Provided by: libqwt-doc_6.0.0-1.2_all 
NAME
QwtPlotCurve -
A plot item, that represents a series of points.
SYNOPSIS
#include <qwt_plot_curve.h>
Inherits QwtPlotSeriesItem< QPointF >.
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, CacheSymbols = 0x02 }
typedef QFlags< CurveAttribute > CurveAttributes
typedef QFlags< LegendAttribute > LegendAttributes
typedef QFlags< PaintAttribute > PaintAttributes
Public Member Functions
QwtPlotCurve (const QString &title=QString::null)
QwtPlotCurve (const QwtText &title)
virtual ~QwtPlotCurve ()
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)
void setSamples (const double *xData, const double *yData, int size)
void setSamples (const QVector< double > &xData, const QVector< double > &yData)
void setSamples (const QVector< QPointF > &)
int closestPoint (const QPoint &pos, double *dist=NULL) const
double minXValue () const
double maxXValue () const
double minYValue () const
double maxYValue () const
void setCurveAttribute (CurveAttribute, bool on=true)
bool testCurveAttribute (CurveAttribute) const
void setPen (const QPen &)
const QPen & pen () const
void setBrush (const QBrush &)
const QBrush & brush () const
void setBaseline (double ref)
double baseline () const
void setStyle (CurveStyle style)
CurveStyle style () const
void setSymbol (const QwtSymbol *s)
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 void updateLegend (QwtLegend *) const
virtual void drawLegendIdentifier (QPainter *, const QRectF &) const
Protected Member Functions
void init ()
virtual void drawCurve (QPainter *p, int style, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const
QRectF &canvasRect, int from, int to) const
virtual void drawSymbols (QPainter *p, const QwtSymbol &, const QwtScaleMap &xMap, const QwtScaleMap
&yMap, const QRectF &canvasRect, int from, int to) const
void drawLines (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect,
int from, int to) const
void drawSticks (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect,
int from, int to) const
void drawDots (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect,
int from, int to) const
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
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 Typedef Documentation
typedef QFlags<CurveAttribute> QwtPlotCurve::CurveAttributes
Curve attributes.
typedef QFlags<LegendAttribute> QwtPlotCurve::LegendAttributes
Legend attributes.
typedef QFlags<PaintAttribute> QwtPlotCurve::PaintAttributes
Paint attributes.
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 temorary 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(), drawLegendIdentifier()
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
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
CacheSymbols
Paint the symbol to a QPixmap and paint the pixmap instead rendering the symbol for each point.
The flag has no effect, when the curve is not painted to the canvas ( f.e when exporting the plot
to a PDF document ).
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
QwtPlotCurve::~QwtPlotCurve () [virtual]
Destructor.
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 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
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, intstyle, const QwtScaleMap &xMap, const QwtScaleMap &yMap,
const QRectF &canvasRect, intfrom, intto) 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 rect 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, intfrom, intto) const [protected] Draw dots
Parameters:
painter Painter
xMap x map
yMap y map
canvasRect Contents rect 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::drawLegendIdentifier (QPainter *painter, const QRectF &rect) const [virtual]
Draw the identifier representing the curve on the legend. Parameters:
painter Painter
rect Bounding rectangle for the identifier
See also:
setLegendAttribute(), QwtPlotItem::Legend
Reimplemented from QwtLegendItemManager.
void QwtPlotCurve::drawLines (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const
QRectF &canvasRect, intfrom, intto) const [protected]
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 rect 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, intfrom, intto) 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 rect 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 QwtPlotAbstractSeriesItem.
void QwtPlotCurve::drawSteps (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const
QRectF &canvasRect, intfrom, intto) const [protected] Draw step function
The direction of the steps depends on Inverted attribute.
Parameters:
painter Painter
xMap x map
yMap y map
canvasRect Contents rect 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, intfrom, intto) const [protected] Draw sticks
Parameters:
painter Painter
xMap x map
yMap y map
canvasRect Contents rect 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, intfrom, intto) const [protected, virtual] Draw symbols
Parameters:
painter Painter
symbol Curve symbol
xMap x map
yMap y map
canvasRect Contents rect 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 rect of the canvas
polygon Polygon - will be modified !
See also:
setBrush(), setBaseline(), setStyle()
void QwtPlotCurve::init () [protected]
Initialize internal members.
double QwtPlotCurve::maxXValue () const [inline]
boundingRect().right()
double QwtPlotCurve::maxYValue () const [inline]
boundingRect().bottom()
double QwtPlotCurve::minXValue () const [inline]
boundingRect().left()
double QwtPlotCurve::minYValue () const [inline]
boundingRect().top()
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 (doublevalue)
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 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().
The default value is 0.0.
Parameters:
value Value of the baseline
See also:
baseline(), setBrush(), setStyle(), setStyle()
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 (CurveAttributeattribute, boolon = 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 (LegendAttributeattribute, boolon = true) Specify an attribute how to
draw the legend identifier
Parameters:
attribute Attribute
on On/Off /sa testLegendAttribute()
void QwtPlotCurve::setPaintAttribute (PaintAttributeattribute, boolon = true) Specify an attribute how to
draw the curve
Parameters:
attribute Paint attribute
on On/Off
See also:
testPaintAttribute()
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, intsize)
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 QVector< QPointF > &samples) Initialize data with an array of points
(explicitly shared).
Parameters:
samples Vector of points
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 double *xData, const double *yData, intsize) 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::setStyle (CurveStylestyle) Set the curve's drawing style
Parameters:
style Curve style
See also:
style()
void QwtPlotCurve::setSymbol (const QwtSymbol *symbol) Assign a symbol
Parameters:
symbol Symbol
See also:
symbol()
QwtPlotCurve::CurveStyle QwtPlotCurve::style () const Return the current style
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 (CurveAttributeattribute) const Returns:
true, if attribute is enabled
See also:
setCurveAttribute()
bool QwtPlotCurve::testLegendAttribute (LegendAttributeattribute) const
Return the current paint attributes. See also:
setLegendAttribute()
bool QwtPlotCurve::testPaintAttribute (PaintAttributeattribute) const
Return the current paint attributes. See also:
setPaintAttribute()
void QwtPlotCurve::updateLegend (QwtLegend *legend) const [virtual]
Update the widget that represents the item on the legend. Parameters:
legend Legend
See also:
drawLegendIdentifier(), legendItem(), QwtPlotItem::Legend
Reimplemented from QwtPlotItem.
Author
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