Qwt User's Guide: QwtPointMapper Class Reference

Qwt User's Guide 6.2.0

Public Types | Public Member Functions | List of all members
QwtPointMapper Class Reference

A helper class for translating a series of points. More...

`#include <qwt_point_mapper.h>`

## Public Types
enum | TransformationFlag { RoundPoints = 0x01 , WeedOutPoints = 0x02 , WeedOutIntermediatePoints = 0x04 }
| Flags affecting the transformation process. More...
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. More...
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. More...
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. More...
QPolygonF | toPointsF (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtSeriesData< QPointF > *series, int from, int to) const
| Translate a series into a QPolygonF. More...
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. More...

## 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

## ◆ TransformationFlags

typedef QFlags<TransformationFlag > QwtPointMapper::TransformationFlags

An ORed combination of TransformationFlag values.

Definition at line 71 of file qwt_point_mapper.h.

## Member Enumeration Documentation

## ◆ TransformationFlag

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.

## Member Function Documentation

## ◆ boundingRect()

QRectF QwtPointMapper::boundingRect | ( |  | ) | const

Returns
  Bounding rectangle

See also
  setBoundingRect()

Definition at line 621 of file qwt_point_mapper.cpp.

## ◆ flags()

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.

## ◆ setBoundingRect()

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.

## ◆ setFlag()

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.

## ◆ setFlags()

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.

## ◆ testFlag()

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.

## ◆ toImage()

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.

## ◆ toPoints()

QPolygon QwtPointMapper::toPoints | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | 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.

## ◆ toPointsF()

QPolygonF QwtPointMapper::toPointsF | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | 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.

## ◆ toPolygon()

QPolygon QwtPointMapper::toPolygon | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | 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.

## ◆ toPolygonF()

QPolygonF QwtPointMapper::toPolygonF | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | 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.