Qwt User's Guide: QwtPlotSpectrogram Class Reference

# QwtPlotSpectrogram Class Reference

A plot item, which displays a spectrogram. More...

`#include <qwt_plot_spectrogram.h>`

Inheritance diagram for QwtPlotSpectrogram:
[legend]

List of all members.

## Public Types
enum | DisplayMode { ImageMode = 1, ContourMode = 2 }
## Public Member Functions
| QwtPlotSpectrogram (const QString &title=QString::null)
virtual | ~QwtPlotSpectrogram ()
void | setDisplayMode (DisplayMode, bool on=true)
bool | testDisplayMode (DisplayMode) const
void | setData (const QwtRasterData &data)
const QwtRasterData & | data () const
void | setColorMap (const QwtColorMap &)
const QwtColorMap & | colorMap () const
virtual QwtDoubleRect | boundingRect () const
virtual QSize | rasterHint (const QwtDoubleRect &) const
void | setDefaultContourPen (const QPen &)
QPen | defaultContourPen () const
virtual QPen | contourPen (double level) const
void | setConrecAttribute (QwtRasterData::ConrecAttribute, bool on)
bool | testConrecAttribute (QwtRasterData::ConrecAttribute) const
void | setContourLevels (const QwtValueList &)
QwtValueList | contourLevels () const
virtual int | rtti () const
virtual void | draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const
## Protected Member Functions
virtual QImage | renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtDoubleRect &rect) const
virtual QSize | contourRasterSize (const QwtDoubleRect &, const QRect &) const
virtual QwtRasterData::ContourLines | renderContourLines (const QwtDoubleRect &rect, const QSize &raster) const
virtual void | drawContourLines (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtRasterData::ContourLines &lines) const

## Detailed Description

A plot item, which displays a spectrogram.

A spectrogram displays threedimenional data, where the 3rd dimension ( the intensity ) is displayed using colors. The colors are calculated from the values using a color map.

In ContourMode contour lines are painted for the contour levels.

See also:
  QwtRasterData, QwtColorMap

## Member Enumeration Documentation

enum QwtPlotSpectrogram::DisplayMode

The display mode controls how the raster data will be represented.

- ImageMode
  The values are mapped to colors using a color map.
- ContourMode
  The data is displayed using contour lines

When both modes are enabled the contour lines are painted on top of the spectrogram. The default setting enables ImageMode.

See also:
  setDisplayMode(), testDisplayMode()

## Constructor & Destructor Documentation

QwtPlotSpectrogram::QwtPlotSpectrogram | ( | const QString & | title = `QString::null` | ) | `[explicit]`

Sets the following item attributes:

- QwtPlotItem::AutoScale: true
- QwtPlotItem::Legend: false

The z value is initialized by 8.0.

Parameters:

  | title | Title

See also:
  QwtPlotItem::setItemAttribute(), QwtPlotItem::setZ()

QwtPlotSpectrogram::~QwtPlotSpectrogram | ( |  | ) | `[virtual]`

Destructor.

## Member Function Documentation

QwtDoubleRect QwtPlotSpectrogram::boundingRect | ( |  | ) | const`[virtual]`

Returns:
  Bounding rect of the data

See also:
  QwtRasterData::boundingRect()

Reimplemented from QwtPlotItem.

const QwtColorMap & QwtPlotSpectrogram::colorMap | ( |  | ) | const

Returns:
  Color Map used for mapping the intensity values to colors

See also:
  setColorMap()

QwtValueList QwtPlotSpectrogram::contourLevels | ( |  | ) | const

Return the levels of the contour lines.

The levels are sorted in increasing order.

See also:
  contourLevels(), renderContourLines(), QwtRasterData::contourLines()

QPen QwtPlotSpectrogram::contourPen | ( | double | level | ) | const`[virtual]`

Calculate the pen for a contour line.

The color of the pen is the color for level calculated by the color map

Parameters:

  | level | Contour level

Returns:
  Pen for the contour line

Note:
  contourPen is only used if defaultContourPen().style() == Qt::NoPen

See also:
  setDefaultContourPen(), setColorMap(), setContourLevels()

QSize QwtPlotSpectrogram::contourRasterSize | ( | const QwtDoubleRect & | area,
|  | const QRect & | rect |
| ) |  |  | const`[protected, virtual]`

Return the raster to be used by the CONREC contour algorithm.

A larger size will improve the precisision of the CONREC algorithm, but will slow down the time that is needed to calculate the lines.

The default implementation returns rect.size() / 2 bounded to data().rasterHint().

Parameters:

  | area | Rect, where to calculate the contour lines
  | rect | Rect in pixel coordinates, where to paint the contour lines

Returns:
  Raster to be used by the CONREC contour algorithm.

Note:
  The size will be bounded to rect.size().

See also:
  drawContourLines(), QwtRasterData::contourLines()

const QwtRasterData & QwtPlotSpectrogram::data | ( |  | ) | const

Returns:
  Spectrogram data

See also:
  setData()

QPen QwtPlotSpectrogram::defaultContourPen | ( |  | ) | const

Returns:
  Default contour pen

See also:
  setDefaultContourPen()

void QwtPlotSpectrogram::draw | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRect & | canvasRect |
| ) |  |  | const`[virtual]`

Draw the spectrogram.

Parameters:

  | painter | Painter
  | xMap | Maps x-values into pixel coordinates.
  | yMap | Maps y-values into pixel coordinates.
  | canvasRect | Contents rect of the canvas in painter coordinates

See also:
  setDisplayMode(), renderImage(), QwtPlotRasterItem::draw(), drawContourLines()

Reimplemented from QwtPlotRasterItem.

void QwtPlotSpectrogram::drawContourLines | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QwtRasterData::ContourLines & | contourLines |
| ) |  |  | const`[protected, virtual]`

Paint the contour lines

Parameters:

  | painter | Painter
  | xMap | Maps x-values into pixel coordinates.
  | yMap | Maps y-values into pixel coordinates.
  | contourLines | Contour lines

See also:
  renderContourLines(), defaultContourPen(), contourPen()

QSize QwtPlotSpectrogram::rasterHint | ( | const QwtDoubleRect & | rect | ) | const`[virtual]`

Returns the recommended raster for a given rect.

F.e the raster hint is used to limit the resolution of the image that is rendered.

Parameters:

  | rect | Rect for the raster hint

Returns:
  data().rasterHint(rect)

Reimplemented from QwtPlotRasterItem.

QwtRasterData::ContourLines QwtPlotSpectrogram::renderContourLines | ( | const QwtDoubleRect & | rect,
|  | const QSize & | raster |
| ) |  |  | const`[protected, virtual]`

Calculate contour lines

Parameters:

  | rect | Rectangle, where to calculate the contour lines
  | raster | Raster, used by the CONREC algorithm

See also:
  contourLevels(), setConrecAttribute(), QwtRasterData::contourLines()

QImage QwtPlotSpectrogram::renderImage | ( | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QwtDoubleRect & | area |
| ) |  |  | const`[protected, virtual]`

Render an image from the data and color map.

The area is translated into a rect of the paint device. For each pixel of this rect the intensity is mapped into a color.

Parameters:

  | xMap | X-Scale Map
  | yMap | Y-Scale Map
  | area | Area that should be rendered in scale coordinates.

Returns:
  A QImage::Format_Indexed8 or QImage::Format_ARGB32 depending on the color map.

See also:
  QwtRasterData::intensity(), QwtColorMap::rgb(), QwtColorMap::colorIndex()

Implements QwtPlotRasterItem.

int QwtPlotSpectrogram::rtti | ( |  | ) | const`[virtual]`

Returns:
  QwtPlotItem::Rtti_PlotSpectrogram

Reimplemented from QwtPlotItem.

void QwtPlotSpectrogram::setColorMap | ( | const QwtColorMap & | colorMap | ) |

Change the color map

Often it is useful to display the mapping between intensities and colors as an additional plot axis, showing a color bar.

Parameters:

  | colorMap | Color Map

See also:
  colorMap(), QwtScaleWidget::setColorBarEnabled(), QwtScaleWidget::setColorMap()

void QwtPlotSpectrogram::setConrecAttribute | ( | QwtRasterData::ConrecAttribute | attribute,
|  | bool | on |
| ) |  |  |

Modify an attribute of the CONREC algorithm, used to calculate the contour lines.

Parameters:

  | attribute | CONREC attribute
  | on | On/Off

See also:
  testConrecAttribute(), renderContourLines(), QwtRasterData::contourLines()

void QwtPlotSpectrogram::setContourLevels | ( | const QwtValueList & | levels | ) |

Set the levels of the contour lines

Parameters:

  | levels | Values of the contour levels

See also:
  contourLevels(), renderContourLines(), QwtRasterData::contourLines()

Note:
  contourLevels returns the same levels but sorted.

void QwtPlotSpectrogram::setData | ( | const QwtRasterData & | data | ) |

Set the data to be displayed

Parameters:

  | data | Spectrogram Data

See also:
  data()

void QwtPlotSpectrogram::setDefaultContourPen | ( | const QPen & | pen | ) |

Set the default pen for the contour lines.

If the spectrogram has a valid default contour pen a contour line is painted using the default contour pen. Otherwise (pen.style() == Qt::NoPen) the pen is calculated for each contour level using contourPen().

See also:
  defaultContourPen(), contourPen()

void QwtPlotSpectrogram::setDisplayMode | ( | DisplayMode | mode,
|  | bool | on = `true` |
| ) |  |  |

The display mode controls how the raster data will be represented.

Parameters:

  | mode | Display mode
  | on | On/Off

The default setting enables ImageMode.

See also:
  DisplayMode, displayMode()

bool QwtPlotSpectrogram::testConrecAttribute | ( | QwtRasterData::ConrecAttribute | attribute | ) | const

Test an attribute of the CONREC algorithm, used to calculate the contour lines.

Parameters:

  | attribute | CONREC attribute

Returns:
  true, is enabled

See also:
  setConrecAttribute(), renderContourLines(), QwtRasterData::contourLines()

bool QwtPlotSpectrogram::testDisplayMode | ( | DisplayMode | mode | ) | const

The display mode controls how the raster data will be represented.

Parameters:

  | mode | Display mode

Returns:
  true if mode is enabled