---

QwtCurve Class Reference

A class which draws curves. More...

#include <qwt_curve.h>

Inheritance diagram for QwtCurve::

List of all members.

Public Types
enum	CurveStyle {   NoCurve, Lines, Sticks, Steps,   Dots, Spline, UserCurve = 100 }
enum	CurveOption {   Auto = 0, Yfx = 1, Xfy = 2, Parametric = 4,   Periodic = 8, Inverted = 16 }
Public Methods
	QwtCurve (const QString &title=QString::null)
	QwtCurve (const QwtCurve &c)
virtual	~QwtCurve ()
virtual const QwtCurve &	operator= (const QwtCurve &c)
void	setRawData (double *x, double *y, int size)
void	setData (double *x, double *y, int size)
int	dataSize () const
double	x (int i) const
double	y (int i) const
virtual double	minXValue () const
virtual double	maxXValue () const
virtual double	minYValue () const
virtual double	maxYValue () const
void	setOptions (int t)
int	options () const
void	setTitle (const QString &title)
const QString &	title () const
void	setPen (const QPen &p)
const QPen &	pen () const
void	setBaseline (double ref)
double	baseline () const
void	setStyle (int style, int options=0)
int	style () const
void	setSymbol (const QwtSymbol &s)
const QwtSymbol &	symbol () const
void	setSplineSize (int s)
int	splineSize () const
virtual void	draw (QPainter *p, const QwtDiMap &xMap, const QwtDiMap &yMap, int from=0, int to=-1)
Static Public Methods
void	drawPoint (QPainter *, int x, int y)
void	drawLine (QPainter *, int x1, int y1, int x2, int y2)
void	drawPolyline (QPainter *, const QPointArray &)
Protected Methods
void	init (const QString &title)
void	copy (const QwtCurve &c)
virtual void	drawCurve (QPainter *p, int style, const QwtDiMap &xMap, const QwtDiMap &yMap, int from, int to)
virtual void	drawSymbols (QPainter *p, QwtSymbol &, const QwtDiMap &xMap, const QwtDiMap &yMap, int from, int to)
void	drawLines (QPainter *p, const QwtDiMap &xMap, const QwtDiMap &yMap, int from, int to)
void	drawSticks (QPainter *p, const QwtDiMap &xMap, const QwtDiMap &yMap, int from, int to)
void	drawDots (QPainter *p, const QwtDiMap &xMap, const QwtDiMap &yMap, int from, int to)
void	drawSteps (QPainter *p, const QwtDiMap &xMap, const QwtDiMap &yMap, int from, int to)
void	drawSpline (QPainter *p, const QwtDiMap &xMap, const QwtDiMap &yMap)
virtual void	curveChanged ()
int	verifyRange (int &i1, int &i2)
Protected Attributes
bool	d_raw
QArray< double >	d_x
QArray< double >	d_y
QwtSpline	d_spx
QwtSpline	d_spy

---

Detailed Description

A class which draws curves.

This class can be used to display data as a curve in the x-y plane. It supports different display styles, spline interpolation and symbols.

Usage

A. Assign Properties

When a curve is created, it is configured to draw black solid lines with QwtCurve::Lines and no symbols. You can change this by calling QwtCurve::setPen(), QwtCurve::setStyle() and QwtCurve::setSymbol().

B. Assign or change data.

Data can be assigned in two ways:

• QwtCurve::setData() copies the x and y data from the specified arrays into its internal buffer.
• QwtCurve::setRawData() does not make a copy of the data, but only stores the pointers and size information instead. This function is less safe (you must not delete the data while they are attached), but more efficient, and more convenient if the data change dynamically.

C. Draw

QwtCurve::drawCurve() maps the curve points into pixel coordinates and paints them.

Example:

see examples/curvdemo

See also:

QwtSymbol, QwtDiMap

---

Member Enumeration Documentation

enum QwtCurve::CurveOption

Curve options. See also: QwtCurve::setOptions

enum QwtCurve::CurveStyle

Curve styles. See also: QwtCurve::setStyle

---

Constructor & Destructor Documentation

QwtCurve::QwtCurve (  const QString &    title = QString::null )

Ctor. Parameters: title  title of the curve

QwtCurve::QwtCurve (  const QwtCurve &    c )

Copy Constructor. Warning: If curve c has attached its data in raw mode (see QwtCurve::setRawData), the copy constructor creates a deep copy of the data. The data are implicitly shared otherwise.

QwtCurve::~QwtCurve (    )  [virtual]

Dtor.

---

Member Function Documentation

double QwtCurve::baseline (    )  const

Return the value of the baseline. See also: QwtCurve::setBaseline

void QwtCurve::copy (  const QwtCurve &    c )  [protected]

Copy the contents of a curve into another curve.

void QwtCurve::curveChanged (    )  [protected, virtual]

Notify a change of attributes. This virtual function is called when an attribute of the curve has changed. It can be redefined by derived classes. The default implementation does nothing. Reimplemented in QwtPlotCurve.

int QwtCurve::dataSize (    )  const

Return the size of the data arrays.

void QwtCurve::draw (  QPainter *    painter, const QwtDiMap &    xMap, const QwtDiMap &    yMap, int    from = 0, int    to = -1 )  [virtual]

Draw an intervall of the curve. Parameters: p  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: qwt_drawPoint, qwt_drawLine, qwt_drawPolyline

void QwtCurve::drawCurve (  QPainter *    painter, int    style, const QwtDiMap &    xMap, const QwtDiMap &    yMap, int    from, int    to )  [protected, virtual]

Draw the line part (without symbols) of a curve interval. 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: qwt_drawPoint, qwt_drawLine, qwt_drawPolyline

void QwtCurve::drawDots (  QPainter *    painter, const QwtDiMap &    xMap, const QwtDiMap &    yMap, int    from, int    to )  [protected]

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: qwt_drawPoint, qwt_drawLine, qwt_drawPolyline

void QwtCurve::drawLine (  QPainter *    painter, int    x1, int    y1, int    x2, int    y2 )  [static]

Wrapper for painter->drawLine(x1, y1, x2, y2). On X11 the cutting points with [-16384 .. 16384] will be calculated. Everything outside will be skipped to avoid overruns.

void QwtCurve::drawLines (  QPainter *    painter, const QwtDiMap &    xMap, const QwtDiMap &    yMap, int    from, int    to )  [protected]

Draw lines. 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: qwt_drawPoint, qwt_drawLine, qwt_drawPolyline

void QwtCurve::drawPoint (  QPainter *    painter, int    x, int    y )  [static]

Wrapper for painter->drawPoint(x, y). On X11 points outside [-16384 .. 16384] will be skipped to avoid overruns.

void QwtCurve::drawPolyline (  QPainter *    painter, const QPointArray &    pa )  [static]

Wrapper for painter->drawPolyline(x1, y1, x2, y2). On X11 the cutting points with [-16384 .. 16384] will be calculated. Everything outside will be skipped to avoid overruns.

void QwtCurve::drawSpline (  QPainter *    painter, const QwtDiMap &    xMap, const QwtDiMap &    yMap )  [protected]

Draw a spline. 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: qwt_drawPoint, qwt_drawLine, qwt_drawPolyline

void QwtCurve::drawSteps (  QPainter *    painter, const QwtDiMap &    xMap, const QwtDiMap &    yMap, int    from, int    to )  [protected]

Draw step function. Parameters: p  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: qwt_drawPoint, qwt_drawLine, qwt_drawPolyline

void QwtCurve::drawSticks (  QPainter *    painter, const QwtDiMap &    xMap, const QwtDiMap &    yMap, int    from, int    to )  [protected]

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: qwt_drawPoint, qwt_drawLine, qwt_drawPolyline

void QwtCurve::drawSymbols (  QPainter *    painter, QwtSymbol &    symbol, const QwtDiMap &    xMap, const QwtDiMap &    yMap, int    from, int    to )  [protected, virtual]

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

void QwtCurve::init (  const QString &    title )  [protected]

Initialize data members.

double QwtCurve::maxXValue (    )  const [virtual]

find the largest x value.

double QwtCurve::maxYValue (    )  const [virtual]

find the largest y value.

double QwtCurve::minXValue (    )  const [virtual]

find the smallest x value.

double QwtCurve::minYValue (    )  const [virtual]

find the smallest y value.

const QwtCurve & QwtCurve::operator= (  const QwtCurve &    c )  [virtual]

Copy Assignment. Warning: If curve c has attached its data in raw mode, the assignment operator creates a deep copy of the data. The data are implicitly shared otherwise. See also: QwtCurve::setRawData()

int QwtCurve::options (    )  const

Return the current style options. See also: QwtCurve::setOptions

const QPen & QwtCurve::pen (    )  const

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

void QwtCurve::setBaseline (  double    ref )

Set the value of the baseline. The baseline is needed for the QwtCurve::Sticks drawing style. The default value is 0.0. The interpretation of the baseline depends on the style options. With QwtCurve::Yfx, the baseline is interpreted as a horizontal line at y = baseline(), with QwtCurve::Yfy, it is interpreted as a vertical line at x = baseline(). Parameters: ref  baseline See also: QwtCurve::setStyle(), QwtCurve::setOptions()

void QwtCurve::setData (  double *    x, double *    y, int    size )

Copy x-y data from specified arrays. Parameters: x  pointer to x data y  pointer to y data size  size of x and y

void QwtCurve::setOptions (  int    opt )

Specify options for the drawing style. The options can be used to modify the drawing style. Options can be or-combined. The following options are defined: QwtCurve::Auto The default setting. For QwtCurve::spline, this means that the type of the spline is determined automatically, depending on the data. For all other styles, this means that y is regarded as a function of x. QwtCurve::Yfx Draws y as a function of x (the default). The baseline is interpreted as a horizontal line with y = baseline(). QwtCurve::Xfy Draws x as a function of y. The baseline is interpreted as a vertical line with x = baseline(). QwtCurve::Parametric For QwtCurve::Spline only. Draws a parametric spline. QwtCurve::Periodic For QwtCurve::Spline only. Draws a periodic spline. QwtCurve::Inverted For QwtCurve::Steps only. Draws a step function from the right to the left. Parameters: opt  new options /sa QwtCurve::options()

void QwtCurve::setPen (  const QPen &    p )

Assign a pen. Parameters: p  New pen

void QwtCurve::setRawData (  double *    x, double *    y, int    size )

Attach raw data. setRawData is provided for efficiency. In contrast to setData, it does not copy the data, so it is important to keep the pointers valid while they are attached. The QwtCurve destructor does not delete the attached data, so you can safely call setRawData and setData several times subsequently. Parameters: x  pointer to x data y  pointer to y data size  size of x and y

void QwtCurve::setSplineSize (  int    s )

Change the number of interpolated points. Parameters: s  new size Warning: The default is 250 points.

void QwtCurve::setStyle (  int    style, int    options = 0 )

Set the curve's drawing style. Valid styles are: QwtCurve::NoCurve Don't draw a curve. Note: This doesn't affect the symbol. QwtCurve::Lines Connect the points with straight lines. QwtCurve::Sticks Draw vertical sticks from a baseline which is defined by setBaseline(). QwtCurve::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' option. QwtCurves::Dots Draw dots at the locations of the data points. Note: This is different from a dotted line (see setPen()). QwtCurve::Spline Interpolate the points with a spline. The spline type can be specified with setOptions(), the size of the spline (= number of interpolated points) can be specified with setSplineSize(). QwtCurve::UserCurve ... Styles >= QwtCurve::UserCurve are reserved for derived classes of QwtCurve that overload QwtCurve::draw() with additional application specific curve types. See also: QwtCurve::style()

void QwtCurve::setSymbol (  const QwtSymbol &    s )

Assign a symbol. Parameters: s  symbol See also: QwtSymbol

void QwtCurve::setTitle (  const QString &    title )

Assign a title to a curve. Parameters: title  new title

int QwtCurve::splineSize (    )  const

Return the spline size. See also: QwtCurve::setSplineSize

int QwtCurve::style (    )  const

Return the current style. See also: QwtCurve::setStyle

const QwtSymbol & QwtCurve::symbol (    )  const

Return the current symbol. See also: QwtCurve::setSymbol

const QString & QwtCurve::title (    )  const

Return the title. See also: QwtCurve::setTitle

int QwtCurve::verifyRange (  int &    i1, int &    i2 )  [protected]

Checks if a range of indices is valid and corrects it if necessary. Parameters: i1  Index 1 i2  Index 2

double QwtCurve::x (  int    i )  const

Parameters: i  index Returns: x-value at position i

double QwtCurve::y (  int    i )  const

Parameters: i  index Returns: y-value at position i

---