QwtPlotSpectrogram(3)

📦
version 6.3.0 · 6 versions
, in alpine 3.24

💅 QwtPlotSpectrogram(3) — Library Functions Manual 💅

🌸 NAME 🌸

okay so bestie, QwtPlotSpectrogram is a plot item that displays a spectrogram. That's the whole name vibe, no cap 💖

✨ SYNOPSIS ✨

#include <qwt_plot_spectrogram.h>

Inherits QwtPlotRasterItem.

🧬 Public Types 🧬

  • enum DisplayMode { ImageMode = 0x01, ContourMode = 0x02 } — the display-mode enum, iconic.
  • typedef QFlags< DisplayMode > DisplayModes — a flags combo for those display modes.

🎀 Public Types inherited from QwtPlotRasterItem 🎀

  • enum CachePolicy { NoCache, PaintCache } — cache policy vibes; the default policy is NoCache.
  • enum PaintAttribute { PaintInDeviceResolution = 1 } — paint attribute energy.
  • typedef QFlags< PaintAttribute > PaintAttributes — flags combo for 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_PlotGraphic, Rtti_PlotTradingCurve,
    Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape,
    Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotVectorField,
    Rtti_PlotUserItem = 1000 }

Runtime type information, periodt.

  • enum ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 } — plot item attributes, lowkey essential.
  • enum ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 } — plot item interests.
  • enum RenderHint { RenderAntialiased = 0x1 } — render hints, cute.
  • typedef QFlags< ItemAttribute > ItemAttributes — flags for item attributes.
  • typedef QFlags< ItemInterest > ItemInterests — flags for item interests.
  • typedef QFlags< RenderHint > RenderHints — flags for render hints.

💖 Public Member Functions 💖

  • QwtPlotSpectrogram (const QString &title=QString()) — constructor bestie.
  • virtual ~QwtPlotSpectrogram () — destructor.
  • void setDisplayMode (DisplayMode, bool on=true) — set a display mode on or off.
  • bool testDisplayMode (DisplayMode) const — check whether a display mode is on.
  • void setData (QwtRasterData *data) — give it the raster data.
  • const QwtRasterData * data () const — const access to the data.
  • QwtRasterData * data () — non-const access to the data.
  • void setColorMap (QwtColorMap *) — set the color map.
  • const QwtColorMap * colorMap () const — get the color map.
  • void setColorTableSize (int numColors) — set how many colors are in the color table.
  • int colorTableSize () const — get the color table size.
  • virtual QwtInterval interval (Qt::Axis) const override — interval override.
  • virtual QRectF pixelHint (const QRectF &) const override — pixel hint.
  • void setDefaultContourPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine) — set the default contour pen from a color, width, and pen style.
  • void setDefaultContourPen (const QPen &) — set the default pen for the contour lines.
  • QPen defaultContourPen () const — get the default contour pen.
  • virtual QPen contourPen (double level) const — calculate the pen for a contour line.
  • void setConrecFlag (QwtRasterData::ConrecFlag, bool on) — set a CONREC flag.
  • bool testConrecFlag (QwtRasterData::ConrecFlag) const — check a CONREC flag.
  • void setContourLevels (const QList< double > &) — set the contour levels.
  • QList< double > contourLevels () const — get the contour levels.
  • virtual int rtti () const override — runtime type info override.
  • virtual void draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const override — draw the spectrogram.

🫶 Public Member Functions inherited from QwtPlotRasterItem 🫶

  • QwtPlotRasterItem (const QString &title=QString()) — constructor.
  • QwtPlotRasterItem (const QwtText &title) — constructor.
  • virtual ~QwtPlotRasterItem () — destructor.
  • void setPaintAttribute (PaintAttribute, bool on=true) — set a paint attribute.
  • bool testPaintAttribute (PaintAttribute) const — test a paint attribute.
  • void setAlpha (int alpha) — set an alpha value for the raster data.
  • int alpha () const — get the alpha value.
  • void setCachePolicy (CachePolicy) — set the cache policy.
  • CachePolicy cachePolicy () const — get the cache policy.
  • void invalidateCache () — invalidate the cache.
  • virtual QRectF boundingRect () const override — bounding rectangle override.

🦋 Public Member Functions inherited from QwtPlotItem 🦋

  • QwtPlotItem () — constructor.
  • QwtPlotItem (const QString &title) — constructor.
  • QwtPlotItem (const QwtText &title) — constructor.
  • virtual ~QwtPlotItem () — destroy the QwtPlotItem.
  • void attach (QwtPlot *plot) — attach the item to a plot.
  • void detach () — this method detaches a QwtPlotItem from any QwtPlot it has been associated with.
  • QwtPlot * plot () const — return attached plot.
  • void setTitle (const QString &title) — set the title.
  • void setTitle (const QwtText &title) — set the title as QwtText.
  • const QwtText & title () const — get the title.
  • void setItemAttribute (ItemAttribute, bool on=true) — set an item attribute.
  • bool testItemAttribute (ItemAttribute) const — test an item attribute.
  • void setItemInterest (ItemInterest, bool on=true) — set an item interest.
  • bool testItemInterest (ItemInterest) const — test an item interest.
  • void setRenderHint (RenderHint, bool on=true) — set a render hint.
  • bool testRenderHint (RenderHint) const — test a render hint.
  • void setRenderThreadCount (uint numThreads) — set the render thread count.
  • uint renderThreadCount () const — get the render thread count.
  • void setLegendIconSize (const QSize &) — set the legend icon size.
  • QSize legendIconSize () const — get the legend icon size.
  • double z () const — get the z value.
  • void setZ (double z) — set the z value.
  • void show () — show the item.
  • void hide () — hide the item.
  • virtual void setVisible (bool) — set visibility.
  • bool isVisible () const — is it visible?
  • void setAxes (QwtAxisId xAxis, QwtAxisId yAxis) — set both axes.
  • void setXAxis (QwtAxisId) — set the x axis.
  • QwtAxisId xAxis () const — return xAxis.
  • void setYAxis (QwtAxisId) — set the y axis.
  • QwtAxisId yAxis () const — return yAxis.
  • virtual void itemChanged () — item changed hook.
  • virtual void legendChanged () — legend changed hook.
  • 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.
  • virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &) — update the item to changes of the axes scale division.
  • virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &) — update the item to changes of the legend info.
  • QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const — calculate the bounding scale rectangle of 2 maps.
  • QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const — calculate the bounding paint rectangle of 2 maps.
  • virtual QList< QwtLegendData > legendData () const — return all information that is needed to represent the item on the legend.
  • virtual QwtGraphic legendIcon (int index, const QSizeF &) const — legend icon hook.

🔥 Protected Member Functions 🔥

  • virtual QImage renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &area, const QSize &imageSize) const override — render an image from data and color map.
  • virtual QSize contourRasterSize (const QRectF &, const QRect &) const — return the raster to be used by the CONREC contour algorithm.
  • virtual QwtRasterData::ContourLines renderContourLines (const QRectF &rect, const QSize &raster) const — render contour lines.
  • virtual void drawContourLines (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtRasterData::ContourLines &) const — draw contour lines.
  • void renderTile (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &tile, QImage *) const — render a tile of an image.

🌸 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.

🎀 Protected Member Functions inherited from QwtPlotItem 🎀

  • QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const — return a default icon from a brush.

🌟 DETAILED DESCRIPTION 🌟

A plot item, which displays a spectrogram. That's the main-character energy right there 💅

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. So pretty, so math, we love to see it ✨

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()). fr fr, tiling goes hard.

In ContourMode contour lines are painted for the contour levels. iconic behavior.

See also: QwtRasterData, QwtColorMap, QwtPlotItem::setRenderThreadCount()

Definition at line 36 of file qwt_plot_spectrogram.h.

🧚 MEMBER TYPEDEF DOCUMENTATION 🧚

okay so this one:

typedef QFlags<DisplayMode > QwtPlotSpectrogram::DisplayModes

An ORed combination of DisplayMode values. No cap, it's literally a flags combo.

Definition at line 53 of file qwt_plot_spectrogram.h.

💜 MEMBER ENUMERATION DOCUMENTATION 💜

enum QwtPlotSpectrogram::DisplayMode

The display mode controls how the raster data will be represented. vibe check for your data rendering 💖

See also: setDisplayMode(), testDisplayMode()

Enumerator

  • ImageMode — the values are mapped to colors using a color map. slay.
  • ContourMode — the data is displayed using contour lines. also slay.

Definition at line 44 of file qwt_plot_spectrogram.h.

🎀 CONSTRUCTOR & DESTRUCTOR DOCUMENTATION 🎀

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

[explicit]

Sets the following item attributes:

  • QwtPlotItem::AutoScale: true
  • QwtPlotItem::Legend: false

The z value is initialized by 8.0. periodt.

Parameters

  • title — Title
See also: QwtPlotItem::setItemAttribute(), QwtPlotItem::setZ()

Definition at line 108 of file qwt_plot_spectrogram.cpp.

QwtPlotSpectrogram::~QwtPlotSpectrogram ()

[virtual]

Destructor. bye bestie 😭

Definition at line 120 of file qwt_plot_spectrogram.cpp.

⭐ MEMBER FUNCTION DOCUMENTATION ⭐

const QwtColorMap * QwtPlotSpectrogram::colorMap () const

Returns: Color Map used for mapping the intensity values to colors. the glow-up map, iykyk.

See also: setColorMap()

Definition at line 200 of file qwt_plot_spectrogram.cpp.

int QwtPlotSpectrogram::colorTableSize () const

Returns: Size of the color table; 0 means not using a color table. zero means no table, bestie, don't forget.

See also: QwtColorMap::colorTable(), setColorTableSize()

Definition at line 238 of file qwt_plot_spectrogram.cpp.

QList< double > QwtPlotSpectrogram::contourLevels () const

Returns: Levels of the contour lines.

The levels are sorted in increasing order. lowkey tidy.

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

Definition at line 382 of file qwt_plot_spectrogram.cpp.

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. cute pen logic, no cap 🖊️

Parameters

  • level — Contour level

Returns: Pen for the contour line

Note: contourPen is only used if defaultContourPen().style() == Qt::NoPen. that's the rule, bestie, don't skip it.
See also: setDefaultContourPen(), setColorMap(), setContourLevels()

Definition at line 303 of file qwt_plot_spectrogram.cpp.

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

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. it's giving "more precision, more waiting" energy 😭

The default implementation returns rect.size() / 2 bounded to the resolution depending on pixelSize().

Parameters

  • area — Rectangle, where to calculate the contour lines
  • rect — Rectangle 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().

Definition at line 663 of file qwt_plot_spectrogram.cpp.

💖 data() — the non-const getter

QwtRasterData * QwtPlotSpectrogram::data ()

Returns the spectrogram data, bestie.

  • Returns: Spectrogram data
  • See also: setData()
  • Definition at line 418 of file qwt_plot_spectrogram.cpp.

✨ data() const — the const getter

const QwtRasterData * QwtPlotSpectrogram::data () const

Same data vibes, but const this time. Iconic.

  • Returns: Spectrogram data
  • See also: setData()
  • Definition at line 409 of file qwt_plot_spectrogram.cpp.

🎀 defaultContourPen()

QPen QwtPlotSpectrogram::defaultContourPen () const

Returns the default contour pen.

  • Returns: Default contour pen
  • See also: setDefaultContourPen()
  • Definition at line 287 of file qwt_plot_spectrogram.cpp.

🦋 draw() — main character draw energy

void QwtPlotSpectrogram::draw (QPainter * painter, const QwtScaleMap & xMap,
    const QwtScaleMap & yMap, const QRectF & canvasRect) const [override],
    [virtual]

Draws the spectrogram. Slay.

  • Parameters:
    • painter — Painter
    • xMap — Maps x-values into pixel coordinates.
    • yMap — Maps y-values into pixel coordinates.
    • canvasRect — Contents rectangle of the canvas in painter coordinates
  • See also: setDisplayMode(), renderImage(), QwtPlotRasterItem::draw(), drawContourLines()
  • Reimplemented from QwtPlotRasterItem.
  • Definition at line 754 of file qwt_plot_spectrogram.cpp.

🌸 drawContourLines() — protected contour painting

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

Paints the contour lines. Very demure, very contour.

  • 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()
  • Definition at line 709 of file qwt_plot_spectrogram.cpp.

🫶 interval() — bounding interval tea

QwtInterval QwtPlotSpectrogram::interval (Qt::Axis axis) const [override],
    [virtual]

Gives you the bounding interval for an axis.

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

  • Parameters:
    • axis — X, Y, or Z axis
  • Returns: Bounding interval for an axis
  • See also: QwtRasterData::interval()
  • Reimplemented from QwtPlotRasterItem.
  • Definition at line 432 of file qwt_plot_spectrogram.cpp.

🐚 pixelHint() — pixel geometry detective

QRectF QwtPlotSpectrogram::pixelHint (const QRectF & area) const [override],
    [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:
    • area — In 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.
  • Definition at line 456 of file qwt_plot_spectrogram.cpp.

🔥 renderContourLines() — protected contour calculation

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

Calculates contour lines. Math but make it fashion.

  • Parameters:
    • rect — Rectangle, where to calculate the contour lines
    • raster — Raster, used by the CONREC algorithm
  • Returns: Calculated contour lines
  • See also: contourLevels(), setConrecFlag(), QwtRasterData::contourLines()
  • Definition at line 689 of file qwt_plot_spectrogram.cpp.

🌈 renderImage() — pixels into colors

QImage QwtPlotSpectrogram::renderImage (const QwtScaleMap & xMap, const
    QwtScaleMap & yMap, const QRectF & area, const QSize & imageSize) const
    [override],  [protected],  [virtual]

Render an image from data and color map. For each pixel of area the value is mapped into a color.

  • Parameters:
    • xMap — X-Scale Map
    • yMap — Y-Scale Map
    • area — Requested area for the image in scale coordinates
    • imageSize — Size 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.
  • Definition at line 480 of file qwt_plot_spectrogram.cpp.

🌟 renderTile() — tile-by-tile rendering

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:
    • xMap — X-Scale Map
    • yMap — Y-Scale Map
    • tile — Geometry of the tile in image coordinates
    • image — Image to be rendered
  • Definition at line 572 of file qwt_plot_spectrogram.cpp.

💀 rtti() — runtime type info check

int QwtPlotSpectrogram::rtti () const [override],  [virtual]
  • Returns: QwtPlotItem::Rtti_PlotSpectrogram
  • Reimplemented from QwtPlotItem.
  • Definition at line 126 of file qwt_plot_spectrogram.cpp.

👑 setColorMap() — change the color map

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:
    • colorMap — Color Map
  • See also: colorMap(), QwtScaleWidget::setColorBarEnabled(), QwtScaleWidget::setColorMap()
  • Definition at line 177 of file qwt_plot_spectrogram.cpp.

🍓 setColorTableSize() — color table size limit

void QwtPlotSpectrogram::setColorTableSize (int numColors)

Limit the number of colors being used by the color map.

When using a color table the mapping from the value into a color is usually faster as it can be done by simple lookups into a precalculated color table.

Setting a table size > 0 enables using a color table, while setting the size to 0 disables it.

The default size = 0, and no color table is used.

  • Parameters:
    • numColors — Number of colors. 0 means not using a color table
  • Note: The colorTableSize has no effect when using a color table of QwtColorMap::Indexed, where the size is always 256.
  • See also: QwtColorMap::colorTable(), colorTableSize()
  • Definition at line 224 of file qwt_plot_spectrogram.cpp.

🧚 setConrecFlag() — CONREC algorithm switch

void QwtPlotSpectrogram::setConrecFlag (QwtRasterData::ConrecFlag flag, bool
    on)

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

  • Parameters:
    • flag — CONREC flag
    • on — On/Off
  • See also: testConrecFlag(), renderContourLines(), QwtRasterData::contourLines()
  • Definition at line 324 of file qwt_plot_spectrogram.cpp.

🎀 setContourLevels() — set those contour levels

void QwtPlotSpectrogram::setContourLevels (const QList< double > & 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.
  • Definition at line 365 of file qwt_plot_spectrogram.cpp.

💜 setData() — give it the data

void QwtPlotSpectrogram::setData (QwtRasterData * data)

Set the data to be displayed.

  • Parameters:
    • data — Spectrogram Data
  • See also: data()
  • Definition at line 393 of file qwt_plot_spectrogram.cpp.

🌸 setDefaultContourPen() — color, width, style edition

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:
    • color — Pen color
    • width — Pen width
    • style — Pen style
  • See also: pen(), brush()
  • Definition at line 256 of file qwt_plot_spectrogram.cpp.

🦋 setDefaultContourPen() — pen object edition

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()
  • Definition at line 272 of file qwt_plot_spectrogram.cpp.

✨ setDisplayMode() — display mode toggle

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()
  • Definition at line 141 of file qwt_plot_spectrogram.cpp.

🔍 testConrecFlag() — check that CONREC flag

bool QwtPlotSpectrogram::testConrecFlag (QwtRasterData::ConrecFlag flag)
    const

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

  • Parameters:
    • flag — CONREC flag
  • Returns: true, is enabled
  • The default setting enables QwtRasterData::IgnoreAllVerticesOnLevel
  • See also: setConrecClag(), renderContourLines(), QwtRasterData::contourLines()
  • Definition at line 350 of file qwt_plot_spectrogram.cpp.

🌈 testDisplayMode() — is that mode on?

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
  • Definition at line 161 of file qwt_plot_spectrogram.cpp.

👑 AUTHOR 👑

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