMap y map
series Series of points to be mapped
from Index of the first point to be painted
to Index of the last point to be painted

Returns

Translated polygon

Definition at line 702 of file qwt_point_mapper.cpp.

QPolygonF QwtPointMapper::toPolygonF (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QwtSeriesData< QPointF > * series, int from,int to) const

Translate a series of points into a QPolygonF. When the WeedOutPoints flag is enabled consecutive points, that are mapped to the same position will be one point.

When RoundPoints is set all points are rounded to integers but returned as PolygonF - what only makes sense when the further processing of the values need a QPolygonF.

When RoundPoints & WeedOutIntermediatePoints is enabled an even more aggressive weeding algorithm is enabled.

Parameters

xMap x map
yMap y map
series Series of points to be mapped
from Index of the first point to be painted
to Index of the last point to be painted

Returns

Translated polygon

Definition at line 647 of file qwt_point_mapper.cpp.

Author

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Updated 2026-06-01 - jenkler.se | uex.se