Provided by: libqwt-doc_6.1.2-5_all 
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 Member Functions
QwtPlotBarChart (const QString &title=QString::null)
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 > *series)
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 &point, 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::null) [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 (intsampleIndex) 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, intsampleIndex, 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,
intindex, 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, intfrom, intto) 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 (intindex, 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 (LegendModemode)
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< 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 (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 (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 (intsampleIndex, 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
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