QwtPlotHistogram(3) Qwt User's Guide QwtPlotHistogram(3) NAME QwtPlotHistogram - QwtPlotHistogram represents a series of samples, where an interval is associated with a value ( $y = f([x1,x2])$ ). SYNOPSIS #include 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 Generated automatically by Doxygen for Qwt User's Guide from the source code. Version 6.2.0 Sun Jul 18 2021 QwtPlotHistogram(3)