Qwt User's Guide 5.2.2
Public Types | Public Member Functions | Protected Member Functions

QwtPlotSpectrogram Class Reference

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

#include <qwt_plot_spectrogram.h>

Inheritance diagram for QwtPlotSpectrogram:
Inheritance graph
[legend]

List of all members.

Public Types

enum  CachePolicy {
  NoCache,
  PaintCache,
  ScreenCache
}
enum  DisplayMode {
  ImageMode = 1,
  ContourMode = 2
}
enum  ItemAttribute {
  Legend = 1,
  AutoScale = 2
}
enum  RenderHint { RenderAntialiased = 1 }
enum  RttiValues {
  Rtti_PlotItem = 0,
  Rtti_PlotGrid,
  Rtti_PlotScale,
  Rtti_PlotMarker,
  Rtti_PlotCurve,
  Rtti_PlotHistogram,
  Rtti_PlotSpectrogram,
  Rtti_PlotSVG,
  Rtti_PlotUserItem = 1000
}

Public Member Functions

int alpha () const
void attach (QwtPlot *plot)
virtual QwtDoubleRect boundingRect () const
CachePolicy cachePolicy () const
const QwtColorMapcolorMap () const
QwtValueList contourLevels () const
virtual QPen contourPen (double level) const
const QwtRasterDatadata () const
QPen defaultContourPen () const
void detach ()
virtual void draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const
void hide ()
void invalidateCache ()
QwtDoubleRect invTransform (const QwtScaleMap &, const QwtScaleMap &, const QRect &) const
bool isVisible () const
virtual void itemChanged ()
virtual QWidget * legendItem () const
QRect paintRect (const QwtScaleMap &, const QwtScaleMap &) const
QwtPlotplot () const
 QwtPlotSpectrogram (const QString &title=QString::null)
virtual QSize rasterHint (const QwtDoubleRect &) const
virtual int rtti () const
QwtDoubleRect scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
void setAlpha (int alpha)
void setAxis (int xAxis, int yAxis)
void setCachePolicy (CachePolicy)
void setColorMap (const QwtColorMap &)
void setConrecAttribute (QwtRasterData::ConrecAttribute, bool on)
void setContourLevels (const QwtValueList &)
void setData (const QwtRasterData &data)
void setDefaultContourPen (const QPen &)
void setDisplayMode (DisplayMode, bool on=true)
void setItemAttribute (ItemAttribute, bool on=true)
void setRenderHint (RenderHint, bool on=true)
void setTitle (const QwtText &title)
void setTitle (const QString &title)
virtual void setVisible (bool)
void setXAxis (int axis)
void setYAxis (int axis)
void setZ (double z)
void show ()
bool testConrecAttribute (QwtRasterData::ConrecAttribute) const
bool testDisplayMode (DisplayMode) const
bool testItemAttribute (ItemAttribute) const
bool testRenderHint (RenderHint) const
const QwtTexttitle () const
QRect transform (const QwtScaleMap &, const QwtScaleMap &, const QwtDoubleRect &) const
virtual void updateLegend (QwtLegend *) const
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
int xAxis () const
int yAxis () const
double z () const
virtual ~QwtPlotSpectrogram ()

Protected Member Functions

virtual QSize contourRasterSize (const QwtDoubleRect &, const QRect &) const
virtual void drawContourLines (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtRasterData::ContourLines &lines) const
virtual QwtRasterData::ContourLines renderContourLines (const QwtDoubleRect &rect, const QSize &raster) const
virtual QImage renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtDoubleRect &rect) 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.

spectrogram3.png
See also:
QwtRasterData, QwtColorMap

Member Enumeration Documentation

  • NoCache
    renderImage() is called, whenever the item has to be repainted
  • PaintCache
    renderImage() is called, whenever the image cache is not valid, or the scales, or the size of the canvas has changed. This type of cache is only useful for improving the performance of hide/show operations. All other situations are already handled by the plot canvas cache.
  • ScreenCache
    The screen cache is an image in size of the screen. As long as the scales don't change the target image is scaled from the cache. This might improve the performance when resizing the plot widget, but suffers from scaling effects.

The default policy is NoCache

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()
enum QwtPlotItem::ItemAttribute [inherited]

Plot Item Attributes

  • Legend
    The item is represented on the legend.
  • AutoScale
    The boundingRect() of the item is included in the autoscaling calculation.
See also:
setItemAttribute(), testItemAttribute()
enum QwtPlotItem::RenderHint [inherited]

Render hints.

enum QwtPlotItem::RttiValues [inherited]

Runtime type information.

RttiValues is used to cast plot items, without having to enable runtime type information of the compiler.


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:
titleTitle
See also:
QwtPlotItem::setItemAttribute(), QwtPlotItem::setZ()
QwtPlotSpectrogram::~QwtPlotSpectrogram ( ) [virtual]

Destructor.


Member Function Documentation

int QwtPlotRasterItem::alpha ( ) const [inherited]
Returns:
Alpha value of the raster item
See also:
setAlpha()
void QwtPlotItem::attach ( QwtPlot plot) [inherited]

Attach the item to a plot.

This method will attach a QwtPlotItem to the QwtPlot argument. It will first detach the QwtPlotItem from any plot from a previous call to attach (if necessary). If a NULL argument is passed, it will detach from any QwtPlot it was attached to.

Parameters:
plotPlot widget
See also:
QwtPlotItem::detach()
QwtDoubleRect QwtPlotSpectrogram::boundingRect ( ) const [virtual]
Returns:
Bounding rect of the data
See also:
QwtRasterData::boundingRect()

Reimplemented from QwtPlotItem.

QwtPlotRasterItem::CachePolicy QwtPlotRasterItem::cachePolicy ( ) const [inherited]
Returns:
Cache policy
See also:
CachePolicy, setCachePolicy()
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:
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 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:
areaRect, where to calculate the contour lines
rectRect 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 QwtPlotItem::detach ( ) [inline, inherited]

This method detaches a QwtPlotItem from any QwtPlot it has been associated with.

detach() is equivalent to calling attach( NULL )

See also:
attach( QwtPlot* plot )
void QwtPlotSpectrogram::draw ( QPainter *  painter,
const QwtScaleMap xMap,
const QwtScaleMap yMap,
const QRect &  canvasRect 
) const [virtual]

Draw the spectrogram.

Parameters:
painterPainter
xMapMaps x-values into pixel coordinates.
yMapMaps y-values into pixel coordinates.
canvasRectContents 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:
painterPainter
xMapMaps x-values into pixel coordinates.
yMapMaps y-values into pixel coordinates.
contourLinesContour lines
See also:
renderContourLines(), defaultContourPen(), contourPen()
void QwtPlotItem::hide ( ) [inherited]

Hide the item.

void QwtPlotRasterItem::invalidateCache ( ) [inherited]

Invalidate the paint cache

See also:
setCachePolicy()
QwtDoubleRect QwtPlotItem::invTransform ( const QwtScaleMap xMap,
const QwtScaleMap yMap,
const QRect &  rect 
) const [inherited]

Transform a rectangle from paint to scale coordinates

Parameters:
xMapX map
yMapY map
rectRectangle in paint coordinates
Returns:
Rectangle in scale coordinates
See also:
transform()
bool QwtPlotItem::isVisible ( ) const [inherited]
Returns:
true if visible
See also:
setVisible(), show(), hide()
void QwtPlotItem::itemChanged ( ) [virtual, inherited]

Update the legend and call QwtPlot::autoRefresh for the parent plot.

See also:
updateLegend()
QWidget * QwtPlotItem::legendItem ( ) const [virtual, inherited]

Allocate the widget that represents the item on the legend.

The default implementation is made for QwtPlotCurve and returns a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend().

Returns:
QwtLegendItem()
See also:
updateLegend() QwtLegend()

Implements QwtLegendItemManager.

QRect QwtPlotItem::paintRect ( const QwtScaleMap xMap,
const QwtScaleMap yMap 
) const [inherited]

Calculate the bounding paint rect of 2 maps.

Parameters:
xMapX map
yMapX map
Returns:
Bounding rect of the scale maps
QwtPlot * QwtPlotItem::plot ( ) const [inherited]

Return attached plot.

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:
rectRect 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:
rectRectangle, where to calculate the contour lines
rasterRaster, 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:
xMapX-Scale Map
yMapY-Scale Map
areaArea 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.

QwtDoubleRect QwtPlotItem::scaleRect ( const QwtScaleMap xMap,
const QwtScaleMap yMap 
) const [inherited]

Calculate the bounding scale rect of 2 maps.

Parameters:
xMapX map
yMapX map
Returns:
Bounding rect of the scale maps
void QwtPlotRasterItem::setAlpha ( int  alpha) [inherited]

Set an alpha value for the raster data.

Often a plot has several types of raster data organized in layers. ( f.e a geographical map, with weather statistics ). Using setAlpha() raster items can be stacked easily.

The alpha value is a value [0, 255] to control the transparency of the image. 0 represents a fully transparent color, while 255 represents a fully opaque color.

Parameters:
alphaAlpha value
  • alpha >= 0
    All alpha values of the pixels returned by renderImage() will be set to alpha, beside those with an alpha value of 0 (invalid pixels).
  • alpha < 0 The alpha values returned by renderImage() are not changed.

The default alpha value is -1.

See also:
alpha()
void QwtPlotItem::setAxis ( int  xAxis,
int  yAxis 
) [inherited]

Set X and Y axis

The item will painted according to the coordinates its Axes.

Parameters:
xAxisX Axis
yAxisY Axis
See also:
setXAxis(), setYAxis(), xAxis(), yAxis()
void QwtPlotRasterItem::setCachePolicy ( QwtPlotRasterItem::CachePolicy  policy) [inherited]

Change the cache policy

The default policy is NoCache

Parameters:
policyCache policy
See also:
CachePolicy, cachePolicy()
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:
colorMapColor 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:
attributeCONREC attribute
onOn/Off
See also:
testConrecAttribute(), renderContourLines(), QwtRasterData::contourLines()
void QwtPlotSpectrogram::setContourLevels ( const QwtValueList &  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 ( const QwtRasterData data)

Set the data to be displayed

Parameters:
dataSpectrogram 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:
modeDisplay mode
onOn/Off

The default setting enables ImageMode.

See also:
DisplayMode, displayMode()
void QwtPlotItem::setItemAttribute ( ItemAttribute  attribute,
bool  on = true 
) [inherited]

Toggle an item attribute

Parameters:
attributeAttribute type
ontrue/false
See also:
testItemAttribute(), ItemAttribute
void QwtPlotItem::setRenderHint ( RenderHint  hint,
bool  on = true 
) [inherited]

Toggle an render hint

Parameters:
hintRender hint
ontrue/false
See also:
testRenderHint(), RenderHint
void QwtPlotItem::setTitle ( const QwtText title) [inherited]

Set a new title

Parameters:
titleTitle
See also:
title()
void QwtPlotItem::setTitle ( const QString &  title) [inherited]

Set a new title

Parameters:
titleTitle
See also:
title()
void QwtPlotItem::setVisible ( bool  on) [virtual, inherited]

Show/Hide the item

Parameters:
onShow if true, otherwise hide
See also:
isVisible(), show(), hide()
void QwtPlotItem::setXAxis ( int  axis) [inherited]

Set the X axis

The item will painted according to the coordinates its Axes.

Parameters:
axisX Axis
See also:
setAxis(), setYAxis(), xAxis()
void QwtPlotItem::setYAxis ( int  axis) [inherited]

Set the Y axis

The item will painted according to the coordinates its Axes.

Parameters:
axisY Axis
See also:
setAxis(), setXAxis(), yAxis()
void QwtPlotItem::setZ ( double  z) [inherited]

Set the z value.

Plot items are painted in increasing z-order.

Parameters:
zZ-value
See also:
z(), QwtPlotDict::itemList()
void QwtPlotItem::show ( ) [inherited]

Show the item.

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

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

Parameters:
attributeCONREC 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:
modeDisplay mode
Returns:
true if mode is enabled
bool QwtPlotItem::testItemAttribute ( ItemAttribute  attribute) const [inherited]

Test an item attribute

Parameters:
attributeAttribute type
Returns:
true/false
See also:
setItemAttribute(), ItemAttribute
bool QwtPlotItem::testRenderHint ( RenderHint  hint) const [inherited]

Test a render hint

Parameters:
hintRender hint
Returns:
true/false
See also:
setRenderHint(), RenderHint
const QwtText & QwtPlotItem::title ( ) const [inherited]
Returns:
Title of the item
See also:
setTitle()
QRect QwtPlotItem::transform ( const QwtScaleMap xMap,
const QwtScaleMap yMap,
const QwtDoubleRect &  rect 
) const [inherited]

Transform a rectangle

Parameters:
xMapX map
yMapY map
rectRectangle in scale coordinates
Returns:
Rectangle in paint coordinates
See also:
invTransform()
void QwtPlotItem::updateLegend ( QwtLegend legend) const [virtual, inherited]

Update the widget that represents the item on the legend.

updateLegend() is called from itemChanged() to adopt the widget representing the item on the legend to its new configuration.

The default implementation is made for QwtPlotCurve and updates a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend().

Parameters:
legendLegend
See also:
legendItem(), itemChanged(), QwtLegend()

Implements QwtLegendItemManager.

Reimplemented in QwtPlotCurve.

void QwtPlotItem::updateScaleDiv ( const QwtScaleDiv ,
const QwtScaleDiv  
) [virtual, inherited]

Update the item to changes of the axes scale division.

Update the item, when the axes of plot have changed. The default implementation does nothing, but items that depend on the scale division (like QwtPlotGrid()) have to reimplement updateScaleDiv()

Parameters:
xScaleDivScale division of the x-axis
yScaleDivScale division of the y-axis
See also:
QwtPlot::updateAxes()

Reimplemented in QwtPlotGrid, and QwtPlotScaleItem.

int QwtPlotItem::xAxis ( ) const [inherited]

Return xAxis.

int QwtPlotItem::yAxis ( ) const [inherited]

Return yAxis.

double QwtPlotItem::z ( ) const [inherited]

Plot items are painted in increasing z-order.

Returns:
setZ(), QwtPlotDict::itemList()