Qwt User's Guide  6.1.0
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QwtPlotSpectrogram Class Reference

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

#include <qwt_plot_spectrogram.h>

Inheritance diagram for QwtPlotSpectrogram:
Inheritance graph
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Public Types

enum  DisplayMode { ImageMode = 0x01, ContourMode = 0x02 }
 
typedef QFlags< DisplayModeDisplayModes
 Display modes.
 
- Public Types inherited from QwtPlotRasterItem
enum  CachePolicy { NoCache, PaintCache }
 Cache policy The default policy is NoCache. More...
 
enum  PaintAttribute { PaintInDeviceResolution = 1 }
 
typedef QFlags< PaintAttributePaintAttributes
 Paint attributes.
 
- Public Types inherited from QwtPlotItem
enum  RttiValues {
  Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend,
  Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve,
  Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotTradingCurve,
  Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel,
  Rtti_PlotZone, Rtti_PlotUserItem = 1000
}
 Runtime type information. More...
 
enum  ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
 Plot Item Attributes. More...
 
enum  ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
 Plot Item Interests. More...
 
enum  RenderHint { RenderAntialiased = 0x1 }
 Render hints. More...
 
typedef QFlags< ItemAttributeItemAttributes
 Plot Item Attributes.
 
typedef QFlags< ItemInterestItemInterests
 Plot Item Interests.
 
typedef QFlags< RenderHintRenderHints
 Render hints.
 

Public Member Functions

 QwtPlotSpectrogram (const QString &title=QString::null)
 
virtual ~QwtPlotSpectrogram ()
 Destructor.
 
void setDisplayMode (DisplayMode, bool on=true)
 
bool testDisplayMode (DisplayMode) const
 
void setData (QwtRasterData *data)
 
const QwtRasterDatadata () const
 
QwtRasterDatadata ()
 
void setColorMap (QwtColorMap *)
 
const QwtColorMapcolorMap () const
 
virtual QwtInterval interval (Qt::Axis) const
 
virtual QRectF pixelHint (const QRectF &) const
 Pixel hint. More...
 
void setDefaultContourPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
 
void setDefaultContourPen (const QPen &)
 Set the default pen for the contour lines. More...
 
QPen defaultContourPen () const
 
virtual QPen contourPen (double level) const
 Calculate the pen for a contour line. More...
 
void setConrecFlag (QwtRasterData::ConrecFlag, bool on)
 
bool testConrecFlag (QwtRasterData::ConrecFlag) const
 
void setContourLevels (const QList< double > &)
 
QList< double > contourLevels () const
 
virtual int rtti () const
 
virtual void draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &rect) const
 Draw the spectrogram. More...
 
- Public Member Functions inherited from QwtPlotRasterItem
 QwtPlotRasterItem (const QString &title=QString::null)
 Constructor.
 
 QwtPlotRasterItem (const QwtText &title)
 Constructor.
 
virtual ~QwtPlotRasterItem ()
 Destructor.
 
void setPaintAttribute (PaintAttribute, bool on=true)
 
bool testPaintAttribute (PaintAttribute) const
 
void setAlpha (int alpha)
 Set an alpha value for the raster data. More...
 
int alpha () const
 
void setCachePolicy (CachePolicy)
 
CachePolicy cachePolicy () const
 
void invalidateCache ()
 
virtual QRectF boundingRect () const
 
- Public Member Functions inherited from QwtPlotItem
 QwtPlotItem (const QwtText &title=QwtText())
 
virtual ~QwtPlotItem ()
 Destroy the QwtPlotItem.
 
void attach (QwtPlot *plot)
 Attach the item to a plot. More...
 
void detach ()
 This method detaches a QwtPlotItem from any QwtPlot it has been associated with. More...
 
QwtPlotplot () const
 Return attached plot.
 
void setTitle (const QString &title)
 
void setTitle (const QwtText &title)
 
const QwtTexttitle () const
 
void setItemAttribute (ItemAttribute, bool on=true)
 
bool testItemAttribute (ItemAttribute) const
 
void setItemInterest (ItemInterest, bool on=true)
 
bool testItemInterest (ItemInterest) const
 
void setRenderHint (RenderHint, bool on=true)
 
bool testRenderHint (RenderHint) const
 
void setRenderThreadCount (uint numThreads)
 
uint renderThreadCount () const
 
void setLegendIconSize (const QSize &)
 
QSize legendIconSize () const
 
double z () const
 
void setZ (double z)
 Set the z value. More...
 
void show ()
 Show the item.
 
void hide ()
 Hide the item.
 
virtual void setVisible (bool)
 
bool isVisible () const
 
void setAxes (int xAxis, int yAxis)
 
void setXAxis (int axis)
 
int xAxis () const
 Return xAxis.
 
void setYAxis (int axis)
 
int yAxis () const
 Return yAxis.
 
virtual void itemChanged ()
 
virtual void legendChanged ()
 
virtual void getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasSize, double &left, double &top, double &right, double &bottom) const
 Calculate a hint for the canvas margin. More...
 
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
 Update the item to changes of the axes scale division. More...
 
virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
 Update the item to changes of the legend info. More...
 
QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
 Calculate the bounding scale rectangle of 2 maps. More...
 
QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const
 Calculate the bounding paint rectangle of 2 maps. More...
 
virtual QList< QwtLegendDatalegendData () const
 Return all information, that is needed to represent the item on the legend. More...
 
virtual QwtGraphic legendIcon (int index, const QSizeF &) const
 

Protected Member Functions

virtual QImage renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &area, const QSize &imageSize) const
 Render an image from data and color map. More...
 
virtual QSize contourRasterSize (const QRectF &, const QRect &) const
 Return the raster to be used by the CONREC contour algorithm. More...
 
virtual QwtRasterData::ContourLines renderContourLines (const QRectF &rect, const QSize &raster) const
 
virtual void drawContourLines (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtRasterData::ContourLines &lines) const
 
void renderTile (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &imageRect, QImage *image) const
 Render a tile of an image. More...
 
- Protected Member Functions inherited from QwtPlotRasterItem
virtual QwtScaleMap imageMap (Qt::Orientation, const QwtScaleMap &map, const QRectF &area, const QSize &imageSize, double pixelSize) const
 Calculate a scale map for painting to an image. More...
 
- Protected Member Functions inherited from QwtPlotItem
QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const
 Return a default icon from a brush. More...
 

Detailed Description

A plot item, which displays a spectrogram.

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

On multi-core systems the performance of the image composition can often be improved by dividing the area into tiles - each of them rendered in a different thread ( see QwtPlotItem::setRenderThreadCount() ).

In ContourMode contour lines are painted for the contour levels.

spectrogram3.png
See Also
QwtRasterData, QwtColorMap, QwtPlotItem::setRenderThreadCount()

Member Enumeration Documentation

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

See Also
setDisplayMode(), testDisplayMode()
Enumerator
ImageMode 

The values are mapped to colors using a color map.

ContourMode 

The data is displayed using contour lines.

Constructor & Destructor Documentation

QwtPlotSpectrogram::QwtPlotSpectrogram ( const QString &  title = QString::null)
explicit

Sets the following item attributes:

The z value is initialized by 8.0.

Parameters
titleTitle
See Also
QwtPlotItem::setItemAttribute(), QwtPlotItem::setZ()

Member Function Documentation

const QwtColorMap * QwtPlotSpectrogram::colorMap ( ) const
Returns
Color Map used for mapping the intensity values to colors
See Also
setColorMap()
QList< double > QwtPlotSpectrogram::contourLevels ( ) const
Returns
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
levelContour 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 QRectF &  area,
const QRect &  rect 
) const
protectedvirtual

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

A larger size will improve the precision 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 the resolution depending on pixelSize().

Parameters
areaRectangle, where to calculate the contour lines
rectRectangle 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()
QwtRasterData * QwtPlotSpectrogram::data ( )
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 QRectF &  canvasRect 
) const
virtual

Draw the spectrogram.

Parameters
painterPainter
xMapMaps x-values into pixel coordinates.
yMapMaps y-values into pixel coordinates.
canvasRectContents rectangle 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
protectedvirtual

Paint the contour lines

Parameters
painterPainter
xMapMaps x-values into pixel coordinates.
yMapMaps y-values into pixel coordinates.
contourLinesContour lines
See Also
renderContourLines(), defaultContourPen(), contourPen()
QwtInterval QwtPlotSpectrogram::interval ( Qt::Axis  axis) const
virtual
Returns
Bounding interval for an axis

The default implementation returns the interval of the associated raster data object.

Parameters
axisX, Y, or Z axis
See Also
QwtRasterData::interval()

Reimplemented from QwtPlotRasterItem.

QRectF QwtPlotSpectrogram::pixelHint ( const QRectF &  area) const
virtual

Pixel hint.

The geometry of a pixel is used to calculated the resolution and alignment of the rendered image.

The default implementation returns data()->pixelHint( rect );

Parameters
areaIn most implementations the resolution of the data doesn't depend on the requested area.
Returns
Bounding rectangle of a pixel
See Also
QwtPlotRasterItem::pixelHint(), QwtRasterData::pixelHint(), render(), renderImage()

Reimplemented from QwtPlotRasterItem.

QwtRasterData::ContourLines QwtPlotSpectrogram::renderContourLines ( const QRectF &  rect,
const QSize &  raster 
) const
protectedvirtual

Calculate contour lines

Parameters
rectRectangle, where to calculate the contour lines
rasterRaster, used by the CONREC algorithm
Returns
Calculated contour lines
See Also
contourLevels(), setConrecFlag(), QwtRasterData::contourLines()
QImage QwtPlotSpectrogram::renderImage ( const QwtScaleMap xMap,
const QwtScaleMap yMap,
const QRectF &  area,
const QSize &  imageSize 
) const
protectedvirtual

Render an image from data and color map.

For each pixel of area the value is mapped into a color.

Parameters
xMapX-Scale Map
yMapY-Scale Map
areaRequested area for the image in scale coordinates
imageSizeSize of the requested image
Returns
A QImage::Format_Indexed8 or QImage::Format_ARGB32 depending on the color map.
See Also
QwtRasterData::value(), QwtColorMap::rgb(), QwtColorMap::colorIndex()

Implements QwtPlotRasterItem.

void QwtPlotSpectrogram::renderTile ( const QwtScaleMap xMap,
const QwtScaleMap yMap,
const QRect &  tile,
QImage *  image 
) const
protected

Render a tile of an image.

Rendering in tiles can be used to composite an image in parallel threads.

Parameters
xMapX-Scale Map
yMapY-Scale Map
tileGeometry of the tile in image coordinates
imageImage to be rendered
int QwtPlotSpectrogram::rtti ( ) const
virtual
Returns
QwtPlotItem::Rtti_PlotSpectrogram

Reimplemented from QwtPlotItem.

void QwtPlotSpectrogram::setColorMap ( 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
colorMapColor Map
See Also
colorMap(), QwtScaleWidget::setColorBarEnabled(), QwtScaleWidget::setColorMap()
void QwtPlotSpectrogram::setConrecFlag ( QwtRasterData::ConrecFlag  flag,
bool  on 
)

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

Parameters
flagCONREC flag
onOn/Off
See Also
testConrecFlag(), renderContourLines(), QwtRasterData::contourLines()
void QwtPlotSpectrogram::setContourLevels ( const QList< double > &  levels)

Set the levels of the contour lines

Parameters
levelsValues of the contour levels
See Also
contourLevels(), renderContourLines(), QwtRasterData::contourLines()
Note
contourLevels returns the same levels but sorted.
void QwtPlotSpectrogram::setData ( QwtRasterData data)

Set the data to be displayed

Parameters
dataSpectrogram Data
See Also
data()
void QwtPlotSpectrogram::setDefaultContourPen ( const QColor &  color,
qreal  width = 0.0,
Qt::PenStyle  style = Qt::SolidLine 
)

Build and assign the default pen for the contour lines

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic ( see QPen::isCosmetic() ). This method has been introduced to hide this incompatibility.

Parameters
colorPen color
widthPen width
stylePen style
See Also
pen(), brush()
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
modeDisplay mode
onOn/Off

The default setting enables ImageMode.

See Also
DisplayMode, displayMode()
bool QwtPlotSpectrogram::testConrecFlag ( QwtRasterData::ConrecFlag  flag) const

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

Parameters
flagCONREC flag
Returns
true, is enabled

The default setting enables QwtRasterData::IgnoreAllVerticesOnLevel

See Also
setConrecClag(), renderContourLines(), QwtRasterData::contourLines()
bool QwtPlotSpectrogram::testDisplayMode ( DisplayMode  mode) const

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

Parameters
modeDisplay mode
Returns
true if mode is enabled