Qwt User's Guide 6.1.0

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QwtPlotCurve Class Reference

A plot item, that represents a series of points. More...

`#include <qwt_plot_curve.h>`

Inheritance diagram for QwtPlotCurve:
[legend]

## Public Types
enum | CurveStyle { NoCurve = -1, Lines, Sticks, Steps, Dots, UserCurve = 100 }
enum | CurveAttribute { Inverted = 0x01, Fitted = 0x02 }
enum | LegendAttribute { LegendNoAttribute = 0x00, LegendShowLine = 0x01, LegendShowSymbol = 0x02, LegendShowBrush = 0x04 }
enum | PaintAttribute { ClipPolygons = 0x01, FilterPoints = 0x02, MinimizeMemory = 0x04, ImageBuffer = 0x08 }
typedef QFlags< CurveAttribute > | CurveAttributes
| Curve attributes.
typedef QFlags< LegendAttribute > | LegendAttributes
| Legend attributes.
typedef QFlags< PaintAttribute > | PaintAttributes
| Paint attributes.

## Public Member Functions
| QwtPlotCurve (const QString &title=QString::null)
| QwtPlotCurve (const QwtText &title)
virtual | ~QwtPlotCurve ()
| Destructor.
virtual int | rtti () const
void | setPaintAttribute (PaintAttribute, bool on=true)
bool | testPaintAttribute (PaintAttribute) const
void | setLegendAttribute (LegendAttribute, bool on=true)
bool | testLegendAttribute (LegendAttribute) const
void | setRawSamples (const double *xData, const double *yData, int size)
| Initialize the data by pointing to memory blocks which are not managed by QwtPlotCurve. More...
void | setSamples (const double *xData, const double *yData, int size)
void | setSamples (const QVector< double > &xData, const QVector< double > &yData)
| Initialize data with x- and y-arrays (explicitly shared) More...
void | setSamples (const QVector< QPointF > &)
void | setSamples (QwtSeriesData< QPointF > *)
int | closestPoint (const QPoint &pos, double *dist=NULL) const
double | minXValue () const
| boundingRect().left()
double | maxXValue () const
| boundingRect().right()
double | minYValue () const
| boundingRect().top()
double | maxYValue () const
| boundingRect().bottom()
void | setCurveAttribute (CurveAttribute, bool on=true)
bool | testCurveAttribute (CurveAttribute) const
void | setPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
void | setPen (const QPen &)
const QPen & | pen () const
void | setBrush (const QBrush &)
| Assign a brush. More...
const QBrush & | brush () const
void | setBaseline (double)
| Set the value of the baseline. More...
double | baseline () const
void | setStyle (CurveStyle style)
CurveStyle | style () const
void | setSymbol (QwtSymbol *)
| Assign a symbol. More...
const QwtSymbol * | symbol () const
void | setCurveFitter (QwtCurveFitter *)
QwtCurveFitter * | curveFitter () const
virtual void | drawSeries (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual QwtGraphic | legendIcon (int index, const QSizeF &) const
Public Member Functions inherited from QwtPlotSeriesItem
| QwtPlotSeriesItem (const QString &title=QString::null)
| QwtPlotSeriesItem (const QwtText &title)
virtual | ~QwtPlotSeriesItem ()
| Destructor.
void | setOrientation (Qt::Orientation)
Qt::Orientation | orientation () const
virtual void | draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &) const
| Draw the complete series. More...
virtual QRectF | boundingRect () const
virtual void | updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
| Update the item to changes of the axes scale division. More...
Public Member Functions inherited from QwtPlotItem
| QwtPlotItem (const QwtText &title=QwtText())
virtual | ~QwtPlotItem ()
| Destroy the QwtPlotItem.
void | attach (QwtPlot *plot)
| Attach the item to a plot. More...
void | detach ()
| This method detaches a QwtPlotItem from any QwtPlot it has been associated with. More...
QwtPlot * | plot () const
| Return attached plot.
void | setTitle (const QString &title)
void | setTitle (const QwtText &title)
const QwtText & | title () const
void | setItemAttribute (ItemAttribute, bool on=true)
bool | testItemAttribute (ItemAttribute) const
void | setItemInterest (ItemInterest, bool on=true)
bool | testItemInterest (ItemInterest) const
void | setRenderHint (RenderHint, bool on=true)
bool | testRenderHint (RenderHint) const
void | setRenderThreadCount (uint numThreads)
uint | renderThreadCount () const
void | setLegendIconSize (const QSize &)
QSize | legendIconSize () const
double | z () const
void | setZ (double z)
| Set the z value. More...
void | show ()
| Show the item.
void | hide ()
| Hide the item.
virtual void | setVisible (bool)
bool | isVisible () const
void | setAxes (int xAxis, int yAxis)
void | setXAxis (int axis)
int | xAxis () const
| Return xAxis.
void | setYAxis (int axis)
int | yAxis () const
| Return yAxis.
virtual void | itemChanged ()
virtual void | legendChanged ()
virtual void | getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasSize, double &left, double &top, double &right, double &bottom) const
| Calculate a hint for the canvas margin. More...
virtual void | updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
| Update the item to changes of the legend info. More...
QRectF | scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
| Calculate the bounding scale rectangle of 2 maps. More...
QRectF | paintRect (const QwtScaleMap &, const QwtScaleMap &) const
| Calculate the bounding paint rectangle of 2 maps. More...
virtual QList< QwtLegendData > | legendData () const
| Return all information, that is needed to represent the item on the legend. More...
Public Member Functions inherited from QwtSeriesStore< QPointF >
| QwtSeriesStore ()
| Constructor The store contains no series.
| ~QwtSeriesStore ()
| Destructor.
void | setData (QwtSeriesData< QPointF > *series)
QwtSeriesData< QPointF > * | data ()
const QwtSeriesData< QPointF > * | data () const
QPointF | sample (int index) const
virtual size_t | dataSize () const
virtual QRectF | dataRect () const
virtual void | setRectOfInterest (const QRectF &rect)
QwtSeriesData< QPointF > * | swapData (QwtSeriesData< QPointF > *series)

## Protected Member Functions
void | init ()
| Initialize internal members.
virtual void | drawCurve (QPainter *p, int style, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
| Draw the line part (without symbols) of a curve interval. More...
virtual void | drawSymbols (QPainter *p, const QwtSymbol &, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual void | drawLines (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
| Draw lines. More...
virtual void | drawSticks (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual void | drawDots (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual void | drawSteps (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual void | fillCurve (QPainter *, const QwtScaleMap &, const QwtScaleMap &, const QRectF &canvasRect, QPolygonF &) const
void | closePolyline (QPainter *, const QwtScaleMap &, const QwtScaleMap &, QPolygonF &) const
| Complete a polygon to be a closed polygon including the area between the original polygon and the baseline. More...
Protected Member Functions inherited from QwtPlotSeriesItem
virtual void | dataChanged ()
| dataChanged() indicates, that the series has been changed.
Protected Member Functions inherited from QwtPlotItem
QwtGraphic | defaultIcon (const QBrush &, const QSizeF &) const
| Return a default icon from a brush. More...
Protected Member Functions inherited from QwtAbstractSeriesStore
virtual | ~QwtAbstractSeriesStore ()
| Destructor.

## Detailed Description

A plot item, that represents a series of points.

A curve is the representation of a series of points in the x-y plane. It supports different display styles, interpolation ( f.e. spline ) and symbols.

Usage
  a) Assign curve properties
    When a curve is created, it is configured to draw black solid lines with in QwtPlotCurve::Lines style and no symbols. You can change this by calling setPen(), setStyle() and setSymbol().
  b) Connect/Assign data.
    QwtPlotCurve gets its points using a QwtSeriesData object offering a bridge to the real storage of the points ( like QAbstractItemModel ). There are several convenience classes derived from QwtSeriesData, that also store the points inside ( like QStandardItemModel ). QwtPlotCurve also offers a couple of variations of setSamples(), that build QwtSeriesData objects from arrays internally.
  c) Attach the curve to a plot
    See QwtPlotItem::attach()

Example:
  see examples/bode

See Also
  QwtPointSeriesData, QwtSymbol, QwtScaleMap

## Member Enumeration Documentation

enum QwtPlotCurve::CurveAttribute

Attribute for drawing the curve

See Also
  setCurveAttribute(), testCurveAttribute(), curveFitter()

Enumerator
Inverted | For QwtPlotCurve::Steps only. Draws a step function from the right to the left.
Fitted | Only in combination with QwtPlotCurve::Lines A QwtCurveFitter tries to interpolate/smooth the curve, before it is painted. Note Curve fitting requires temporary memory for calculating coefficients and additional points. If painting in QwtPlotCurve::Fitted mode is slow it might be better to fit the points, before they are passed to QwtPlotCurve.

enum QwtPlotCurve::CurveStyle

Curve styles.

See Also
  setStyle(), style()

Enumerator
NoCurve | Don't draw a curve. Note: This doesn't affect the symbols.
Lines | Connect the points with straight lines. The lines might be interpolated depending on the 'Fitted' attribute. Curve fitting can be configured using setCurveFitter().
Sticks | Draw vertical or horizontal sticks ( depending on the orientation() ) from a baseline which is defined by setBaseline().
Steps | Connect the points with a step function. The step function is drawn from the left to the right or vice versa, depending on the QwtPlotCurve::Inverted attribute.
Dots | Draw dots at the locations of the data points. Note: This is different from a dotted line (see setPen()), and faster as a curve in QwtPlotCurve::NoStyle style and a symbol painting a point.
UserCurve | Styles >= QwtPlotCurve::UserCurve are reserved for derived classes of QwtPlotCurve that overload drawCurve() with additional application specific curve types.

enum QwtPlotCurve::LegendAttribute

Attributes how to represent the curve on the legend

See Also
  setLegendAttribute(), testLegendAttribute(), QwtPlotItem::legendData(), legendIcon()

Enumerator
LegendNoAttribute | QwtPlotCurve tries to find a color representing the curve and paints a rectangle with it.
LegendShowLine | If the style() is not QwtPlotCurve::NoCurve a line is painted with the curve pen().
LegendShowSymbol | If the curve has a valid symbol it is painted.
LegendShowBrush | If the curve has a brush a rectangle filled with the curve brush() is painted.

enum QwtPlotCurve::PaintAttribute

Attributes to modify the drawing algorithm. The default setting enables ClipPolygons | FilterPoints

See Also
  setPaintAttribute(), testPaintAttribute()

Enumerator
ClipPolygons | Clip polygons before painting them. In situations, where points are far outside the visible area (f.e when zooming deep) this might be a substantial improvement for the painting performance
FilterPoints | Tries to reduce the data that has to be painted, by sorting out duplicates, or paintings outside the visible area. Might have a notable impact on curves with many close points. Only a couple of very basic filtering algorithms are implemented.
MinimizeMemory | Minimize memory usage that is temporarily needed for the translated points, before they get painted. This might slow down the performance of painting
ImageBuffer | Render the points to a temporary image and paint the image. This is a very special optimization for Dots style, when having a huge amount of points. With a reasonable number of points QPainter::drawPoints() will be faster.

## Constructor & Destructor Documentation

QwtPlotCurve::QwtPlotCurve | ( | const QString & | title = `QString::null` | ) |
| explicit

Constructor

Parameters

  title | Title of the curve

QwtPlotCurve::QwtPlotCurve | ( | const QwtText & | title | ) |
| explicit

Constructor

Parameters

  title | Title of the curve

## Member Function Documentation

double QwtPlotCurve::baseline | ( |  | ) | const

Returns
  Value of the baseline

See Also
  setBaseline()

const QBrush & QwtPlotCurve::brush | ( |  | ) | const

Returns
  Brush used to fill the area between lines and the baseline

See Also
  setBrush(), setBaseline(), baseline()

void QwtPlotCurve::closePolyline | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | QPolygonF & | polygon
| ) |  | const
| protected

Complete a polygon to be a closed polygon including the area between the original polygon and the baseline.

Parameters

  painter | Painter
  xMap | X map
  yMap | Y map
  polygon | Polygon to be completed

int QwtPlotCurve::closestPoint | ( | const QPoint & | pos,
|  | double * | dist = `NULL`
| ) |  | const

Find the closest curve point for a specific position

Parameters

  pos | Position, where to look for the closest curve point
  dist | If dist != NULL, closestPoint() returns the distance between the position and the closest curve point

Returns
  Index of the closest curve point, or -1 if none can be found ( f.e when the curve has no points )

Note
  closestPoint() implements a dumb algorithm, that iterates over all points

QwtCurveFitter * QwtPlotCurve::curveFitter | ( |  | ) | const

Get the curve fitter. If curve fitting is disabled NULL is returned.

Returns
  Curve fitter

See Also
  setCurveFitter(), Fitted

void QwtPlotCurve::drawCurve | ( | QPainter * | painter,
|  | int | style,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const
| protected virtual

Draw the line part (without symbols) of a curve interval.

Parameters

  painter | Painter
  style | curve style, see QwtPlotCurve::CurveStyle
  xMap | x map
  yMap | y map
  canvasRect | Contents rectangle of the canvas
  from | index of the first point to be painted
  to | index of the last point to be painted

See Also
  draw(), drawDots(), drawLines(), drawSteps(), drawSticks()

void QwtPlotCurve::drawDots | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const
| protected virtual

Draw dots

Parameters

  painter | Painter
  xMap | x map
  yMap | y map
  canvasRect | Contents rectangle of the canvas
  from | index of the first point to be painted
  to | index of the last point to be painted

See Also
  draw(), drawCurve(), drawSticks(), drawLines(), drawSteps()

void QwtPlotCurve::drawLines | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const
| protected virtual

Draw lines.

If the CurveAttribute Fitted is enabled a QwtCurveFitter tries to interpolate/smooth the curve, before it is painted.

Parameters

  painter | Painter
  xMap | x map
  yMap | y map
  canvasRect | Contents rectangle of the canvas
  from | index of the first point to be painted
  to | index of the last point to be painted

See Also
  setCurveAttribute(), setCurveFitter(), draw(), drawLines(), drawDots(), drawSteps(), drawSticks()

void QwtPlotCurve::drawSeries | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const
| virtual

Draw an interval of the curve

Parameters

  painter | Painter
  xMap | Maps x-values into pixel coordinates.
  yMap | Maps y-values into pixel coordinates.
  canvasRect | Contents rectangle of the canvas
  from | Index of the first point to be painted
  to | Index of the last point to be painted. If to < 0 the curve will be painted to its last point.

See Also
  drawCurve(), drawSymbols(),

Implements QwtPlotSeriesItem.

void QwtPlotCurve::drawSteps | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const
| protected virtual

Draw step function

The direction of the steps depends on Inverted attribute.

Parameters

  painter | Painter
  xMap | x map
  yMap | y map
  canvasRect | Contents rectangle of the canvas
  from | index of the first point to be painted
  to | index of the last point to be painted

See Also
  CurveAttribute, setCurveAttribute(), draw(), drawCurve(), drawDots(), drawLines(), drawSticks()

void QwtPlotCurve::drawSticks | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const
| protected virtual

Draw sticks

Parameters

  painter | Painter
  xMap | x map
  yMap | y map
  canvasRect | Contents rectangle of the canvas
  from | index of the first point to be painted
  to | index of the last point to be painted

See Also
  draw(), drawCurve(), drawDots(), drawLines(), drawSteps()

void QwtPlotCurve::drawSymbols | ( | QPainter * | painter,
|  | const QwtSymbol & | symbol,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const
| protected virtual

Draw symbols

Parameters

  painter | Painter
  symbol | Curve symbol
  xMap | x map
  yMap | y map
  canvasRect | Contents rectangle of the canvas
  from | Index of the first point to be painted
  to | Index of the last point to be painted

See Also
  setSymbol(), drawSeries(), drawCurve()

void QwtPlotCurve::fillCurve | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | QPolygonF & | polygon
| ) |  | const
| protected virtual

Fill the area between the curve and the baseline with the curve brush

Parameters

  painter | Painter
  xMap | x map
  yMap | y map
  canvasRect | Contents rectangle of the canvas
  polygon | Polygon - will be modified !

See Also
  setBrush(), setBaseline(), setStyle()

QwtGraphic QwtPlotCurve::legendIcon | ( | int | index,
|  | const QSizeF & | size
| ) |  | const
| virtual

Returns
  Icon representing the curve on the legend

Parameters

  index | Index of the legend entry ( ignored as there is only one )
  size | Icon size

See Also
  QwtPlotItem::setLegendIconSize(), QwtPlotItem::legendData()

Reimplemented from QwtPlotItem.

const QPen & QwtPlotCurve::pen | ( |  | ) | const

Returns
  Pen used to draw the lines

See Also
  setPen(), brush()

int QwtPlotCurve::rtti | ( |  | ) | const
| virtual

Returns
  QwtPlotItem::Rtti_PlotCurve

Reimplemented from QwtPlotItem.

void QwtPlotCurve::setBaseline | ( | double | value | ) |

Set the value of the baseline.

The baseline is needed for filling the curve with a brush or the Sticks drawing style.

The interpretation of the baseline depends on the orientation(). With Qt::Horizontal, the baseline is interpreted as a horizontal line at y = baseline(), with Qt::Vertical, it is interpreted as a vertical line at x = baseline().

The default value is 0.0.

Parameters

  value | Value of the baseline

See Also
  baseline(), setBrush(), setStyle(), QwtPlotAbstractSeriesItem::orientation()

void QwtPlotCurve::setBrush | ( | const QBrush & | brush | ) |

Assign a brush.

In case of brush.style() != QBrush::NoBrush and style() != QwtPlotCurve::Sticks the area between the curve and the baseline will be filled.

In case !brush.color().isValid() the area will be filled by pen.color(). The fill algorithm simply connects the first and the last curve point to the baseline. So the curve data has to be sorted (ascending or descending).

Parameters

  brush | New brush

See Also
  brush(), setBaseline(), baseline()

void QwtPlotCurve::setCurveAttribute | ( | CurveAttribute | attribute,
|  | bool | on = `true`
| ) |  |

Specify an attribute for drawing the curve

Parameters

  attribute | Curve attribute
  on | On/Off

/sa testCurveAttribute(), setCurveFitter()

void QwtPlotCurve::setCurveFitter | ( | QwtCurveFitter * | curveFitter | ) |

Assign a curve fitter

The curve fitter "smooths" the curve points, when the Fitted CurveAttribute is set. setCurveFitter(NULL) also disables curve fitting.

The curve fitter operates on the translated points ( = widget coordinates) to be functional for logarithmic scales. Obviously this is less performant for fitting algorithms, that reduce the number of points.

For situations, where curve fitting is used to improve the performance of painting huge series of points it might be better to execute the fitter on the curve points once and to cache the result in the QwtSeriesData object.

Parameters

  curveFitter() | Curve fitter

See Also
  Fitted

void QwtPlotCurve::setLegendAttribute | ( | LegendAttribute | attribute,
|  | bool | on = `true`
| ) |  |

Specify an attribute how to draw the legend icon

Parameters

  attribute | Attribute
  on | On/Off /sa testLegendAttribute(). legendIcon()

void QwtPlotCurve::setPaintAttribute | ( | PaintAttribute | attribute,
|  | bool | on = `true`
| ) |  |

Specify an attribute how to draw the curve

Parameters

  attribute | Paint attribute
  on | On/Off

See Also
  testPaintAttribute()

void QwtPlotCurve::setPen | ( | const QColor & | color,
|  | qreal | width = `0.0`,
|  | Qt::PenStyle | style = `Qt::SolidLine`
| ) |  |

Build and assign a pen

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic ( see QPen::isCosmetic() ). This method has been introduced to hide this incompatibility.

Parameters

  color | Pen color
  width | Pen width
  style | Pen style

See Also
  pen(), brush()

void QwtPlotCurve::setPen | ( | const QPen & | pen | ) |

Assign a pen

Parameters

  pen | New pen

See Also
  pen(), brush()

void QwtPlotCurve::setRawSamples | ( | const double * | xData,
|  | const double * | yData,
|  | int | size
| ) |  |

Initialize the data by pointing to memory blocks which are not managed by QwtPlotCurve.

setRawSamples is provided for efficiency. It is important to keep the pointers during the lifetime of the underlying QwtCPointerData class.

Parameters

  xData | pointer to x data
  yData | pointer to y data
  size | size of x and y

See Also
  QwtCPointerData

void QwtPlotCurve::setSamples | ( | const double * | xData,
|  | const double * | yData,
|  | int | size
| ) |  |

Set data by copying x- and y-values from specified memory blocks. Contrary to setRawSamples(), this function makes a 'deep copy' of the data.

Parameters

  xData | pointer to x values
  yData | pointer to y values
  size | size of xData and yData

See Also
  QwtPointArrayData

void QwtPlotCurve::setSamples | ( | const QVector< double > & | xData,
|  | const QVector< double > & | yData
| ) |  |

Initialize data with x- and y-arrays (explicitly shared)

Parameters

  xData | x data
  yData | y data

See Also
  QwtPointArrayData

void QwtPlotCurve::setSamples | ( | const QVector< QPointF > & | samples | ) |

Initialize data with an array of points.

Parameters

  samples | Vector of points

Note
  QVector is implicitly shared
  QPolygonF is derived from QVector<QPointF>

void QwtPlotCurve::setSamples | ( | QwtSeriesData< QPointF > * | data | ) |

Assign a series of points

setSamples() is just a wrapper for setData() without any additional value - beside that it is easier to find for the developer.

Parameters

  data | Data

Warning
  The item takes ownership of the data object, deleting it when its not used anymore.

void QwtPlotCurve::setStyle | ( | CurveStyle | style | ) |

Set the curve's drawing style

Parameters

  style | Curve style

See Also
  style()

void QwtPlotCurve::setSymbol | ( | QwtSymbol * | symbol | ) |

Assign a symbol.

The curve will take the ownership of the symbol, hence the previously set symbol will be delete by setting a new one. If `symbol` is `NULL` no symbol will be drawn.

Parameters

  symbol | Symbol

See Also
  symbol()

QwtPlotCurve::CurveStyle QwtPlotCurve::style | ( |  | ) | const

Returns
  Style of the curve

See Also
  setStyle()

const QwtSymbol * QwtPlotCurve::symbol | ( |  | ) | const

Returns
  Current symbol or NULL, when no symbol has been assigned

See Also
  setSymbol()

bool QwtPlotCurve::testCurveAttribute | ( | CurveAttribute | attribute | ) | const

Returns
  true, if attribute is enabled

See Also
  setCurveAttribute()

bool QwtPlotCurve::testLegendAttribute | ( | LegendAttribute | attribute | ) | const

Returns
  True, when attribute is enabled

See Also
  setLegendAttribute()

bool QwtPlotCurve::testPaintAttribute | ( | PaintAttribute | attribute | ) | const

Returns
  True, when attribute is enabled

See Also
  setPaintAttribute()