Provided by: libqwt-doc_6.1.4-2_all 
NAME
QwtPlotCurve - A plot item, that represents a series of points.
SYNOPSIS
#include <qwt_plot_curve.h>
Inherits QwtPlotSeriesItem, and QwtSeriesStore< 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, 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())
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.
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)
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.
const QBrush & brush () const
void setBaseline (double)
Set the value of the baseline.
double baseline () const
void setStyle (CurveStyle style)
CurveStyle style () const
void setSymbol (QwtSymbol *)
Assign a symbol.
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
Protected Member Functions
void init ()
Initialize internal members.
virtual void drawCurve (QPainter *, 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.
virtual void drawSymbols (QPainter *, const QwtSymbol &, const QwtScaleMap &xMap, const
QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual void drawLines (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap,
const QRectF &canvasRect, int from, int to) const
Draw lines.
virtual void drawSticks (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap,
const QRectF &canvasRect, int from, int to) const
virtual void drawDots (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const
QRectF &canvasRect, int from, int to) const
virtual void drawSteps (QPainter *, 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.
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()) [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()
Author
Generated automatically by Doxygen for Qwt User's Guide from the source code.