QwtPlotLegendItem(3)

📦
version 6.3.0 · 4 versions
, in alpine 3.24

🌸 NAME 🌸

Okay bestie, welcome to the QwtPlotLegendItem(3) page from the Library Functions Manual. This class draws a legend inside the plot canvas — literally the canvas-legend main character. 💅

✨ SYNOPSIS ✨

#include <qwt_plot_legenditem.h>

Inherits QwtPlotItem — yes, she's part of the plot-item family tree. 🫶

🎀 Public Types 🎀

  • enum BackgroundMode { LegendBackground, ItemBackground } — background mode. The vibe selector for where the background goes.

🦋 Public Types inherited from QwtPlotItem 🦋

  • enum RttiValues — runtime type information. The exact values are:
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 }
  • enum ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 } — plot item attributes.
  • enum ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 } — plot item interests.
  • enum RenderHint { RenderAntialiased = 0x1 } — render hints.
  • typedef QFlags< ItemAttribute > ItemAttributes
  • typedef QFlags< ItemInterest > ItemInterests
  • typedef QFlags< RenderHint > RenderHints

💅 Public Member Functions 💅

  • QwtPlotLegendItem () — constructor.
  • virtual ~QwtPlotLegendItem () — destructor.
  • virtual int rtti () const override — runtime type info override.
  • void setAlignmentInCanvas (Qt::Alignment) — set the alignment.
  • Qt::Alignment alignmentInCanvas () const
  • void setOffsetInCanvas (Qt::Orientations, int numPixels) — set the distance between the legend and the canvas border.
  • int offsetInCanvas (Qt::Orientation) const
  • void setMaxColumns (uint) — limit the number of columns.
  • uint maxColumns () const
  • void setMargin (int) — set the margin around legend items.
  • int margin () const
  • void setSpacing (int) — set the spacing between the legend items.
  • int spacing () const
  • void setItemMargin (int)
  • int itemMargin () const
  • void setItemSpacing (int)
  • int itemSpacing () const
  • void setFont (const QFont &)
  • QFont font () const
  • void setBorderRadius (double)
  • double borderRadius () const
  • void setBorderPen (const QPen &)
  • QPen borderPen () const
  • void setBackgroundBrush (const QBrush &) — set the background brush.
  • QBrush backgroundBrush () const
  • void setBackgroundMode (BackgroundMode) — set the background mode.
  • BackgroundMode backgroundMode () const
  • void setTextPen (const QPen &) — set the pen for drawing text labels.
  • QPen textPen () const
  • virtual void draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const override
  • void clearLegend () — remove all items from the legend.
  • virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &) override
  • virtual QRect geometry (const QRectF &canvasRect) const
  • virtual QSize minimumSize (const QwtLegendData &) const
  • virtual int heightForWidth (const QwtLegendData &, int width) const
  • QList< const QwtPlotItem * > plotItems () const
  • QList< QRect > legendGeometries (const QwtPlotItem *) const

🌈 Public Member Functions inherited from QwtPlotItem 🌈

  • QwtPlotItem ()
  • QwtPlotItem (const QString &title)
  • QwtPlotItem (const QwtText &title)
  • virtual ~QwtPlotItem () — destroy the QwtPlotItem.
  • void attach (QwtPlot *plot) — attach the item to a plot.
  • void detach () — detaches a QwtPlotItem from any QwtPlot it has been associated with.
  • QwtPlot * plot () const — return attached plot.
  • void setTitle (const QString &title)
  • void setTitle (const QwtText &title)
  • const QwtText & title () 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.
  • void show () — show the item.
  • void hide () — hide the item.
  • virtual void setVisible (bool)
  • bool isVisible () const
  • void setAxes (QwtAxisId xAxis, QwtAxisId yAxis)
  • void setXAxis (QwtAxisId)
  • QwtAxisId xAxis () const — return xAxis.
  • void setYAxis (QwtAxisId)
  • QwtAxisId yAxis () const — return yAxis.
  • virtual void itemChanged ()
  • virtual void legendChanged ()
  • virtual QRectF boundingRect () const
  • 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.
  • 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

🧚 Protected Member Functions 🧚

  • virtual void drawLegendData (QPainter *, const QwtPlotItem *, const QwtLegendData &, const QRectF &) const
  • virtual void drawBackground (QPainter *, const QRectF &rect) const

🦋 Protected Member Functions inherited from QwtPlotItem 🦋

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

💖 Detailed Description 💖

Okay so QwtPlotLegendItem draws a legend inside the plot canvas. It can be used together with a QwtLegend or instead of it to have more space for the plot canvas. Slay for canvas real estate.

Unlike QwtLegend, the legend item is not interactive. To identify mouse clicks on a legend item, an event filter needs to be installed catching mouse events on the plot canvas. The geometries of the legend items are available using legendGeometries(). iykyk

The legend item is aligned to the plot canvas according to its alignment() flags. It might have a background for the complete legend (usually semi transparent) or for each legend item.

Note: An external QwtLegend with a transparent background on top of the plot canvas might be another option with a similar effect.

Definition at line 41 of file qwt_plot_legenditem.h.

🔥 Member Enumeration Documentation 🔥

enum QwtPlotLegendItem::BackgroundMode

Background mode. Depending on the mode, the complete legend or each item might have a background.

The default setting is LegendBackground.

See also: setBackgroundMode(), setBackgroundBrush(), drawBackground()

Enumerator:

  • LegendBackground — the legend has a background.
  • ItemBackground — each item has a background.

Definition at line 54 of file qwt_plot_legenditem.h.

🎀 Constructor & Destructor Documentation 🎀

QwtPlotLegendItem::QwtPlotLegendItem () [explicit]

Constructor. Iconic.

Definition at line 175 of file qwt_plot_legenditem.cpp.

QwtPlotLegendItem::~QwtPlotLegendItem () [virtual]

Destructor. Cleanup queen.

Definition at line 185 of file qwt_plot_legenditem.cpp.

💖 Member Function Documentation 💖

Okay bestie, this is the function-by-function era — every getter, setter, draw hook and override, all accounted for. ✨

Qt::Alignment QwtPlotLegendItem::alignmentInCanvas () const

  • Returns: Alignment flags
  • See also: setAlignmentInCanvas()
  • Definition: at line 223 of file qwt_plot_legenditem.cpp.

QBrush QwtPlotLegendItem::backgroundBrush () const

  • Returns: Brush is used to fill the background
  • See also: setBackgroundBrush(), backgroundMode(), drawBackground()
  • Definition: at line 522 of file qwt_plot_legenditem.cpp.

QwtPlotLegendItem::BackgroundMode QwtPlotLegendItem::backgroundMode () const

  • Returns: backgroundMode
  • See also: setBackgroundMode(), backgroundBrush(), drawBackground()
  • Definition: at line 550 of file qwt_plot_legenditem.cpp.

QPen QwtPlotLegendItem::borderPen () const

  • Returns: Pen for drawing the border
  • See also: setBorderPen(), backgroundBrush()
  • Definition: at line 496 of file qwt_plot_legenditem.cpp.

double QwtPlotLegendItem::borderRadius () const

  • Returns: Radius of the border
  • See also: setBorderRadius(), setBorderPen()
  • Definition: at line 472 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::clearLegend ()

  • Remove all items from the legend.
  • Definition: at line 759 of file qwt_plot_legenditem.cpp.

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

  • Draw the legend
  • Parameters:
    • painter — Painter
    • xMap — x Scale Map
    • yMap — y Scale Map
    • canvasRect — Contents rectangle of the canvas in painter coordinates
  • Implements: QwtPlotItem.
  • Definition: at line 587 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::drawBackground (QPainter * painter, const QRectF & rect) const [protected], [virtual]

  • Draw a rounded rect
  • Parameters:
    • painter — Painter
    • rect — Bounding rectangle
  • See also: setBorderRadius(), setBorderPen(), setBackgroundBrush(), setBackgroundMode()
  • Definition: at line 630 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::drawLegendData (QPainter * painter, const QwtPlotItem * plotItem, const QwtLegendData & data, const QRectF & rect) const [protected], [virtual]

  • Draw an entry on the legend
  • Parameters:
    • painter — Qt Painter
    • plotItem — Plot item, represented by the entry
    • data — Attributes of the legend entry
    • rect — Bounding rectangle for the entry
  • Definition: at line 780 of file qwt_plot_legenditem.cpp.

QFont QwtPlotLegendItem::font () const

  • Returns: Font used for drawing the text label
  • See also: setFont()
  • Definition: at line 389 of file qwt_plot_legenditem.cpp.

QRect QwtPlotLegendItem::geometry (const QRectF & canvasRect) const [virtual]

  • Calculate the geometry of the legend on the canvas
  • Parameters:
    • canvasRect — Geometry of the canvas
  • Returns: Geometry of the legend
  • Definition: at line 650 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::heightForWidth (const QwtLegendData & data, int width) const [virtual]

  • Returns: The preferred height, for a width.
  • Parameters:
    • data — Attributes of the legend entry
    • width — Width
  • Definition: at line 862 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::itemMargin () const

  • Returns: Margin around each item
  • See also: setItemMargin(), itemSpacing(), margin(), spacing()
  • Definition: at line 335 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::itemSpacing () const

  • Returns: Spacing inside of each item
  • See also: setItemSpacing(), itemMargin(), margin(), spacing()
  • Definition: at line 363 of file qwt_plot_legenditem.cpp.

QList< QRect > QwtPlotLegendItem::legendGeometries (const QwtPlotItem * plotItem) const

  • Returns: Geometries of the items of a plot item
  • Note: Usually a plot item has only one entry on the legend
  • Definition: at line 895 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::margin () const

  • Returns: Margin around the legend items
  • See also: setMargin(), spacing(), itemMargin(), itemSpacing()
  • Definition: at line 280 of file qwt_plot_legenditem.cpp.

uint QwtPlotLegendItem::maxColumns () const

  • Returns: Maximum number of columns
  • See also: maxColumns(), QwtDynGridLayout::maxColumns()
  • Definition: at line 251 of file qwt_plot_legenditem.cpp.

QSize QwtPlotLegendItem::minimumSize (const QwtLegendData & data) const [virtual]

  • Minimum size hint needed to display an entry
  • Parameters:
    • data — Attributes of the legend entry
  • Returns: Minimum size
  • Definition: at line 823 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::offsetInCanvas (Qt::Orientation orientation) const

  • Parameters:
    • orientation — Qt::Horizontal is for the left/right, Qt::Vertical for the top/bottom padding.
  • Returns: Distance between the legend and the canvas border
  • See also: setOffsetInCanvas()
  • Definition: at line 444 of file qwt_plot_legenditem.cpp.

QList< const QwtPlotItem * > QwtPlotLegendItem::plotItems () const

  • Returns: All plot items with an entry on the legend
  • Note: A plot item might have more than one entry on the legend
  • Definition: at line 886 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::rtti () const [override], [virtual]

  • Returns: QwtPlotItem::Rtti_PlotLegend
  • Reimplemented from: QwtPlotItem.
  • Definition: at line 192 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setAlignmentInCanvas (Qt::Alignment alignment)

  • Set the alignment. Alignment means the position of the legend relative to the geometry of the plot canvas.
  • Parameters:
    • alignment — Alignment flags
  • See also: alignmentInCanvas(), setMaxColumns()
  • Note: To align a legend with many items horizontally the number of columns need to be limited
  • Definition: at line 210 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setBackgroundBrush (const QBrush & brush)

  • Set the background brush. The brush is used to fill the background
  • Parameters:
    • brush — Brush
  • See also: backgroundBrush(), setBackgroundMode(), drawBackground()
  • Definition: at line 509 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setBackgroundMode (BackgroundMode mode)

  • Set the background mode. Depending on the mode the complete legend or each item might have an background.
  • The default setting is LegendBackground.
  • See also: backgroundMode(), setBackgroundBrush(), drawBackground()
  • Definition: at line 537 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setBorderPen (const QPen & pen)

  • Set the pen for drawing the border
  • Parameters:
    • pen — Border pen
  • See also: borderPen(), setBackgroundBrush()
  • Definition: at line 483 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setBorderRadius (double radius)

  • Set the radius for the border
  • Parameters:
    • radius — A value <= 0 defines a rectangular border
  • See also: borderRadius(), setBorderPen()
  • Definition: at line 457 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setFont (const QFont & font)

  • Change the font used for drawing the text label
  • Parameters:
    • font — Legend font
  • See also: font()
  • Definition: at line 374 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setItemMargin (int margin)

  • Set the margin around each item
  • Parameters:
    • margin — Margin
  • See also: itemMargin(), setItemSpacing(), setMargin(), setSpacing()
  • Definition: at line 319 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setItemSpacing (int spacing)

  • Set the spacing inside of each item
  • Parameters:
    • spacing — Spacing
  • See also: itemSpacing(), setItemMargin(), setMargin(), setSpacing()
  • Definition: at line 346 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setMargin (int margin)

  • Set the margin around legend items. The default setting for the margin is 0.
  • Parameters:
    • margin — Margin in pixels
  • See also: margin(), setSpacing(), setItemMargin(), setItemSpacing
  • Definition: at line 264 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setMaxColumns (uint maxColumns)

  • Limit the number of columns. When aligning the legend horizontally ( Qt::AlignLeft, Qt::AlignRight ) the number of columns needs to be limited to avoid, that the width of the legend grows with an increasing number of entries.
  • Parameters:
    • maxColumns — Maximum number of columns. 0 means unlimited.
  • See also: maxColumns(), QwtDynGridLayout::setMaxColumns()
  • Definition: at line 238 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setOffsetInCanvas (Qt::Orientations orientations, int numPixels)

  • Set the distance between the legend and the canvas border. The default setting is 10 pixels.
  • Parameters:
    • orientations — Qt::Horizontal is for the left/right, Qt::Vertical for the top/bottom offset.
    • numPixels — Distance in pixels
  • See also: setMargin()
  • Definition: at line 405 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setSpacing (int spacing)

  • Set the spacing between the legend items.
  • Parameters:
    • spacing — Spacing in pixels
  • See also: spacing(), setMargin()
  • Definition: at line 294 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setTextPen (const QPen & pen)

  • Set the pen for drawing text labels.
  • Parameters:
    • pen — Text pen
  • See also: textPen(), setFont()
  • Definition: at line 561 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::spacing () const

  • Returns: Spacing between the legend items
  • See also: setSpacing(), margin(), itemSpacing(), itemMargin()
  • Definition: at line 308 of file qwt_plot_legenditem.cpp.

QPen QwtPlotLegendItem::textPen () const

  • Returns: Pen for drawing text labels
  • See also: setTextPen(), font()
  • Definition: at line 574 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::updateLegend (const QwtPlotItem * plotItem, const QList< QwtLegendData > & data) [override], [virtual]

  • Update the legend items according to modifications of a plot item
  • Parameters:
    • plotItem — Plot item
    • data — Attributes of the legend entries
  • Reimplemented from: QwtPlotItem.
  • Definition: at line 697 of file qwt_plot_legenditem.cpp.

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