Qwt User's Guide 6.0.2

- Main Page
- Related Pages
- Classes

- Class List
- Class Index
- Class Hierarchy
- Class Members

Public Types | Public Member Functions | Protected Member Functions
QwtPlotHistogram Class Reference

`#include <qwt_plot_histogram.h>`

Inheritance diagram for QwtPlotHistogram:
[legend]

List of all members.

## Public Types

enum | HistogramStyle { Outline, Columns, Lines, UserStyle = 100 }

## Public Member Functions

| QwtPlotHistogram (const QString &title=QString::null)
| QwtPlotHistogram (const QwtText &title)
virtual | ~QwtPlotHistogram ()
double | baseline () const
virtual QRectF | boundingRect () const
const QBrush & | brush () const
virtual void | drawLegendIdentifier (QPainter *, const QRectF &) const
virtual void | drawSeries (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
const QPen & | pen () const
virtual int | rtti () const
void | setBaseline (double reference)
void | setBrush (const QBrush &)
void | setPen (const QPen &)
void | setSamples (const QVector< QwtIntervalSample > &)
void | setStyle (HistogramStyle style)
void | setSymbol (const QwtColumnSymbol *)
HistogramStyle | style () const
const QwtColumnSymbol * | symbol () const
Public Member Functions inherited from QwtPlotSeriesItem< QwtIntervalSample >
| QwtPlotSeriesItem (const QString &title=QString::null)
| QwtPlotSeriesItem (const QwtText &title)
virtual | ~QwtPlotSeriesItem ()
QwtSeriesData < QwtIntervalSample > * | data ()
const QwtSeriesData < QwtIntervalSample > * | data () const
size_t | dataSize () const
QwtIntervalSample | sample (int index) const
void | setData (QwtSeriesData< QwtIntervalSample > *)
virtual void | updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
Public Member Functions inherited from QwtPlotAbstractSeriesItem
| QwtPlotAbstractSeriesItem (const QString &title=QString::null)
| QwtPlotAbstractSeriesItem (const QwtText &title)
virtual | ~QwtPlotAbstractSeriesItem ()
virtual void | draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &) const
Qt::Orientation | orientation () const
void | setOrientation (Qt::Orientation)
Public Member Functions inherited from QwtPlotItem
| QwtPlotItem (const QwtText &title=QwtText())
virtual | ~QwtPlotItem ()
void | attach (QwtPlot *plot)
void | detach ()
void | hide ()
bool | isVisible () const
virtual void | itemChanged ()
virtual QWidget * | legendItem () const
QRectF | paintRect (const QwtScaleMap &, const QwtScaleMap &) const
QwtPlot * | plot () const
QRectF | scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
void | setAxes (int xAxis, int yAxis)
void | setItemAttribute (ItemAttribute, bool on=true)
void | setRenderHint (RenderHint, bool on=true)
void | setTitle (const QString &title)
void | setTitle (const QwtText &title)
virtual void | setVisible (bool)
void | setXAxis (int axis)
void | setYAxis (int axis)
void | setZ (double z)
void | show ()
bool | testItemAttribute (ItemAttribute) const
bool | testRenderHint (RenderHint) const
const QwtText & | title () const
virtual void | updateLegend (QwtLegend *) const
int | xAxis () const
int | yAxis () const
double | z () const
Public Member Functions inherited from QwtLegendItemManager
| QwtLegendItemManager ()
virtual | ~QwtLegendItemManager ()

## Protected Member Functions

virtual QwtColumnRect | columnRect (const QwtIntervalSample &, const QwtScaleMap &, const QwtScaleMap &) const
virtual void | drawColumn (QPainter *, const QwtColumnRect &, const QwtIntervalSample &) const
void | drawColumns (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const
void | drawLines (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const
void | drawOutline (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, int from, int to) const

## Additional Inherited Members

Protected Attributes inherited from QwtPlotSeriesItem< QwtIntervalSample >
QwtSeriesData < QwtIntervalSample > * | d_series

## Detailed Description

QwtPlotHistogram represents a series of samples, where an interval is associated with a value ( ).

The representation depends on the style() and an optional symbol() that is displayed for each interval.

Note:
  The term "histogram" is used in a different way in the areas of digital image processing and statistics. Wikipedia introduces the terms "image histogram" and "color histogram" to avoid confusions. While "image histograms" can be displayed by a QwtPlotCurve there is no applicable plot item for a "color histogram" yet.

## Member Enumeration Documentation

enum QwtPlotHistogram::HistogramStyle

Histogram styles. The default style is QwtPlotHistogram::Columns.

See also:
  setStyle(), style(), setSymbol(), symbol(), setBaseline()

Enumerator:

  Outline | Draw an outline around the area, that is build by all intervals using the pen() and fill it with the brush(). The outline style requires, that the intervals are in increasing order and not overlapping.
  Columns | Draw a column for each interval. When a symbol() has been set the symbol is used otherwise the column is displayed as plain rectangle using pen() and brush().
  Lines | Draw a simple line using the pen() for each interval.
  UserStyle | Styles >= UserStyle are reserved for derived classes that overload drawSeries() with additional application specific ways to display a histogram.

## Constructor & Destructor Documentation

QwtPlotHistogram::QwtPlotHistogram | ( | const QString & | title = `QString::null` | ) |

explicit

Constructor

Parameters:

  title | Title of the histogram.

QwtPlotHistogram::QwtPlotHistogram | ( | const QwtText & | title | ) |

explicit

Constructor

Parameters:

  title | Title of the histogram.

## Member Function Documentation

double QwtPlotHistogram::baseline | ( |  | ) | const

Returns:
  Value of the baseline

See also:
  setBaseline()

QRectF QwtPlotHistogram::boundingRect | ( |  | ) | const

virtual

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

Reimplemented from QwtPlotSeriesItem< QwtIntervalSample >.

const QBrush & QwtPlotHistogram::brush | ( |  | ) | const

Returns:
  Brush used in a style() depending way.

See also:
  setPen(), brush()

QwtColumnRect QwtPlotHistogram::columnRect | ( | const QwtIntervalSample & | sample,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap
| ) |  | const

protectedvirtual

Calculate the area that is covered by a sample

Parameters:

  sample | Sample
  xMap | Maps x-values into pixel coordinates.
  yMap | Maps y-values into pixel coordinates.

Returns:
  Rectangle, that is covered by a sample

void QwtPlotHistogram::drawColumn | ( | QPainter * | painter,
|  | const QwtColumnRect & | rect,
|  | const QwtIntervalSample & | sample
| ) |  | const

protectedvirtual

Draw a column for a sample in Columns style().

When a symbol() has been set the symbol is used otherwise the column is displayed as plain rectangle using pen() and brush().

Parameters:

  painter | Painter
  rect | Rectangle where to paint the column in paint device coordinates
  sample | Sample to be displayed

Note:
  In applications, where different intervals need to be displayed in a different way ( f.e different colors or even using differnt symbols) it is recommended to overload drawColumn().

void QwtPlotHistogram::drawColumns | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | int | from,
|  | int | to
| ) |  | const

protected

Draw a histogram in Columns style()

Parameters:

  painter | Painter
  xMap | Maps x-values into pixel coordinates.
  yMap | Maps y-values into pixel coordinates.
  from | Index of the first sample to be painted
  to | Index of the last sample to be painted. If to < 0 the histogram will be painted to its last point.

See also:
  setStyle(), style(), setSymbol(), drawColumn()

void QwtPlotHistogram::drawLegendIdentifier | ( | QPainter * | painter,
|  | const QRectF & | rect
| ) |  | const

virtual

Draw a plain rectangle without pen using the brush() as identifier

Parameters:

  painter | Painter
  rect | Bounding rectangle for the identifier

Reimplemented from QwtLegendItemManager.

void QwtPlotHistogram::drawLines | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | int | from,
|  | int | to
| ) |  | const

protected

Draw a histogram in Lines style()

Parameters:

  painter | Painter
  xMap | Maps x-values into pixel coordinates.
  yMap | Maps y-values into pixel coordinates.
  from | Index of the first sample to be painted
  to | Index of the last sample to be painted. If to < 0 the histogram will be painted to its last point.

See also:
  setStyle(), style(), setPen()

void QwtPlotHistogram::drawOutline | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | int | from,
|  | int | to
| ) |  | const

protected

Draw a histogram in Outline style()

Parameters:

  painter | Painter
  xMap | Maps x-values into pixel coordinates.
  yMap | Maps y-values into pixel coordinates.
  from | Index of the first sample to be painted
  to | Index of the last sample to be painted. If to < 0 the histogram will be painted to its last point.

See also:
  setStyle(), style()

Warning:
  The outline style requires, that the intervals are in increasing order and not overlapping.

void QwtPlotHistogram::drawSeries | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect,
|  | int | from,
|  | int | to
| ) |  | const

virtual

Draw a subset of the histogram samples

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 sample to be painted
  to | Index of the last sample to be painted. If to < 0 the series will be painted to its last sample.

See also:
  drawOutline(), drawLines(), drawColumns

Implements QwtPlotAbstractSeriesItem.

const QPen & QwtPlotHistogram::pen | ( |  | ) | const

Returns:
  Pen used in a style() depending way.

See also:
  setPen(), brush()

int QwtPlotHistogram::rtti | ( |  | ) | const

virtual

Returns:
  QwtPlotItem::Rtti_PlotHistogram

Reimplemented from QwtPlotItem.

void QwtPlotHistogram::setBaseline | ( | double | value | ) |

Set the value of the baseline.

Each column representing an QwtIntervalSample is defined by its interval and the interval between baseline and the value of the sample.

The default value of the baseline is 0.0.

Parameters:

  value | Value of the baseline

See also:
  baseline()

void QwtPlotHistogram::setBrush | ( | const QBrush & | brush | ) |

Assign a brush, that is used in a style() depending way.

Parameters:

  brush | New brush

See also:
  pen(), brush()

void QwtPlotHistogram::setPen | ( | const QPen & | pen | ) |

Assign a pen, that is used in a style() depending way.

Parameters:

  pen | New pen

See also:
  pen(), brush()

void QwtPlotHistogram::setSamples | ( | const QVector< QwtIntervalSample > & | samples | ) |

Initialize data with an array of samples.

Parameters:

  samples | Vector of points

void QwtPlotHistogram::setStyle | ( | HistogramStyle | style | ) |

Set the histogram's drawing style

Parameters:

  style | Histogram style

See also:
  HistogramStyle, style()

void QwtPlotHistogram::setSymbol | ( | const QwtColumnSymbol * | symbol | ) |

Assign a symbol.

In Column style an optional symbol can be assigned, that is responsible for displaying the rectangle that is defined by the interval and the distance between baseline() and value. When no symbol has been defined the area is displayed as plain rectangle using pen() and brush().

See also:
  style(), symbol(), drawColumn(), pen(), brush()

Note:
  In applications, where different intervals need to be displayed in a different way ( f.e different colors or even using differnt symbols) it is recommended to overload drawColumn().

QwtPlotHistogram::HistogramStyle QwtPlotHistogram::style | ( |  | ) | const

Return the current style

See also:
  HistogramStyle, setStyle()

const QwtColumnSymbol * QwtPlotHistogram::symbol | ( |  | ) | const

Returns:
  Current symbol or NULL, when no symbol has been assigned

See also:
  setSymbol()