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QLogValueAxis Class

The QLogValueAxis class adds logarithmic values to a graph's axes. More...

Header: #include <QLogValueAxis>
CMake: find_package(Qt6 REQUIRED COMPONENTS Graphs)
target_link_libraries(mytarget PRIVATE Qt6::Graphs)
qmake: QT += graphs
Since: Qt 6.12
In QML: LogValueAxis
Inherits: QAbstractAxis

Properties

Public Functions

QLogValueAxis(QObject *parent = nullptr)
virtual ~QLogValueAxis() override
qreal base() const
QString labelFormat() const
int labelPrecision() const
qreal max() const
qreal min() const
qreal pan() const
void setBase(qreal base)
void setLabelFormat(const QString &format)
void setMax(qreal max)
void setMin(qreal min)
void setPan(qreal pan)
void setRange(qreal min, qreal max)
void setSubTickCount(qsizetype count)
void setZoom(qreal zoom)
void setlabelPrecision(int decimals)
qsizetype subTickCount() const
qsizetype tickCount() const
qreal visualMax() const
qreal visualMin() const
qreal zoom() const

Reimplemented Public Functions

virtual QAbstractAxis::AxisType type() const override

Signals

void baseChanged(qreal base)
void labelFormatChanged(const QString &format)
void labelPrecisionChanged(int precision)
void maxChanged(qreal max)
void minChanged(qreal min)
void panChanged(qreal pan)
void subTickCountChanged(qsizetype subTickCount)
void tickCountChanged(qreal tickCount)
void visualMaxChanged(qreal visualMax)
void visualMinChanged(qreal visualMin)
void zoomChanged(qreal zoom)

Detailed Description

A logarithmic value axis can be set up to show an axis line with tick marks, grid lines, and shades. The values on the axis are drawn at the positions of tick marks.

Property Documentation

base : qreal

This base of the logarithm.

The value has to be greater than 0 and cannot equal 1. The default value is 10.0

Access functions:

qreal base() const
void setBase(qreal base)

Notifier signal:

void baseChanged(qreal base)

labelFormat : QString

This property holds the label format of the axis.

The format string supports the following conversion specifiers, length modifiers, and flags provided by printf() in the standard C++ library: d, i, o, x, X, f, F, e, E, g, G, c.

The default value is empty, in which case 'f' format is used.

Access functions:

QString labelFormat() const
void setLabelFormat(const QString &format)

Notifier signal:

void labelFormatChanged(const QString &format)

See also QString::asprintf().

labelPrecision : int

This property holds the maximum number of significant digits used for showing the labels. The default value is 6. Any negative precision is ignored in favor of the default, 6.

Access functions:

int labelPrecision() const
void setlabelPrecision(int decimals)

Notifier signal:

void labelPrecisionChanged(int precision)

max : qreal

This property holds the maximum value on the axis.

When setting this property, the minimum value is adjusted if necessary, to ensure that the range remains valid. The default value is 10.0

Access functions:

qreal max() const
void setMax(qreal max)

Notifier signal:

void maxChanged(qreal max)

min : qreal

This property holds the minimum value on the axis.

When setting this property, the maximum value is adjusted if necessary, to ensure that the range remains valid. The default value is 0.0

Access functions:

qreal min() const
void setMin(qreal min)

Notifier signal:

void minChanged(qreal min)

pan : qreal

This property holds the pan value of the axis.

The pan value moves the center of the axis without affecting intervals of grid and labels. The default value is 0.

Access functions:

qreal pan() const
void setPan(qreal pan)

Notifier signal:

void panChanged(qreal pan)

subTickCount : qsizetype

This property holds the number of subticks on the axis. This indicates how many subticks are drawn between major lines on the graph. Labels are not drawn for subticks. Set the value to -1 and the number of subticks will be set equal to the closest integer value of the logarithm base. The default value is -1.

Access functions:

qsizetype subTickCount() const
void setSubTickCount(qsizetype count)

Notifier signal:

void subTickCountChanged(qsizetype subTickCount)

[read-only] tickCount : int

This property holds the number of tick marks on the axis. This value is read-only.

Access functions:

qsizetype tickCount() const

Notifier signal:

void tickCountChanged(qreal tickCount)

[read-only] visualMax : qreal

This property holds the visual maximum value of the axis.

This property holds a a visual maximum axis value when axis has been panned or zoomed. The default value is QLogValueAxis::max

Access functions:

qreal visualMax() const

Notifier signal:

void visualMaxChanged(qreal visualMax)

[read-only] visualMin : qreal

This property holds the visual minimum value of the axis.

This property holds a a visual minimum axis value when axis has been panned or zoomed. The default value is QLogValueAxis::min

Access functions:

qreal visualMin() const

Notifier signal:

void visualMinChanged(qreal visualMin)

zoom : qreal

This property holds the zoom value of the axis.

The zoom value enlarges or shrinks the axis and thus the graph without affecting intervals of grid and labels. The default value is 1.

Access functions:

qreal zoom() const
void setZoom(qreal zoom)

Notifier signal:

void zoomChanged(qreal zoom)

Member Function Documentation

[explicit] QLogValueAxis::QLogValueAxis(QObject *parent = nullptr)

Constructs an axis object that is a child of parent.

[override virtual noexcept] QLogValueAxis::~QLogValueAxis()

Destroys the object.

void QLogValueAxis::setRange(qreal min, qreal max)

Sets the range from min to max on the axis. If min is greater than max, this function returns without making any changes.

[override virtual] QAbstractAxis::AxisType QLogValueAxis::type() const

Reimplements: QAbstractAxis::type() const.

Returns the type of the axis.

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