QwtPlotRescaler - QwtPlotRescaler takes care of fixed aspect ratios for plot scales.

NAME

QwtPlotRescaler − QwtPlotRescaler takes care of fixed aspect ratios for plot scales.

SYNOPSIS

#include <qwt_plot_rescaler.h>

Inherits QObject.

Public Types

enum RescalePolicy { Fixed, Expanding, Fitting }
enum ExpandingDirection { ExpandUp, ExpandDown, ExpandBoth }

Public Member Functions

QwtPlotRescaler (QWidget *canvas, QwtAxisId referenceAxis=QwtAxis::XBottom, RescalePolicy=Expanding)
virtual ˜QwtPlotRescaler ()
Destructor.
void setEnabled (bool)
En/disable the rescaler.
bool isEnabled () const
void setRescalePolicy (RescalePolicy)
RescalePolicy rescalePolicy () const
void setExpandingDirection (ExpandingDirection)
void setExpandingDirection (QwtAxisId, ExpandingDirection)
ExpandingDirection expandingDirection (QwtAxisId) const
void setReferenceAxis (QwtAxisId)
QwtAxisId referenceAxis () const
void setAspectRatio (double ratio)
void setAspectRatio (QwtAxisId, double ratio)
double aspectRatio (QwtAxisId) const
void setIntervalHint (QwtAxisId, const QwtInterval &)
QwtInterval intervalHint (QwtAxisId) const
QWidget * canvas ()
const QWidget * canvas () const
QwtPlot * plot ()
const QwtPlot * plot () const
virtual bool eventFilter (QObject *, QEvent *) override
Event filter for the plot canvas.
void rescale () const
Adjust the plot axes scales.

Protected Member Functions

virtual void canvasResizeEvent (QResizeEvent *)
virtual void rescale (const QSize &oldSize, const QSize &newSize) const
virtual QwtInterval expandScale (QwtAxisId, const QSize &oldSize, const QSize &newSize) const
virtual QwtInterval syncScale (QwtAxisId, const QwtInterval &reference, const QSize &size) const
virtual void updateScales (QwtInterval intervals[QwtAxis::AxisPositions]) const
Qt::Orientation orientation (QwtAxisId) const
QwtInterval interval (QwtAxisId) const
QwtInterval expandInterval (const QwtInterval &, double width, ExpandingDirection) const

Detailed Description

QwtPlotRescaler takes care of fixed aspect ratios for plot scales.

QwtPlotRescaler auto adjusts the axes of a QwtPlot according to fixed aspect ratios.

Definition at line 29 of file qwt_plot_rescaler.h.

Member Enumeration Documentation

enum QwtPlotRescaler::ExpandingDirection

When rescalePolicy() is set to Expanding its direction depends on ExpandingDirection

Enumerator
ExpandUp

The upper limit of the scale is adjusted.

ExpandDown

The lower limit of the scale is adjusted.

ExpandBoth

Both limits of the scale are adjusted.

Definition at line 70 of file qwt_plot_rescaler.h.

enum QwtPlotRescaler::RescalePolicy

The rescale policy defines how to rescale the reference axis and their depending axes.

See also

ExpandingDirection, setIntervalHint()

Enumerator

Fixed

The interval of the reference axis remains unchanged, when the geometry of the canvas changes. All other axes will be adjusted according to their aspect ratio.

Expanding

The interval of the reference axis will be shrunk/expanded, when the geometry of the canvas changes. All other axes will be adjusted according to their aspect ratio.

The interval, that is represented by one pixel is fixed.
Fitting

The intervals of the axes are calculated, so that all axes include their interval hint.

Definition at line 40 of file qwt_plot_rescaler.h.

Constructor & Destructor Documentation

QwtPlotRescaler::QwtPlotRescaler (QWidget * canvas, QwtAxisId referenceAxis= QwtAxis::XBottom, RescalePolicy policy = Expanding) [explicit]

Constructor

Parameters

canvas Canvas
referenceAxis Reference axis, see RescalePolicy
policy Rescale policy

See also

setRescalePolicy(), setReferenceAxis()

Definition at line 71 of file qwt_plot_rescaler.cpp.

QwtPlotRescaler::˜QwtPlotRescaler () [virtual]

Destructor.

Definition at line 83 of file qwt_plot_rescaler.cpp.

Member Function Documentation

double QwtPlotRescaler::aspectRatio (QwtAxisId axisId) const

Returns

Aspect ratio between an axis and the reference axis.

Parameters

axisId Axis

See also

setAspectRatio()

Definition at line 243 of file qwt_plot_rescaler.cpp.

QWidget * QwtPlotRescaler::canvas ()

Returns

plot canvas

Definition at line 282 of file qwt_plot_rescaler.cpp.

const QWidget * QwtPlotRescaler::canvas () const

Returns

plot canvas

Definition at line 288 of file qwt_plot_rescaler.cpp.

void QwtPlotRescaler::canvasResizeEvent (QResizeEvent * event) [protected],[virtual]

Event handler for resize events of the plot canvas

Parameters

event Resize event

See also

rescale()

Definition at line 343 of file qwt_plot_rescaler.cpp.

bool QwtPlotRescaler::eventFilter (QObject * object, QEvent * event)[override], [virtual]

Event filter for the plot canvas.

Definition at line 314 of file qwt_plot_rescaler.cpp.

QwtPlotRescaler::ExpandingDirection QwtPlotRescaler::expandingDirection(QwtAxisId axisId) const

Returns

Direction in which an axis should be expanded

Parameters

axisId Axis

See also

setExpandingDirection()

Definition at line 197 of file qwt_plot_rescaler.cpp.

QwtInterval QwtPlotRescaler::expandInterval (const QwtInterval & interval,double width, ExpandingDirection direction) const [protected]

Expand the interval

Parameters

interval Interval to be expanded
width Distance to be added to the interval
direction Direction of the expand operation

Returns

Expanded interval

Definition at line 526 of file qwt_plot_rescaler.cpp.

QwtInterval QwtPlotRescaler::expandScale (QwtAxisId axisId, const QSize &oldSize, const QSize & newSize) const [protected], [virtual]

Calculate the new scale interval of a plot axis

Parameters

axisId Axis
oldSize Previous size of the canvas
newSize New size of the canvas

Returns

Calculated new interval for the axis

Definition at line 405 of file qwt_plot_rescaler.cpp.

QwtInterval QwtPlotRescaler::interval (QwtAxisId axisId) const [protected]

Parameters

axisId Axis

Returns

Normalized interval of an axis

Definition at line 509 of file qwt_plot_rescaler.cpp.

QwtInterval QwtPlotRescaler::intervalHint (QwtAxisId axisId) const

Parameters

axisId Axis

Returns

Interval hint

See also

setIntervalHint(), RescalePolicy

Definition at line 273 of file qwt_plot_rescaler.cpp.

bool QwtPlotRescaler::isEnabled () const

Set an interval hint for an axis

In Fitting mode, the hint is used as minimal interval that always needs to be displayed.

Parameters

axisId Axis
interval Axis

See also

intervalHint(), RescalePolicy

Definition at line 261 of file qwt_plot_rescaler.cpp.

void QwtPlotRescaler::setReferenceAxis (QwtAxisId axisId)

Set the reference axis ( see RescalePolicy )

Parameters

axisId Axis

See also

referenceAxis()

Definition at line 149 of file qwt_plot_rescaler.cpp.

void QwtPlotRescaler::setRescalePolicy (RescalePolicy policy)

Change the rescale policy

Parameters

policy Rescale policy

See also

rescalePolicy()

Definition at line 129 of file qwt_plot_rescaler.cpp.

QwtInterval QwtPlotRescaler::syncScale (QwtAxisId axisId, const QwtInterval& reference, const QSize & size) const [protected], [virtual]

Synchronize an axis scale according to the scale of the reference axis

Parameters

axisId Axis
reference Interval of the reference axis
size Size of the canvas

Returns

New interval for axis

Definition at line 469 of file qwt_plot_rescaler.cpp.

void QwtPlotRescaler::updateScales (QwtIntervalintervals[QwtAxis::AxisPositions]) const [protected], [virtual]

Update the axes scales

Parameters

intervals Scale intervals

Definition at line 588 of file qwt_plot_rescaler.cpp.

Author

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