QwtPlotScaleItem - A class which draws a scale inside the plot canvas.

NAME

QwtPlotScaleItem − A class which draws a scale inside the plot canvas.

SYNOPSIS

#include <qwt_plot_scaleitem.h>

Inherits QwtPlotItem.

Public Member Functions

QwtPlotScaleItem (QwtScaleDraw::Alignment=QwtScaleDraw::BottomScale, const double pos=0.0)
Constructor for scale item at the position pos.
virtual ˜QwtPlotScaleItem ()
Destructor.
virtual int rtti () const override
void setScaleDiv (const QwtScaleDiv &)
Assign a scale division.
const QwtScaleDiv & scaleDiv () const
void setScaleDivFromAxis (bool on)
bool isScaleDivFromAxis () const
void setPalette (const QPalette &)
QPalette palette () const
void setFont (const QFont &)
QFont font () const
void setScaleDraw (QwtScaleDraw *)
Set a scale draw.
const QwtScaleDraw * scaleDraw () const
QwtScaleDraw * scaleDraw ()
void setPosition (double pos)
double position () const
void setBorderDistance (int)
Align the scale to the canvas.
int borderDistance () const
void setAlignment (QwtScaleDraw::Alignment)
virtual void draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const override
Draw the scale.
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &) override
Update the item to changes of the axes scale division.

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 ()
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
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 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

Additional Inherited Members

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.
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

Protected Member Functions inherited from QwtPlotItem

QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const
Return a default icon from a brush.

Detailed Description

A class which draws a scale inside the plot canvas.

QwtPlotScaleItem can be used to draw an axis inside the plot canvas. It might by synchronized to one of the axis of the plot, but can also display its own ticks and labels.

It is allowed to synchronize the scale item with a disabled axis. In plots with vertical and horizontal scale items, it might be necessary to remove ticks at the intersections, by overloading updateScaleDiv().

The scale might be at a specific position (f.e 0.0) or it might be aligned to a canvas border.

Example

The following example shows how to replace the left axis, by a scale item at the x position 0.0.

QwtPlotScaleItem *scaleItem = new QwtPlotScaleItem( QwtScaleDraw::RightScale, 0.0 );
scaleItem−>setFont( plot−>axisWidget( QwtAxis::YLeft )−>font() );
scaleItem−>attach(plot);

plot−>setAxisVisible( QwtAxis::YLeft, false );

Definition at line 46 of file qwt_plot_scaleitem.h.

Constructor & Destructor Documentation

QwtPlotScaleItem::QwtPlotScaleItem (QwtScaleDraw::Alignment alignment =QwtScaleDraw::BottomScale, const double pos = 0.0) [explicit]

Constructor for scale item at the position pos.

Parameters

alignment In case of QwtScaleDraw::BottomScale or QwtScaleDraw::TopScale the scale item is corresponding to the xAxis(), otherwise it corresponds to the yAxis().
pos x or y position, depending on the corresponding axis.

See also

setPosition(), setAlignment()

Definition at line 75 of file qwt_plot_scaleitem.cpp.

QwtPlotScaleItem::˜QwtPlotScaleItem () [virtual]

Destructor.

Definition at line 88 of file qwt_plot_scaleitem.cpp.

Member Function Documentation

int QwtPlotScaleItem::borderDistance () const

Returns

Distance from a canvas border

See also

setBorderDistance(), setPosition()

Returns

QwtPlotItem::Rtti_PlotScale

Reimplemented from QwtPlotItem.

Change the alignment of the scale

The alignment sets the orientation of the scale and the position of the ticks:

	•		QwtScaleDraw::BottomScale: horizontal, ticks below
	•		QwtScaleDraw::TopScale: horizontal, ticks above
	•		QwtScaleDraw::LeftScale: vertical, ticks left
	•		QwtScaleDraw::RightScale: vertical, ticks right

For horizontal scales the position corresponds to QwtPlotItem::yAxis(), otherwise to QwtPlotItem::xAxis().

See also

scaleDraw(), QwtScaleDraw::alignment(), setPosition()

Definition at line 333 of file qwt_plot_scaleitem.cpp.

void QwtPlotScaleItem::setBorderDistance (int distance)

Align the scale to the canvas. If distance is >= 0 the scale will be aligned to a border of the contents rectangle of the canvas. If alignment() is QwtScaleDraw::LeftScale, the scale will be aligned to the right border, if it is QwtScaleDraw::TopScale it will be aligned to the bottom (and vice versa),

If distance is < 0 the scale will be at the position().

Parameters

distance Number of pixels between the canvas border and the backbone of the scale.

See also

setPosition(), borderDistance()

Definition at line 296 of file qwt_plot_scaleitem.cpp.

void QwtPlotScaleItem::setFont (const QFont & font)

Change the tick label font

See also

font()

Definition at line 183 of file qwt_plot_scaleitem.cpp.

void QwtPlotScaleItem::setPalette (const QPalette & palette)

Set the palette

See also

QwtAbstractScaleDraw::draw(), palette()

Definition at line 159 of file qwt_plot_scaleitem.cpp.

void QwtPlotScaleItem::setPosition (double pos)

Change the position of the scale

The position is interpreted as y value for horizontal axes and as x value for vertical axes.

The border distance is set to -1.

Parameters

pos New position

See also

position(), setAlignment()

Definition at line 261 of file qwt_plot_scaleitem.cpp.

void QwtPlotScaleItem::setScaleDiv (const QwtScaleDiv & scaleDiv)

Assign a scale division. When assigning a scaleDiv the scale division won’t be synchronized with the corresponding axis anymore.

Parameters

scaleDiv Scale division

See also

scaleDiv(), setScaleDivFromAxis(), isScaleDivFromAxis()

Definition at line 108 of file qwt_plot_scaleitem.cpp.

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Updated 2026-06-01 - jenkler.se | uex.se