NAME

       QwtPlotAbstractBarChart -

       Abstract base class for bar chart items.

SYNOPSIS

       #include <qwt_plot_abstract_barchart.h>

       Inherits QwtPlotSeriesItem.

       Inherited by QwtPlotBarChart, and QwtPlotMultiBarChart.

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

   Public Member Functions
       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
           Calculate a hint for the canvas margin.

   Protected Member Functions
       double sampleWidth (const QwtScaleMap &map, double canvasSize, double dataSize, double
           value) const

Detailed Description

       Abstract base class for bar chart items.

       In opposite to almost all other plot items bar charts can't be displayed inside of their
       bounding rectangle and need a special API how to calculate the width of the bars and how
       they affect the layout of the attached plot.

Member Enumeration Documentation

   enum QwtPlotAbstractBarChart::LayoutPolicy
       Mode how to calculate the bar width. setLayoutPolicy(), setLayoutHint(), barWidthHint()

       Enumerator

       AutoAdjustSamples
              The sample width is calculated by dividing the bounding rectangle by the number of
              samples. The layoutHint() is used as a minimum width in paint device coordinates.

       See Also:
           boundingRectangle()

       ScaleSamplesToAxes
              layoutHint() defines an interval in axis coordinates

       ScaleSampleToCanvas
              The bar width is calculated by multiplying layoutHint() with the height or width of
              the canvas.

       See Also:
           boundingRectangle()

       FixedSampleSize
              layoutHint() defines a fixed width in paint device coordinates.

Constructor & Destructor Documentation

   QwtPlotAbstractBarChart::QwtPlotAbstractBarChart (const QwtText &title) [explicit]
       Constructor

       Parameters:
           title Title of the chart

Member Function Documentation

   double QwtPlotAbstractBarChart::baseline () const
       Returns:
           Value for the origin of the bar chart

       See Also:
           setBaseline(), QwtPlotSeriesItem::orientation()

   void QwtPlotAbstractBarChart::getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap
       &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom)
       const [virtual]
       Calculate a hint for the canvas margin. Bar charts need to reserve some space for
       displaying the bars for the first and the last sample. The hint is calculated from the
       layoutHint() depending on the layoutPolicy().

       The margins are in target device coordinates ( pixels on screen )

       Parameters:
           xMap Maps x-values into pixel coordinates.
           yMap Maps y-values into pixel coordinates.
           canvasRect Contents rectangle of the canvas in painter coordinates
           left Returns the left margin
           top Returns the top margin
           right Returns the right margin
           bottom Returns the bottom margin

       Returns:
           Margin

       See Also:
           layoutPolicy(), layoutHint(), QwtPlotItem::Margins QwtPlot::getCanvasMarginsHint(),
           QwtPlot::updateCanvasMargins()

       Reimplemented from QwtPlotItem.

   double QwtPlotAbstractBarChart::layoutHint () const
       The combination of layoutPolicy() and layoutHint() define how the width of the bars is
       calculated

       Returns:
           Layout policy of the chart item

       See Also:
           LayoutPolicy, setLayoutHint(), layoutPolicy()

   QwtPlotAbstractBarChart::LayoutPolicy QwtPlotAbstractBarChart::layoutPolicy () const
       The combination of layoutPolicy() and layoutHint() define how the width of the bars is
       calculated

       Returns:
           Layout policy of the chart item

       See Also:
           setLayoutPolicy(), layoutHint()

   int QwtPlotAbstractBarChart::margin () const
       Returns:
           Margin between the outmost bars and the contentsRect() of the canvas.

       See Also:
           setMargin(), spacing()

   double QwtPlotAbstractBarChart::sampleWidth (const QwtScaleMap &map, doublecanvasSize,
       doubleboundingSize, doublevalue) const [protected]
       Calculate the width for a sample in paint device coordinates

       Parameters:
           map Scale map for the corresponding scale
           canvasSize Size of the canvas in paint device coordinates
           boundingSize Bounding size of the chart in plot coordinates ( used in
           AutoAdjustSamples mode )
           value Value of the sample

       Returns:
           Sample width

       See Also:
           layoutPolicy(), layoutHint()

   void QwtPlotAbstractBarChart::setBaseline (doublevalue)
       Set the baseline. The baseline is the origin for the chart. Each bar is painted from the
       baseline in the direction of the sample value. In case of a horizontal orientation() the
       baseline is interpreted as x - otherwise as y - value.

       The default value for the baseline is 0.

       Parameters:
           value Value for the baseline

       See Also:
           baseline(), QwtPlotSeriesItem::orientation()

   void QwtPlotAbstractBarChart::setLayoutHint (doublehint)
       The combination of layoutPolicy() and layoutHint() define how the width of the bars is
       calculated

       Parameters:
           hint Layout hint

       See Also:
           LayoutPolicy, layoutPolicy(), layoutHint()

   void QwtPlotAbstractBarChart::setLayoutPolicy (LayoutPolicypolicy)
       The combination of layoutPolicy() and layoutHint() define how the width of the bars is
       calculated

       Parameters:
           policy Layout policy

       See Also:
           layoutPolicy(), layoutHint()

   void QwtPlotAbstractBarChart::setMargin (intmargin)
       Set the margin. The margin is the distance between the outmost bars and the contentsRect()
       of the canvas. The default setting is 5 pixels.

       Parameters:
           margin Margin

       See Also:
           spacing(), margin()

   void QwtPlotAbstractBarChart::setSpacing (intspacing)
       Set the spacing. The spacing is the distance between 2 samples ( bars for QwtPlotBarChart
       or a group of bars for QwtPlotMultiBarChart ) in paint device coordinates.

       See Also:
           spacing()

   int QwtPlotAbstractBarChart::spacing () const
       Returns:
           Spacing between 2 samples ( bars or groups of bars )

       See Also:
           setSpacing(), margin()

Author

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