QwtPlotBarChart - QwtPlotBarChart displays a series of a values as bars.

NAME

QwtPlotBarChart − QwtPlotBarChart displays a series of a values as bars.

SYNOPSIS

#include <qwt_plot_barchart.h>

Inherits QwtPlotAbstractBarChart, and QwtSeriesStore< QPointF >.

Public Types

enum LegendMode { LegendChartTitle, LegendBarTitles }
Legend modes.

Public Types inherited from QwtPlotAbstractBarChart

enum LayoutPolicy { AutoAdjustSamples, ScaleSamplesToAxes, ScaleSampleToCanvas, FixedSampleSize }
Mode how to calculate the bar width.

Public Types inherited from QwtPlotItem

enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotGraphic, Rtti_PlotTradingCurve, Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotVectorField, Rtti_PlotUserItem = 1000 }
Runtime type information.
enum ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
Plot Item Attributes.
enum ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
Plot Item Interests.
enum RenderHint { RenderAntialiased = 0x1 }
Render hints.
typedef QFlags< ItemAttribute > ItemAttributes
typedef QFlags< ItemInterest > ItemInterests
typedef QFlags< RenderHint > RenderHints

Public Member Functions

QwtPlotBarChart (const QString &title=QString())
QwtPlotBarChart (const QwtText &title)
virtual ˜QwtPlotBarChart ()
Destructor.
virtual int rtti () const override
void setSamples (const QVector< QPointF > &)
void setSamples (const QVector< double > &)
void setSamples (QwtSeriesData< QPointF > *)
void setSymbol (QwtColumnSymbol *)
Assign a symbol.
const QwtColumnSymbol * symbol () const
void setLegendMode (LegendMode)
LegendMode legendMode () 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 QwtColumnSymbol * specialSymbol (int sampleIndex, const QPointF &) const
virtual QwtText barTitle (int sampleIndex) const
Return the title of a bar.

Public Member Functions inherited from QwtPlotAbstractBarChart

QwtPlotAbstractBarChart (const QwtText &title)
virtual ˜QwtPlotAbstractBarChart ()
Destructor.
void setLayoutPolicy (LayoutPolicy)
LayoutPolicy layoutPolicy () const
void setLayoutHint (double)
double layoutHint () const
void setSpacing (int)
Set the spacing.
int spacing () const
void setMargin (int)
Set the margin.
int margin () const
void setBaseline (double)
Set the baseline.
double baseline () const
virtual void getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const override
Calculate a hint for the canvas margin.

Public Member Functions inherited from QwtPlotSeriesItem

QwtPlotSeriesItem (const QString &title=QString())
QwtPlotSeriesItem (const QwtText &title)
virtual ˜QwtPlotSeriesItem ()
Destructor.
void setOrientation (Qt::Orientation)
Qt::Orientation orientation () const
virtual void draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const override
Draw the complete series.
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &) override
Update the item to changes of the axes scale division.

Public Member Functions inherited from QwtPlotItem

QwtPlotItem ()
QwtPlotItem (const QString &title)
QwtPlotItem (const QwtText &title)
virtual ˜QwtPlotItem ()
Destroy the QwtPlotItem.
void attach (QwtPlot *plot)
Attach the item to a plot.
void detach ()
This method detaches a QwtPlotItem from any QwtPlot it has been associated with.
QwtPlot * plot () const
Return attached plot.
void setTitle (const QString &title)
void setTitle (const QwtText &title)
const QwtText & title () const
void setItemAttribute (ItemAttribute, bool on=true)
bool testItemAttribute (ItemAttribute) const
void setItemInterest (ItemInterest, bool on=true)
bool testItemInterest (ItemInterest) const
void setRenderHint (RenderHint, bool on=true)
bool testRenderHint (RenderHint) const
void setRenderThreadCount (uint numThreads)
uint renderThreadCount () const
void setLegendIconSize (const QSize &)
QSize legendIconSize () const
double z () const
void setZ (double z)
Set the z value.
void show ()
Show the item.
void hide ()
Hide the item.
virtual void setVisible (bool)
bool isVisible () const
void setAxes (QwtAxisId xAxis, QwtAxisId yAxis)
void setXAxis (QwtAxisId)
QwtAxisId xAxis () const
Return xAxis.
void setYAxis (QwtAxisId)
QwtAxisId yAxis () const
Return yAxis.
virtual void itemChanged ()
virtual void legendChanged ()
virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
Update the item to changes of the legend info.
QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding scale rectangle of 2 maps.
QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding paint rectangle of 2 maps.

Public Member Functions inherited from QwtAbstractSeriesStore

virtual ˜QwtAbstractSeriesStore ()
Destructor.

Public Member Functions inherited from QwtSeriesStore< QPointF >

QwtSeriesStore ()
Constructor The store contains no series.
˜QwtSeriesStore ()
Destructor.
void setData (QwtSeriesData< QPointF > *series)
QwtSeriesData< QPointF > * data ()
const QwtSeriesData< QPointF > * data () const
QPointF sample (int index) const
virtual size_t dataSize () const override
virtual QRectF dataRect () const override
virtual void setRectOfInterest (const QRectF &rect) override
QwtSeriesData< QPointF > * swapData (QwtSeriesData< QPointF > *series)

Protected Member Functions

virtual void drawSample (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, const QwtInterval &boundingInterval, int index, const QPointF &sample) const
virtual void drawBar (QPainter *, int sampleIndex, const QPointF &sample, const QwtColumnRect &) const
QwtColumnRect columnRect (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, const QwtInterval &boundingInterval, const QPointF &sample) const
QList< QwtLegendData > legendData () const override
Return all information, that is needed to represent the item on the legend.
QwtGraphic legendIcon (int index, const QSizeF &) const override

Protected Member Functions inherited from QwtPlotAbstractBarChart

double sampleWidth (const QwtScaleMap &map, double canvasSize, double boundingSize, double value) const

Protected Member Functions inherited from QwtPlotSeriesItem

virtual void dataChanged () override
dataChanged() indicates, that the series has been changed.

Protected Member Functions inherited from QwtPlotItem

QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const
Return a default icon from a brush.

Detailed Description

QwtPlotBarChart displays a series of a values as bars.

Each bar might be customized individually by implementing a specialSymbol(). Otherwise it is rendered using a default symbol.

Depending on its orientation() the bars are displayed horizontally or vertically. The bars cover the interval between the baseline() and the value.

By activating the LegendBarTitles mode each sample will have its own entry on the legend.

The most common use case of a bar chart is to display a list of y coordinates, where the x coordinate is simply the index in the list. But for other situations ( f.e. when values are related to dates ) it is also possible to set x coordinates explicitly.

See also

QwtPlotMultiBarChart, QwtPlotHistogram, QwtPlotCurve::Sticks, QwtPlotSeriesItem::orientation(), QwtPlotAbstractBarChart::baseline()

Definition at line 41 of file qwt_plot_barchart.h.

Member Enumeration Documentation

enum QwtPlotBarChart::LegendMode

Legend modes. The default setting is QwtPlotBarChart::LegendChartTitle.

See also

setLegendMode(), legendMode()

Enumerator
LegendChartTitle

One entry on the legend showing the default symbol and the title() of the chart

See also

QwtPlotItem::title()

LegendBarTitles

One entry for each value showing the individual symbol of the corresponding bar and the bar title.

See also

specialSymbol(), barTitle()

Definition at line 52 of file qwt_plot_barchart.h.

Constructor & Destructor Documentation

QwtPlotBarChart::QwtPlotBarChart (const QString & title = QString())[explicit]

Constructor

Parameters

title Title of the curve

Definition at line 51 of file qwt_plot_barchart.cpp.

QwtPlotBarChart::QwtPlotBarChart (const QwtText & title) [explicit]

Constructor

Parameters

title Title of the curve

Definition at line 41 of file qwt_plot_barchart.cpp.

QwtPlotBarChart::˜QwtPlotBarChart () [virtual]

Destructor.

Definition at line 58 of file qwt_plot_barchart.cpp.

Member Function Documentation

QwtText QwtPlotBarChart::barTitle (int sampleIndex) const [virtual]

Return the title of a bar. In LegendBarTitles mode the title is displayed on the legend entry corresponding to a bar.

The default implementation is a dummy, that is intended to be overloaded.

Parameters

sampleIndex Index of the bar

Returns

An empty text

See also

LegendBarTitles

Definition at line 399 of file qwt_plot_barchart.cpp.

QRectF QwtPlotBarChart::boundingRect () const [override], [virtual]

Returns

Bounding rectangle of all samples. For an empty series the rectangle is invalid.

Reimplemented from QwtPlotSeriesItem.

Definition at line 186 of file qwt_plot_barchart.cpp.

QwtColumnRect QwtPlotBarChart::columnRect (const QwtScaleMap & xMap, constQwtScaleMap & yMap, const QRectF & canvasRect, const QwtInterval &boundingInterval, const QPointF & sample) const [protected]

Calculate the geometry of a bar in widget coordinates

Parameters

xMap x map
yMap y map
canvasRect Contents rect of the canvas
boundingInterval Bounding interval of sample values
sample Value of the sample

Returns

Geometry of the column

Definition at line 262 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::drawBar (QPainter * painter, int sampleIndex, constQPointF & sample, const QwtColumnRect & rect) const [protected],[virtual]

Draw a bar

Parameters

painter Painter
sampleIndex Index of the sample represented by the bar
sample Value of the sample
rect Bounding rectangle of the bar

Definition at line 341 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::drawSample (QPainter * painter, const QwtScaleMap &xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, constQwtInterval & boundingInterval, int index, const QPointF & sample)const [protected], [virtual]

Draw a sample

Parameters

painter Painter
xMap x map
yMap y map
canvasRect Contents rect of the canvas
boundingInterval Bounding interval of sample values
index Index of the sample
sample Value of the sample

See also

drawSeries()

Definition at line 322 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::drawSeries (QPainter * painter, const QwtScaleMap &xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, int from,int to) const [override], [virtual]

Draw an interval of the bar chart

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

drawSymbols()

Implements QwtPlotSeriesItem.

Definition at line 223 of file qwt_plot_barchart.cpp.

QList< QwtLegendData > QwtPlotBarChart::legendData () const [override],[protected], [virtual]

Return all information, that is needed to represent the item on the legend. In case of LegendBarTitles an entry for each bar is returned, otherwise the chart is represented like any other plot item from its title() and the legendIcon().

Returns

Information, that is needed to represent the item on the legend

See also

title(), setLegendMode(), barTitle(), QwtLegend, QwtPlotLegendItem

Reimplemented from QwtPlotItem.

Definition at line 416 of file qwt_plot_barchart.cpp.

QwtGraphic QwtPlotBarChart::legendIcon (int index, const QSizeF & size)const [override], [protected], [virtual]

Returns

Icon representing a bar or the chart on the legend

When the legendMode() is LegendBarTitles the icon shows the bar corresponding to index - otherwise the bar displays the default symbol.

Parameters

index Index of the legend entry
size Icon size

See also

setLegendMode(), drawBar(), QwtPlotItem::setLegendIconSize(), QwtPlotItem::legendData()

Reimplemented from QwtPlotItem.

Definition at line 462 of file qwt_plot_barchart.cpp.

QwtPlotBarChart::LegendMode QwtPlotBarChart::legendMode () const

Returns

Legend mode

See also

setLegendMode()

Definition at line 177 of file qwt_plot_barchart.cpp.

int QwtPlotBarChart::rtti () const [override], [virtual]

Returns

QwtPlotItem::Rtti_PlotBarChart

Reimplemented from QwtPlotItem.

Definition at line 70 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::setLegendMode (LegendMode mode)

Set the mode that decides what to display on the legend

In case of LegendBarTitles barTitle() needs to be overloaded to return individual titles for each bar.

Parameters

mode New mode

See also

legendMode(), legendData(), barTitle(), QwtPlotItem::ItemAttribute

Definition at line 164 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::setSamples (const QVector< double > & samples)

Initialize data with an array of doubles

The indices in the array are taken as x coordinate, while the doubles are interpreted as y values.

Parameters

samples Vector of y coordinates

Note

QVector is implicitly shared

Definition at line 97 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::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>

Definition at line 82 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::setSamples (QwtSeriesData< QPointF > * 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 119 of file qwt_plot_barchart.cpp.

void QwtPlotBarChart::setSymbol (QwtColumnSymbol * symbol)

Assign a symbol. The bar chart 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()

Definition at line 134 of file qwt_plot_barchart.cpp.

QwtColumnSymbol * QwtPlotBarChart::specialSymbol (int sampleIndex, constQPointF & sample) const [virtual]

Needs to be overloaded to return a non default symbol for a specific sample

Parameters

sampleIndex Index of the sample represented by the bar
sample Value of the sample

Returns

NULL, indicating to use the default symbol

Definition at line 377 of file qwt_plot_barchart.cpp.

const QwtColumnSymbol * QwtPlotBarChart::symbol () const

Returns

Current symbol or NULL, when no symbol has been assigned

See also

setSymbol()

Definition at line 150 of file qwt_plot_barchart.cpp.

Author

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Updated 2026-06-01 - jenkler.se | uex.se