QwtPlotHistogram - Man Page
QwtPlotHistogram represents a series of samples, where an interval is associated with a value ( $y = f([x1,x2])$ ).
Synopsis
#include <qwt_plot_histogram.h>
Inherits QwtPlotSeriesItem, and QwtSeriesStore< QwtIntervalSample >.
Public Types
enum HistogramStyle { Outline, Columns, Lines, UserStyle = 100 }
Public Member Functions
QwtPlotHistogram (const QString &title=QString())
QwtPlotHistogram (const QwtText &title)
virtual ~QwtPlotHistogram ()
Destructor.
virtual int rtti () const override
void setPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
void setPen (const QPen &)
const QPen & pen () const
void setBrush (const QBrush &)
const QBrush & brush () const
void setSamples (const QVector< QwtIntervalSample > &)
void setSamples (QwtSeriesData< QwtIntervalSample > *)
void setBaseline (double)
Set the value of the baseline.
double baseline () const
void setStyle (HistogramStyle style)
HistogramStyle style () const
void setSymbol (const QwtColumnSymbol *)
Assign a symbol.
const QwtColumnSymbol * symbol () const
virtual void drawSeries (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const override
virtual QRectF boundingRect () const override
virtual QwtGraphic legendIcon (int index, const QSizeF &) const override
Protected Member Functions
virtual QwtColumnRect columnRect (const QwtIntervalSample &, const QwtScaleMap &, const QwtScaleMap &) const
virtual void drawColumn (QPainter *, const QwtColumnRect &, const QwtIntervalSample &) const
void drawColumns (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const
void drawOutline (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const
void drawLines (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const
Detailed Description
QwtPlotHistogram represents a series of samples, where an interval is associated with a value ( $y = f([x1,x2])$ ).
The representation depends on the style() and an optional symbol() that is displayed for each interval.
- Note
The term 'histogram' is used in a different way in the areas of digital image processing and statistics. Wikipedia introduces the terms 'image histogram' and 'color histogram' to avoid confusions. While 'image histograms' can be displayed by a QwtPlotCurve there is no applicable plot item for a 'color histogram' yet.
- See also
QwtPlotBarChart, QwtPlotMultiBarChart
Definition at line 41 of file qwt_plot_histogram.h.
Member Enumeration Documentation
enum QwtPlotHistogram::HistogramStyle
Histogram styles. The default style is QwtPlotHistogram::Columns.
- See also
setStyle(), style(), setSymbol(), symbol(), setBaseline()
Enumerator
- Outline
Draw an outline around the area, that is build by all intervals using the pen() and fill it with the brush(). The outline style requires, that the intervals are in increasing order and not overlapping.
- Columns
Draw a column for each interval. When a symbol() has been set the symbol is used otherwise the column is displayed as plain rectangle using pen() and brush().
- Lines
Draw a simple line using the pen() for each interval.
- UserStyle
Styles >= UserStyle are reserved for derived classes that overload drawSeries() with additional application specific ways to display a histogram.
Definition at line 52 of file qwt_plot_histogram.h.
Constructor & Destructor Documentation
QwtPlotHistogram::QwtPlotHistogram (const QString & title = QString()) [explicit]
Constructor
- Parameters
title Title of the histogram.
Definition at line 74 of file qwt_plot_histogram.cpp.
QwtPlotHistogram::QwtPlotHistogram (const QwtText & title) [explicit]
Constructor
- Parameters
title Title of the histogram.
Definition at line 64 of file qwt_plot_histogram.cpp.
Member Function Documentation
double QwtPlotHistogram::baseline () const
- Returns
Value of the baseline
- See also
setBaseline()
Definition at line 253 of file qwt_plot_histogram.cpp.
QRectF QwtPlotHistogram::boundingRect () const [override], [virtual]
- Returns
Bounding rectangle of all samples. For an empty series the rectangle is invalid.
Reimplemented from QwtPlotSeriesItem.
Definition at line 262 of file qwt_plot_histogram.cpp.
const QBrush & QwtPlotHistogram::brush () const
- Returns
Brush used in a style() depending way.
- See also
setPen(), brush()
Definition at line 189 of file qwt_plot_histogram.cpp.
QwtColumnRect QwtPlotHistogram::columnRect (const QwtIntervalSample & sample, const QwtScaleMap & xMap, const QwtScaleMap & yMap) const [protected], [virtual]
Calculate the area that is covered by a sample
- Parameters
sample Sample
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.- Returns
Rectangle, that is covered by a sample
Definition at line 602 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::drawColumn (QPainter * painter, const QwtColumnRect & rect, const QwtIntervalSample & sample) const [protected], [virtual]
Draw a column for a sample in Columns style().
When a symbol() has been set the symbol is used otherwise the column is displayed as plain rectangle using pen() and brush().
- Parameters
painter Painter
rect Rectangle where to paint the column in paint device coordinates
sample Sample to be displayed- Note
In applications, where different intervals need to be displayed in a different way ( f.e different colors or even using different symbols) it is recommended to overload drawColumn().
Definition at line 653 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::drawColumns (QPainter * painter, const QwtScaleMap & xMap, const QwtScaleMap & yMap, int from, int to) const [protected]
Draw a histogram in Columns style()
- Parameters
painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
from Index of the first sample to be painted
to Index of the last sample to be painted. If to < 0 the histogram will be painted to its last point.- See also
setStyle(), style(), setSymbol(), drawColumn()
Definition at line 461 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::drawLines (QPainter * painter, const QwtScaleMap & xMap, const QwtScaleMap & yMap, int from, int to) const [protected]
Draw a histogram in Lines style()
- Parameters
painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
from Index of the first sample to be painted
to Index of the last sample to be painted. If to < 0 the histogram will be painted to its last point.- See also
setStyle(), style(), setPen()
Definition at line 493 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::drawOutline (QPainter * painter, const QwtScaleMap & xMap, const QwtScaleMap & yMap, int from, int to) const [protected]
Draw a histogram in Outline style()
- Parameters
painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
from Index of the first sample to be painted
to Index of the last sample to be painted. If to < 0 the histogram will be painted to its last point.- See also
setStyle(), style()
- Warning
The outline style requires, that the intervals are in increasing order and not overlapping.
Definition at line 376 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::drawSeries (QPainter * painter, const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, int from, int to) const [override], [virtual]
Draw a subset of the histogram samples
- 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 sample to be painted
to Index of the last sample to be painted. If to < 0 the series will be painted to its last sample.- See also
drawOutline(), drawLines(), drawColumns
Implements QwtPlotSeriesItem.
Definition at line 334 of file qwt_plot_histogram.cpp.
QwtGraphic QwtPlotHistogram::legendIcon (int index, const QSizeF & size) const [override], [virtual]
A plain rectangle without pen using the brush()
- Parameters
index Index of the legend entry ( ignored as there is only one )
size Icon size- Returns
A graphic displaying the icon
- See also
QwtPlotItem::setLegendIconSize(), QwtPlotItem::legendData()
Reimplemented from QwtPlotItem.
Definition at line 688 of file qwt_plot_histogram.cpp.
const QPen & QwtPlotHistogram::pen () const
- Returns
Pen used in a style() depending way.
- See also
setPen(), brush()
Definition at line 163 of file qwt_plot_histogram.cpp.
int QwtPlotHistogram::rtti () const [override], [virtual]
- Returns
QwtPlotItem::Rtti_PlotHistogram
Reimplemented from QwtPlotItem.
Definition at line 290 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::setBaseline (double value)
Set the value of the baseline. Each column representing an QwtIntervalSample is defined by its interval and the interval between baseline and the value of the sample.
The default value of the baseline is 0.0.
- Parameters
value Value of the baseline
- See also
baseline()
Definition at line 240 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::setBrush (const QBrush & brush)
Assign a brush, that is used in a style() depending way.
- Parameters
brush New brush
- See also
pen(), brush()
Definition at line 174 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::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()
Definition at line 137 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::setPen (const QPen & pen)
Assign a pen, that is used in a style() depending way.
- Parameters
pen New pen
- See also
pen(), brush()
Definition at line 148 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::setSamples (const QVector< QwtIntervalSample > & samples)
Initialize data with an array of samples.
- Parameters
samples Vector of points
Definition at line 299 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::setSamples (QwtSeriesData< QwtIntervalSample > * data)
Assign a series of samples
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.
Definition at line 315 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::setStyle (HistogramStyle style)
Set the histogram's drawing style
- Parameters
style Histogram style
- See also
HistogramStyle, style()
Definition at line 104 of file qwt_plot_histogram.cpp.
void QwtPlotHistogram::setSymbol (const QwtColumnSymbol * symbol)
Assign a symbol. In Column style an optional symbol can be assigned, that is responsible for displaying the rectangle that is defined by the interval and the distance between baseline() and value. When no symbol has been defined the area is displayed as plain rectangle using pen() and brush().
- See also
style(), symbol(), drawColumn(), pen(), brush()
- Note
In applications, where different intervals need to be displayed in a different way ( f.e different colors or even using different symbols) it is recommended to overload drawColumn().
Definition at line 208 of file qwt_plot_histogram.cpp.
QwtPlotHistogram::HistogramStyle QwtPlotHistogram::style () const
- Returns
Style of the histogram
- See also
HistogramStyle, setStyle()
Definition at line 119 of file qwt_plot_histogram.cpp.
const QwtColumnSymbol * QwtPlotHistogram::symbol () const
- Returns
Current symbol or NULL, when no symbol has been assigned
- See also
setSymbol()
Definition at line 224 of file qwt_plot_histogram.cpp.
Author
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