QwtPlotItem(3)

📦
version 6.3.0 · 6 versions
, in alpine 3.24

QwtPlotItem(3)

ok so bestie. this is straight out of the Library Functions Manual, and it's literally the blueprint for every single thing you can slap onto a Qwt plot canvas. buckle up 💖

✨ NAME ✨

QwtPlotItem — the base class for items on the plot canvas. like, the base class. the mother of them all 👑

🦋 SYNOPSIS 🦋

ok so here's the vibe right off the bat:

#include <qwt_plot_item.h>

Inherited by QwtPlotGraphicItem, QwtPlotGrid, QwtPlotLegendItem, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem, QwtPlotSeriesItem, QwtPlotShapeItem, QwtPlotTextLabel, and QwtPlotZoneItem. not a small family, ngl 🫶

🎀 Public Types

  • 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, iykyk
  • 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

  • QwtPlotItem ()
  • QwtPlotItem (const QString &title)
  • QwtPlotItem (const QwtText &title)
  • virtual ~QwtPlotItem () — destroy the QwtPlotItem. bye bestie 😭
  • 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)
  • void setTitle (const QwtText &title)
  • const QwtText & title () const
  • virtual int rtti () 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 void draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const =0 — draw the item
  • 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
  • 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

🌸 Protected Member Functions

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

🌈 Detailed Description 🌈

ok so: Base class for items on the plot canvas. periodt.

A plot item is "something" that can be painted on the plot canvas, or only affects the scales of the plot widget. they fall into two whole categories, and yes you need to know both 🔥

  • Representator — a "Representator" is an item that represents some sort of data on the plot canvas. the different representator classes are organized according to the characteristics of the data:
    • QwtPlotMarker — represents a point or a horizontal/vertical coordinate
    • QwtPlotCurve — represents a series of points
    • QwtPlotSpectrogram ( QwtPlotRasterItem ) — represents raster data
    • ...
  • Decorators — a "Decorator" is an item that displays additional information that is not related to any data:
    • QwtPlotGrid
    • QwtPlotScaleItem
    • QwtPlotSvgItem
    • ...

Depending on the QwtPlotItem::ItemAttribute flags, an item is included into autoscaling or has an entry on the legend.

bestie listen. before misusing the existing item classes, it might be better to implement a new type of plot item ( don't implement a watermark as spectrogram ). deriving a new type of QwtPlotItem primarily means implementing the YourPlotItem::draw() method. that's the whole assignment fr fr.

See also: the cpuplot example shows the implementation of additional plot items.

Definition at line 66 of file qwt_plot_item.h.

🧚 Member Typedef Documentation 🧚

typedef QFlags<ItemAttribute > QwtPlotItem::ItemAttributes

an ORed combination of ItemAttribute values.

Definition at line 167 of file qwt_plot_item.h.

typedef QFlags<ItemInterest > QwtPlotItem::ItemInterests

an ORed combination of ItemInterest values.

Definition at line 200 of file qwt_plot_item.h.

typedef QFlags<RenderHint > QwtPlotItem::RenderHints

an ORed combination of RenderHint values.

Definition at line 209 of file qwt_plot_item.h.

⭐ Member Enumeration Documentation ⭐

enum QwtPlotItem::ItemAttribute

Plot Item Attributes. various aspects of a plot widget depend on the attributes of the attached plot items. if and how a single plot item participates in these updates depends on its attributes.

See also: setItemAttribute(), testItemAttribute(), ItemInterest

Enumerators

  • Legend — the item is represented on the legend.
  • AutoScale — the boundingRect() of the item is included in the autoscaling calculation as long as its width or height is >= 0.0.
  • Margins — the item needs extra space to display something outside its bounding rectangle.

See also: getCanvasMarginHint()

Definition at line 147 of file qwt_plot_item.h.

enum QwtPlotItem::ItemInterest

Plot Item Interests. plot items might depend on the situation of the corresponding plot widget. by enabling an interest, the plot item will be notified when the corresponding attribute of the plot widgets has changed.

See also: setItemAttribute(), testItemAttribute(), ItemInterest

Enumerators

  • ScaleInterest — the item is interested in updates of the scales
    • See also: updateScaleDiv()
  • LegendInterest — the item is interested in updates of the legend ( of other items ). this flag is intended for items that want to implement a legend for displaying entries of other plot item.
    • > Note: if the plot item wants to be represented on a legend, enable QwtPlotItem::Legend instead.
    • See also: updateLegend()

Definition at line 179 of file qwt_plot_item.h.

enum QwtPlotItem::RenderHint

Render hints.

Enumerators

  • RenderAntialiased — enable antialiasing ✨

Definition at line 203 of file qwt_plot_item.h.

enum QwtPlotItem::RttiValues

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

Enumerators

  • Rtti_PlotItem — unspecific value that can be used when it doesn't matter.
  • Rtti_PlotGrid — for QwtPlotGrid.
  • Rtti_PlotScale — for QwtPlotScaleItem.
  • Rtti_PlotLegend — for QwtPlotLegendItem.
  • Rtti_PlotMarker — for QwtPlotMarker.
  • Rtti_PlotCurve — for QwtPlotCurve.
  • Rtti_PlotSpectroCurve — for QwtPlotSpectroCurve.
  • Rtti_PlotIntervalCurve — for QwtPlotIntervalCurve.
  • Rtti_PlotHistogram — for QwtPlotHistogram.
  • Rtti_PlotSpectrogram — for QwtPlotSpectrogram.
  • Rtti_PlotGraphic — for QwtPlotGraphicItem, QwtPlotSvgItem.
  • Rtti_PlotTradingCurve — for QwtPlotTradingCurve.
  • Rtti_PlotBarChart — for QwtPlotBarChart.
  • Rtti_PlotMultiBarChart — for QwtPlotMultiBarChart.
  • Rtti_PlotShape — for QwtPlotShapeItem.
  • Rtti_PlotTextLabel — for QwtPlotTextLabel.
  • Rtti_PlotZone — for QwtPlotZoneItem.
  • Rtti_PlotVectorField — for QwtPlotVectorField.
  • Rtti_PlotUserItem — values >= Rtti_PlotUserItem are reserved for plot items not implemented in the Qwt library.

Definition at line 75 of file qwt_plot_item.h.

💀 Constructor & Destructor Documentation 💀

QwtPlotItem::QwtPlotItem () [explicit]

Constructor. that's it. that's the whole description 🎀

Definition at line 55 of file qwt_plot_item.cpp.

QwtPlotItem::QwtPlotItem (const QString & title) [explicit]

Constructor.

Parameters

  • title — title of the item

Definition at line 64 of file qwt_plot_item.cpp.

QwtPlotItem::QwtPlotItem (const QwtText & title) [explicit]

Constructor.

Parameters

  • title — title of the item

Definition at line 74 of file qwt_plot_item.cpp.

QwtPlotItem::~QwtPlotItem () [virtual]

Destroy the QwtPlotItem. rest in peace queen 😭👑

Definition at line 81 of file qwt_plot_item.cpp.

🔥 Member Function Documentation 🔥

void QwtPlotItem::attach (QwtPlot * plot)

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. so like, it's a glow-up AND a break-up in one call 💅

Parameters

  • plot — plot widget

See also: detach()

Definition at line 98 of file qwt_plot_item.cpp.

QRectF QwtPlotItem::boundingRect () const [virtual]

Returns an invalid bounding rect: QRectF(1.0, 1.0, -2.0, -2.0)

Note: a width or height < 0.0 is ignored by the autoscaler.

Reimplemented in QwtPlotBarChart, QwtPlotGraphicItem, QwtPlotHistogram, QwtPlotIntervalCurve, QwtPlotMarker, QwtPlotMultiBarChart, QwtPlotRasterItem, QwtPlotSeriesItem, QwtPlotShapeItem, QwtPlotTradingCurve, QwtPlotVectorField, and QwtPlotZoneItem.

Definition at line 568 of file qwt_plot_item.cpp.

QwtGraphic QwtPlotItem::defaultIcon (const QBrush & brush, const QSizeF & size) const [protected]

bestie this is your default icon maker ✨ It takes a brush and a size, and hands you back a filled rectangle. Several derived classes use this as their legendIcon() — iconic behavior honestly 🎀

  • brush — Fill brush 🖌️
  • size — Icon size 📏

Returns — A filled rectangle 🫶

Definition at line 422 of file qwt_plot_item.cpp.

void QwtPlotItem::detach ()

Not me detaching from every QwtPlot I’ve ever been associated with 😭 This method does exactly that. Also lowkey it’s equivalent to calling attach( NULL ) — same energy, fr fr.

See also — attach()

Definition at line 119 of file qwt_plot_item.cpp.

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

Okay so this is the big one — pure virtual, meaning you have to implement it in your derived class, no cap. It draws the item. Periodt 💅

  • 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.

Implemented in QwtPlotGraphicItem, QwtPlotGrid, QwtPlotLegendItem, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem, QwtPlotSeriesItem, QwtPlotShapeItem, QwtPlotSpectrogram, QwtPlotTextLabel, and QwtPlotZoneItem.

void QwtPlotItem::getCanvasMarginHint (const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, double & left, double & top, double & right, double & bottom) const [virtual]

Vibe check: this calculates a hint for the canvas margin. When the QwtPlotItem::Margins flag is enabled, the plot item is basically saying “hey I need some margins at the borders of the canvas”. For example, bar charts use this to reserve space for displaying the bars. The margins are in target device coordinates ( pixels on screen ) — important detail bestie 👀

  • xMap — Maps x-values into pixel coordinates.
  • yMap — Maps y-values into pixel coordinates.
  • canvasRect — Contents rectangle of the canvas in painter coordinates.
  • left — Returns the left margin.
  • top — Returns the top margin.
  • right — Returns the right margin.
  • bottom — Returns the bottom margin.

The default implementation returns 0 for all margins — so if you don’t override it, it’s giving zero margins, no drama 🌸

See also — QwtPlot::getCanvasMarginsHint(), QwtPlot::updateCanvasMargins()

Reimplemented in QwtPlotAbstractBarChart.

Definition at line 595 of file qwt_plot_item.cpp.

void QwtPlotItem::hide ()

Hide the item. That’s it. That’s the tweet. 💅

Definition at line 446 of file qwt_plot_item.cpp.

bool QwtPlotItem::isVisible () const

Returns true if visible 👀

See also — setVisible(), show(), hide()

Definition at line 470 of file qwt_plot_item.cpp.

void QwtPlotItem::itemChanged () [virtual]

Update the legend and call QwtPlot::autoRefresh() for the parent plot. So it’s like “hey legend, refresh yourself, and also auto-refresh the plot”. Multitasking icon ✨

See also — QwtPlot::legendChanged(), QwtPlot::autoRefresh()

Definition at line 481 of file qwt_plot_item.cpp.

void QwtPlotItem::legendChanged () [virtual]

Update the legend of the parent plot. Simple as that 🫶

See also — QwtPlot::updateLegend(), itemChanged()

Definition at line 491 of file qwt_plot_item.cpp.

QList< QwtLegendData > QwtPlotItem::legendData () const [virtual]

Return all the info needed to represent the item on the legend. Most items are represented by one entry on the legend showing an icon and a text — but f.e. QwtPlotMultiBarChart displays one entry for each bar. So it can be a whole vibe 🌈

QwtLegendData is basically a list of QVariants that makes it possible to overload and reimplement legendData() to return almost any type of information that is understood by the receiver that acts as the legend. So you can go wild with it, iykyk 💜

The default implementation returns one entry with the title() of the item and the legendIcon().

Returns — Data, that is needed to represent the item on the legend.

See also — title(), legendIcon(), QwtLegend, QwtPlotLegendItem

Reimplemented in QwtPlotBarChart, and QwtPlotMultiBarChart.

Definition at line 626 of file qwt_plot_item.cpp.

QwtGraphic QwtPlotItem::legendIcon (int index, const QSizeF & size) const [virtual]

Returns — Icon representing the item on the legend.

The default implementation returns an invalid icon — so it’s giving “no icon for you” by default, but you can override it 💅

  • index — Index of the legend entry ( usually there is only one )
  • size — Icon size

See also — setLegendIconSize(), legendData()

Reimplemented in QwtPlotBarChart, QwtPlotCurve, QwtPlotHistogram, QwtPlotIntervalCurve, QwtPlotMarker, QwtPlotMultiBarChart, QwtPlotShapeItem, QwtPlotTradingCurve, and QwtPlotVectorField.

Definition at line 402 of file qwt_plot_item.cpp.

QSize QwtPlotItem::legendIconSize () const

Returns the legend icon size. That’s it. 📏

See also — setLegendIconSize(), legendIcon()

Definition at line 386 of file qwt_plot_item.cpp.

QRectF QwtPlotItem::paintRect (const QwtScaleMap & xMap, const QwtScaleMap & yMap) const

Calculate the bounding paint rectangle of 2 maps. It’s giving geometry realness ✨

  • xMap — Maps x-values into pixel coordinates.
  • yMap — Maps y-values into pixel coordinates.

Returns — Bounding paint rectangle of the scale maps, not normalized.

Definition at line 720 of file qwt_plot_item.cpp.

QwtPlot * QwtPlotItem::plot () const

Return attached plot. Like, which plot are you attached to bestie? This tells you. 🫶

Definition at line 142 of file qwt_plot_item.cpp.

uint QwtPlotItem::renderThreadCount () const

Returns the number of threads to be used for rendering. If numThreads() is set to 0, the system specific ideal thread count is used. So 0 means “let the system decide”, iconic 💅

Definition at line 360 of file qwt_plot_item.cpp.

int QwtPlotItem::rtti () const [virtual]

Return rtti for the specific class represented. QwtPlotItem is simply a virtual interface class, and base classes will implement this method with specific rtti values so a user can differentiate them. The rtti value is useful for environments where the runtime type information is disabled and it is not possible to do a dynamic_cast<...>. So it’s like a backup vibe check for when RTTI is off 👑

Returns — rtti value.

See also — RttiValues

Reimplemented in QwtPlotBarChart, QwtPlotCurve, QwtPlotGraphicItem, QwtPlotGrid, QwtPlotHistogram, QwtPlotIntervalCurve, QwtPlotLegendItem, QwtPlotMarker, QwtPlotMultiBarChart, QwtPlotScaleItem, QwtPlotShapeItem, QwtPlotSpectroCurve, QwtPlotSpectrogram, QwtPlotTextLabel, QwtPlotTradingCurve, QwtPlotVectorField, and QwtPlotZoneItem.

Definition at line 136 of file qwt_plot_item.cpp.

QRectF QwtPlotItem::scaleRect (const QwtScaleMap & xMap, const QwtScaleMap & yMap) const

Calculate the bounding scale rectangle of 2 maps. Similar to paintRect but for scale. Slay 🌸

  • xMap — Maps x-values into pixel coordinates.
  • yMap — Maps y-values into pixel coordinates.

Returns — Bounding scale rect of the scale maps, not normalized.

Definition at line 705 of file qwt_plot_item.cpp.

void QwtPlotItem::setAxes (QwtAxisId xAxisId, QwtAxisId yAxisId)

Set X and Y axis. The item will be painted according to the coordinates of its Axes. So if you change the axes, the item follows. Main character energy ✨

  • xAxisId — X Axis
  • yAxisId — Y Axis

See also — setXAxis(), setYAxis(), xAxis(), yAxis()

Definition at line 507 of file qwt_plot_item.cpp.

void QwtPlotItem::setItemAttribute (ItemAttribute attribute, bool on = true)

Toggle an item attribute. You pass the attribute type and true/false for on. Default is true because why not 💅

  • attribute — Attribute type
  • on — true/false

See also — testItemAttribute(), ItemInterest

Definition at line 228 of file qwt_plot_item.cpp.

void QwtPlotItem::setItemInterest (ItemInterest interest, bool on = true)

Toggle an item interest. Same vibe as setItemAttribute but for interests 👀

  • interest — Interest type
  • on — true/false

See also — testItemInterest(), ItemAttribute

Definition at line 279 of file qwt_plot_item.cpp.

void QwtPlotItem::setLegendIconSize (const QSize & size)

Set the size of the legend icon. The default setting is 8x8 pixels — tiny but mighty 🎀

  • size — Size

See also — legendIconSize(), legendIcon()

Definition at line 373 of file qwt_plot_item.cpp.

void QwtPlotItem::setRenderHint (RenderHint hint, bool on = true)

Toggle a render hint. You know the drill: hint, and on/off. 🌟

  • hint — Render hint
  • on — true/false

See also — testRenderHint(), RenderHint

Definition at line 312 of file qwt_plot_item.cpp.

void QwtPlotItem::setRenderThreadCount (uint numThreads)

On multi core systems, rendering of certain plot item ( f.e QwtPlotRasterItem ) can be done in parallel in several threads. The default setting is set to 1. So by default you’re not adding extra threads — it’s giving single-threaded simplicity 🧚

  • numThreads — Number of threads to be used for rendering. If numThreads is set to 0, the system specific ideal thread count is used.

The default thread count is 1 ( = no additional threads )

Definition at line 350 of file qwt_plot_item.cpp.

void QwtPlotItem::setTitle (const QString & title)

Set a new title. Give your item a name bestie 💖

  • title — Title

See also — title()

Definition at line 187 of file qwt_plot_item.cpp.

void QwtPlotItem::setTitle (const QwtText & title)

Set a new title, but with a QwtText this time. Fancy ✨

  • title — Title

See also — title()

Definition at line 198 of file qwt_plot_item.cpp.

void QwtPlotItem::setVisible (bool on) [virtual]

Show/Hide the item. Pass true to show, false to hide. Simple. 👑

  • on — Show if true, otherwise hide

See also — isVisible(), show(), hide()

Definition at line 457 of file qwt_plot_item.cpp.

void QwtPlotItem::setXAxis (QwtAxisId axisId)

Set the X axis. The item will be painted according to the coordinates its Axes. (Yes, the original says “according to the coordinates its Axes” — keep it exact, no cap.) 🫶

  • axisId — X Axis

See also — setAxes(), setYAxis(), xAxis()

Definition at line 526 of file qwt_plot_item.cpp.

void QwtPlotItem::setYAxis (QwtAxisId axisId)

Set the Y axis. The item will be painted according to the coordinates its Axes. Same energy as setXAxis but Y. 🌸

  • axisId — Y Axis

See also — setAxes(), setXAxis(), yAxis()

Definition at line 543 of file qwt_plot_item.cpp.

void QwtPlotItem::setZ (double z)

Set the z value. Plot items are painted in increasing z-order. So higher z = painted later = on top. Iconic layering 🔥

  • z — Z-value

See also — z(), QwtPlotDict::itemList()

Definition at line 165 of file qwt_plot_item.cpp.

void QwtPlotItem::show ()

Show the item. The opposite of hide(). Periodt 💅

Definition at line 440 of file qwt_plot_item.cpp.

bool QwtPlotItem::testItemAttribute (ItemAttribute attribute) const

Test an item attribute. Returns true/false. Vibe check for attributes ✨

  • attribute — Attribute type

Returns — true/false

See also — setItemAttribute(), ItemInterest

Definition at line 266 of file qwt_plot_item.cpp.

bool QwtPlotItem::testItemInterest (ItemInterest interest) const

Test an item interest. Returns true/false. Vibe check for interests 👀

  • interest — Interest type

Returns — true/false

See also — setItemInterest(), ItemAttribute

Definition at line 299 of file qwt_plot_item.cpp.

bool QwtPlotItem::testRenderHint (RenderHint hint) const

Test a render hint. Returns true/false. Last but not least 🫶

  • hint — Render hint

Returns — true/false

See also — setRenderHint(), RenderHint

Definition at line 332 of file qwt_plot_item.cpp — that's the tail end of setTitle(), bestie, we're done with that one, moving on 💅

🎀 title() — the lil name-tag reader

const QwtText & QwtPlotItem::title() const

Your Returns card says it all: this hands you back the Title of the item. That's it, that's the whole vibe ✨

See also: setTitle() (the one that actually sets it, obviously 🙈)

Definition at line 215 of file qwt_plot_item.cpp.

👑 updateLegend() — the legend glow-up hook

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

Okay so this one is literally about updating the item when the legend info changes. And here's the important lil distinction, no cap: plot items that want to display a legend (not those that want to be displayed on a legend!) have to implement updateLegend() 👀 like, read that twice, it matters.

updateLegend() is only called when the LegendInterest interest is enabled. The default implementation does nothing — a whole lot of nothing, honestly 💀

Parameters:

  • item — the plot item that's being displayed on a legend
  • data — the attributes for how to display the item on the legend

See also: QwtPlotLegendItem

Note, bestie, write this down: plot items that want to be displayed on a legend need to enable the QwtPlotItem::Legend flag and implement legendData() and legendIcon() 🫶

Reimplemented in QwtPlotLegendItem.

Definition at line 690 of file qwt_plot_item.cpp.

🦋 updateScaleDiv() — the axes-changed heads-up

void QwtPlotItem::updateScaleDiv(const QwtScaleDiv & xScaleDiv, const QwtScaleDiv & yScaleDiv) [virtual]

This is your "hey girl, the axes moved" notification 🌈 It updates the item whenever the axes of the plot have changed. The default implementation does nothing, but items that actually depend on the scale division (like QwtPlotGrid(), our grid icon ⭐) have to reimplement updateScaleDiv().

And repeat after me: updateScaleDiv() is only called when the ScaleInterest interest is enabled. The default implementation does nothing 🧚

Parameters:

  • xScaleDiv — scale division of the x-axis
  • yScaleDiv — scale division of the y-axis

See also: QwtPlot::updateAxes(), ScaleInterest

Reimplemented in QwtPlotGrid, QwtPlotScaleItem, and QwtPlotSeriesItem.

Definition at line 665 of file qwt_plot_item.cpp.

💜 xAxis() — which x you on?

QwtAxisId QwtPlotItem::xAxis() const

Return xAxis. Periodt. Short queen energy 👑

Definition at line 553 of file qwt_plot_item.cpp.

💜 yAxis() — and which y?

QwtAxisId QwtPlotItem::yAxis() const

Return yAxis. Matching set, we love a coordinated moment ✨

Definition at line 559 of file qwt_plot_item.cpp.

🔥 z() — the stacking order, aka main character ranking

double QwtPlotItem::z() const

Plot items are painted in increasing z-order — so the higher your z, the more you're in front of the whole plot. Main character energy, honestly 💅

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

Definition at line 152 of file qwt_plot_item.cpp.

🌸 Author 🌸

Generated automatically by Doxygen for Qwt User's Guide from the source code. Not me, not you, not the group chat — Doxygen did that 🎀

And that's the whole page, bestie! 🫶 This little masterpiece comes to you from the Qwt User's Guide, page QwtPlotItem(3), with the source and version info tucked right there in the footer line — so if you ever need to cite it, that's your receipt 💖 Go forth and plot, icon. 🦋✨
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