QwtPlotBarChart(3)

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())
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< 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 (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

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