QwtPlotCurve (3)

#include <qwt_plot_curve.h>

Inherits QwtPlotItem.

Public Types

enum CurveAttribute { Inverted = 1, Fitted = 2 }

enum CurveStyle { NoCurve, Lines, Sticks, Steps, Dots, UserCurve = 100 }

enum CurveType { Yfx, Xfy }

enum PaintAttribute { PaintFiltered = 1, ClipPolygons = 2 }

Public Member Functions

QwtPlotCurve ()

QwtPlotCurve (const QwtText &title)

QwtPlotCurve (const QString &title)

virtual ~QwtPlotCurve ()

double baseline () const

virtual QwtDoubleRect boundingRect () const

const QBrush & brush () const

int closestPoint (const QPoint &pos, double *dist=NULL) const

QwtCurveFitter * curveFitter () const

CurveType curveType () const

QwtData & data ()

const QwtData & data () const

int dataSize () const

virtual void draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &) const

virtual void draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

void draw (int from, int to) const

double maxXValue () const

double maxYValue () const

double minXValue () const

double minYValue () const

const QPen & pen () const

virtual int rtti () const

void setBaseline (double ref)

void setBrush (const QBrush &)

void setCurveAttribute (CurveAttribute, bool on=true)

void setCurveFitter (QwtCurveFitter *)

void setCurveType (CurveType)

void setData (const double *xData, const double *yData, int size)

void setData (const QwtArray< double > &xData, const QwtArray< double > &yData)

void setData (const QPolygonF &data)

void setData (const QwtData &data)

void setPaintAttribute (PaintAttribute, bool on=true)

void setPen (const QPen &)

void setRawData (const double *x, const double *y, int size)

void setStyle (CurveStyle style)

void setSymbol (const QwtSymbol &s)

CurveStyle style () const

const QwtSymbol & symbol () const

bool testCurveAttribute (CurveAttribute) const

bool testPaintAttribute (PaintAttribute) const

virtual void updateLegend (QwtLegend *) const

double x (int i) const

double y (int i) const

Protected Member Functions

void closePolyline (const QwtScaleMap &, const QwtScaleMap &, QwtPolygon &) const

virtual void drawCurve (QPainter *p, int style, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

void drawDots (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

void drawLines (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

void drawSteps (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

void drawSticks (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

virtual void drawSymbols (QPainter *p, const QwtSymbol &, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

void fillCurve (QPainter *, const QwtScaleMap &, const QwtScaleMap &, QwtPolygon &) const

void init ()

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 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 QwtData object offering a bridge to the real storage of the points ( like QAbstractItemModel ). There are several convenience classes derived from QwtData, that also store the points inside ( like QStandardItemModel ). QwtPlotCurve also offers a couple of variations of setData(), that build QwtData objects from arrays internally.

c) Attach the curve to a plot

See QwtPlotItem::attach()

Example:

see examples/bode

See also:

QwtPlot, QwtData, QwtSymbol, QwtScaleMap

enum \fBQwtPlotCurve::CurveAttribute\fP

Attribute for drawing the curve

• Fitted ( in combination with the Lines QwtPlotCurve::CurveStyle only )

  A QwtCurveFitter tries to interpolate/smooth the curve, before it is painted. Note that curve fitting requires temorary memory for calculating coefficients and additional points. If painting in Fitted mode is slow it might be better to fit the points, before they are passed to QwtPlotCurve.

• Inverted

  For Steps only. Draws a step function from the right to the left.

See also:

setCurveAttribute(), testCurveAttribute(), curveFitter()

enum \fBQwtPlotCurve::CurveStyle\fP

Curve styles.

• 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(Yfx) or horizontal(Xfy) sticks 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 '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 NoStyle style and a symbol painting a point.

• UserCurve

  Styles >= UserCurve are reserved for derived classes of QwtPlotCurve that overload drawCurve() with additional application specific curve types.

See also:

setStyle(), style()

enum \fBQwtPlotCurve::CurveType\fP

Curve type.

• Yfx

  Draws y as a function of x (the default). The baseline is interpreted as a horizontal line with y = baseline().

• Xfy

  Draws x as a function of y. The baseline is interpreted as a vertical line with x = baseline().

The baseline is used for aligning the sticks, or filling the curve with a brush.

See also:

setCurveType(), curveType(), baseline() brush()

enum \fBQwtPlotCurve::PaintAttribute\fP

Attributes to modify the drawing algorithm.

• PaintFiltered

  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 algos are implemented.

• 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 ( especially on Windows ).

The default is, that no paint attributes are enabled.

See also:

setPaintAttribute(), testPaintAttribute()

QwtPlotCurve::QwtPlotCurve (const \fBQwtText\fP &title)\fC [explicit]\fP

Constructor

Parameters:

title Title of the curve

QwtPlotCurve::QwtPlotCurve (const QString &title)\fC [explicit]\fP

Constructor

Parameters:

title Title of the curve

double QwtPlotCurve::baseline () const

Return the value of the baseline

See also:

setBaseline()

QwtDoubleRect QwtPlotCurve::boundingRect () const\fC [virtual]\fP

Returns the bounding rectangle of the curve data. If there is no bounding rect, like for empty data the rectangle is invalid.

See also:

QwtData::boundingRect(), QwtDoubleRect::isValid()

Reimplemented from QwtPlotItem.

const QBrush & QwtPlotCurve::brush () const

Return the brush used to fill the area between lines and the baseline. See also:

setBrush(), setBaseline(), baseline()

void QwtPlotCurve::closePolyline (const \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, QwtPolygon &pa) const\fC [protected]\fP

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

xMap X map

yMap Y map

pa Polygon to be completed

int QwtPlotCurve::closestPoint (const QPoint &pos, double *dist = \fCNULL\fP) 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 clostest 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

\fBQwtCurveFitter\fP * QwtPlotCurve::curveFitter () const

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

Returns:

Curve fitter

\fBQwtPlotCurve::CurveType\fP QwtPlotCurve::curveType () const

Return the curve type

See also:

CurveType, setCurveType()

\fBQwtData\fP & QwtPlotCurve::data ()\fC [inline]\fP

Returns:

the the curve data

const \fBQwtData\fP & QwtPlotCurve::data () const\fC [inline]\fP

Returns:

the the curve data

int QwtPlotCurve::dataSize () const

Return the size of the data arrays

See also:

setData()

void QwtPlotCurve::draw (QPainter *painter, const \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, const QRect &canvasRect) const\fC [virtual]\fP

Draw the complete curve. Parameters:

painter Painter

xMap Maps x-values into pixel coordinates.

yMap Maps y-values into pixel coordinates.

See also:

drawCurve(), drawSymbols()

Implements QwtPlotItem.

void QwtPlotCurve::draw (QPainter *painter, const \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, intfrom, intto) const\fC [virtual]\fP

Draw an interval of the curve. Parameters:

painter Painter

xMap maps x-values into pixel coordinates.

yMap maps y-values into pixel coordinates.

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(),

void QwtPlotCurve::draw (intfrom, intto) const

Draw a set of points of a curve. When observing an measurement while it is running, new points have to be added to an existing curve. drawCurve can be used to display them avoiding a complete redraw of the canvas.

Setting plot()->canvas()->setAttribute(Qt::WA_PaintOutsidePaintEvent, true); will result in faster painting, if the paint engine of the canvas widget supports this feature.

Parameters:

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()

void QwtPlotCurve::drawCurve (QPainter *painter, intstyle, const \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, intfrom, intto) const\fC [protected]\fP, \fC [virtual]\fP

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

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 \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, intfrom, intto) const\fC [protected]\fP

Draw dots

Parameters:

painter Painter

xMap x map

yMap y map

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 \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, intfrom, intto) const\fC [protected]\fP

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

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::drawSteps (QPainter *painter, const \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, intfrom, intto) const\fC [protected]\fP

Draw step function

The direction of the steps depends on Inverted attribute.

Parameters:

painter Painter

xMap x map

yMap y map

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 \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, intfrom, intto) const\fC [protected]\fP

Draw sticks

Parameters:

painter Painter

xMap x map

yMap y map

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 \fBQwtSymbol\fP &symbol, const \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, intfrom, intto) const\fC [protected]\fP, \fC [virtual]\fP

Draw symbols. Parameters:

painter Painter

symbol Curve symbol

xMap x map

yMap y map

from index of the first point to be painted

to index of the last point to be painted

See also:

setSymbol(), draw(), drawCurve()

void QwtPlotCurve::fillCurve (QPainter *painter, const \fBQwtScaleMap\fP &xMap, const \fBQwtScaleMap\fP &yMap, QwtPolygon &pa) const\fC [protected]\fP

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

Parameters:

painter Painter

xMap x map

yMap y map

pa Polygon

See also:

setBrush(), setBaseline(), setCurveType()

const QPen & QwtPlotCurve::pen () const

Return the pen used to draw the lines. See also:

setPen(), brush()

int QwtPlotCurve::rtti () const\fC [virtual]\fP

Returns:

QwtPlotItem::Rtti_PlotCurve

Reimplemented from QwtPlotItem.

void QwtPlotCurve::setBaseline (doublereference)

Set the value of the baseline. The baseline is needed for filling the curve with a brush or the Sticks drawing style. The default value is 0.0. The interpretation of the baseline depends on the CurveType. With QwtPlotCurve::Yfx, the baseline is interpreted as a horizontal line at y = baseline(), with QwtPlotCurve::Yfy, it is interpreted as a vertical line at x = baseline().

Parameters:

reference baseline

See also:

baseline(), setBrush(), setStyle(), setCurveType()

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 (\fBCurveAttribute\fPattribute, boolon = \fCtrue\fP)

Specify an attribute for drawing the curve

Parameters:

attribute Curve attribute

on On/Off

/sa CurveAttribute, testCurveAttribute(), setCurveFitter()

void QwtPlotCurve::setCurveFitter (\fBQwtCurveFitter\fP *curveFitter)

Assign a curve fitter setCurveFitter(NULL) disables curve fitting.

Parameters:

curveFitter Curve fitter

void QwtPlotCurve::setCurveType (\fBCurveType\fPcurveType)

Assign the curve type

Parameters:

curveType Yfx or Xfy

See also:

CurveType, curveType()

void QwtPlotCurve::setData (const double *xData, const double *yData, intsize)

Set data by copying x- and y-values from specified memory blocks. Contrary to setCurveRawData(), 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

Note:

Internally the data is stored in a QwtArrayData object

void QwtPlotCurve::setData (const QwtArray< double > &xData, const QwtArray< double > &yData)

Initialize data with x- and y-arrays (explicitly shared) ( Builds an QwtArrayData object internally )

Parameters:

xData x data

yData y data

Note:

Internally the data is stored in a QwtArrayData object

void QwtPlotCurve::setData (const QPolygonF &data)

Initialize data with an array of points (explicitly shared).

Parameters:

data Data

Note:

Internally the data is stored in a QwtPolygonFData object

void QwtPlotCurve::setData (const \fBQwtData\fP &data)

Initialize data with a pointer to QwtData.

Parameters:

data Data

See also:

QwtData::copy()

void QwtPlotCurve::setPaintAttribute (\fBPaintAttribute\fPattribute, boolon = \fCtrue\fP)

Specify an attribute how to draw the curve

Parameters:

attribute Paint attribute

on On/Off /sa PaintAttribute, testPaintAttribute()

void QwtPlotCurve::setPen (const QPen &pen)

Assign a pen

The width of non cosmetic pens is scaled according to the resolution of the paint device.

Parameters:

pen New pen

See also:

pen(), brush(), QwtPainter::scaledPen()

void QwtPlotCurve::setRawData (const double *xData, const double *yData, intsize)

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

Note:

Internally the data is stored in a QwtCPointerData object

void QwtPlotCurve::setStyle (\fBCurveStyle\fPstyle)

Set the curve's drawing style

Parameters:

style Curve style

See also:

CurveStyle, style()

void QwtPlotCurve::setSymbol (const \fBQwtSymbol\fP &symbol)

Assign a symbol. Parameters:

symbol Symbol

See also:

symbol()

\fBQwtPlotCurve::CurveStyle\fP QwtPlotCurve::style () const

Return the current style

See also:

CurveStyle, setStyle()

const \fBQwtSymbol\fP & QwtPlotCurve::symbol () const

Return the current symbol. See also:

setSymbol()

bool QwtPlotCurve::testCurveAttribute (\fBCurveAttribute\fPattribute) const

Returns:

true, if attribute is enabled

See also:

CurveAttribute, setCurveAttribute()

bool QwtPlotCurve::testPaintAttribute (\fBPaintAttribute\fPattribute) const

Return the current paint attributes. See also:

PaintAttribute, setPaintAttribute()

double QwtPlotCurve::x (inti) const\fC [inline]\fP

Parameters:

i index

Returns:

x-value at position i

double QwtPlotCurve::y (inti) const\fC [inline]\fP

Parameters:

i index

Returns:

y-value at position i

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