QwtPlotBarChart - Man Page

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 Member Functions

QwtPlotBarChart (const QString &title=QString())
QwtPlotBarChart (const QwtText &title)
virtual ~QwtPlotBarChart ()
Destructor.
virtual int rtti () const
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 *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
virtual QRectF boundingRect () const
virtual QwtColumnSymbol * specialSymbol (int sampleIndex, const QPointF &) const
virtual QwtText barTitle (int sampleIndex) const
Return the title of a bar.

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
QList< QwtLegendData > legendData () const
Return all information, that is needed to represent the item on the legend.
QwtGraphic legendIcon (int index, const QSizeF &) const

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()

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()

Constructor & Destructor Documentation

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

Constructor

Parameters

title Title of the curve

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

Constructor

Parameters

title Title of the curve

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

QRectF QwtPlotBarChart::boundingRect () const [virtual]

Returns

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

Reimplemented from QwtPlotSeriesItem.

void QwtPlotBarChart::drawBar (QPainter * painter, int sampleIndex, const QPointF & 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

void QwtPlotBarChart::drawSample (QPainter * painter, const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, const QwtInterval & 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()

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

QList< QwtLegendData > QwtPlotBarChart::legendData () const [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.

QwtGraphic QwtPlotBarChart::legendIcon (int index, const QSizeF & size) const [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.

QwtPlotBarChart::LegendMode QwtPlotBarChart::legendMode () const

Returns

Legend mode

See also

setLegendMode()

int QwtPlotBarChart::rtti () const [virtual]

Returns

QwtPlotItem::Rtti_PlotBarChart

Reimplemented from QwtPlotItem.

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

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

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>

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.

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()

QwtColumnSymbol * QwtPlotBarChart::specialSymbol (int sampleIndex, const QPointF & 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

const QwtColumnSymbol * QwtPlotBarChart::symbol () const

Returns

Current symbol or NULL, when no symbol has been assigned

See also

setSymbol()

Author

Generated automatically by Doxygen for Qwt User's Guide from the source code.

Info

Mon Jun 1 2020 Version 6.1.5 Qwt User's Guide