- Qt 6.8
- Qt Charts
- C++ Classes
- QValueAxis
- Qt Charts | Commercial or GPLv3

# QValueAxis Class

The QValueAxis class adds values to a chart's axes. More...

Header: | #include <QValueAxis>
Instantiated By: | ValueAxis
Inherits: | QAbstractAxis
Inherited By: | QCategoryAxis

- List of all members, including inherited members

## Public Types

enum | TickType { TicksDynamic, TicksFixed }

## Properties

labelFormat : QString max : qreal min : qreal minorTickCount : int | tickAnchor : qreal tickCount : int tickInterval : qreal tickType : TickType

## Public Functions

| QValueAxis(QObject *parent = nullptr)
virtual | ~QValueAxis()
QString | labelFormat() const
qreal | max() const
qreal | min() const
int | minorTickCount() const
void | setLabelFormat(const QString &format)
void | setMax(qreal max)
void | setMin(qreal min)
void | setMinorTickCount(int count)
void | setRange(qreal min, qreal max)
void | setTickAnchor(qreal anchor)
void | setTickCount(int count)
void | setTickInterval(qreal insterval)
void | setTickType(QValueAxis::TickType type)
qreal | tickAnchor() const
int | tickCount() const
qreal | tickInterval() const
QValueAxis::TickType | tickType() const

## Reimplemented Public Functions

virtual QAbstractAxis::AxisType | type() const override

## Public Slots

void | applyNiceNumbers()

## Signals

void | labelFormatChanged(const QString &format)
void | maxChanged(qreal max)
void | minChanged(qreal min)
void | minorTickCountChanged(int minorTickCount)
void | rangeChanged(qreal min, qreal max)
void | tickAnchorChanged(qreal anchor)
void | tickCountChanged(int tickCount)
void | tickIntervalChanged(qreal interval)
void | tickTypeChanged(QValueAxis::TickType type)

## Detailed Description

A 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.

The following example code illustrates how to use the QValueAxis class:

     QChartView *chartView = new QChartView;
     QLineSeries *series = new QLineSeries;
     // ...
     chartView->chart()->addSeries(series);

     QValueAxis *axisX = new QValueAxis;
     axisX->setRange(10, 20.5);
     axisX->setTickCount(10);
     axisX->setLabelFormat("%.2f");
     chartView->chart()->setAxisX(axisX, series);

## Member Type Documentation

### enum QValueAxis::TickType

This enum describes how the ticks and labels are positioned on the axis.

Constant | Value | Description
--- | --- | ---
`QValueAxis::TicksDynamic` | `0` | Ticks are placed according to tickAnchor and tickInterval values.
`QValueAxis::TicksFixed` | `1` | Ticks are placed evenly across the axis range. The tickCount value specifies the number of ticks.

## Property Documentation

### 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.

If QChart::localizeNumbers is `true`, the supported specifiers are limited to: d, e, E, f, g, G, and i. Also, only the precision modifier is supported. The rest of the formatting comes from the default QLocale of the application.

Access functions:

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

Notifier signal:

void | labelFormatChanged(const QString &format)

See also QString::asprintf().

### 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.

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.

Access functions:

qreal | min() const
void | setMin(qreal min)

Notifier signal:

void | minChanged(qreal min)

### minorTickCount : int

This property holds the number of minor tick marks on the axis. This indicates how many grid lines are drawn between major ticks on the chart. Labels are not drawn for minor ticks. The default value is 0.

Access functions:

int | minorTickCount() const
void | setMinorTickCount(int count)

Notifier signal:

void | minorTickCountChanged(int minorTickCount)

### tickAnchor : qreal

This property holds the base value where the dynamically placed tick marks and labels are started from.

Access functions:

qreal | tickAnchor() const
void | setTickAnchor(qreal anchor)

Notifier signal:

void | tickAnchorChanged(qreal anchor)

### tickCount : int

This property holds the number of tick marks on the axis. This indicates how many grid lines are drawn on the chart. The default value is 5, and the number cannot be less than 2.

Access functions:

int | tickCount() const
void | setTickCount(int count)

Notifier signal:

void | tickCountChanged(int tickCount)

### tickInterval : qreal

This property holds the interval between dynamically placed tick marks and labels.

Access functions:

qreal | tickInterval() const
void | setTickInterval(qreal insterval)

Notifier signal:

void | tickIntervalChanged(qreal interval)

### tickType : TickType

This property holds the positioning method of tick and labels.

Access functions:

QValueAxis::TickType | tickType() const
void | setTickType(QValueAxis::TickType type)

Notifier signal:

void | tickTypeChanged(QValueAxis::TickType type)

## Member Function Documentation

### `[explicit]` QValueAxis::QValueAxis(QObject *parent = nullptr)

Constructs an axis object that is a child of parent.

### `[virtual noexcept]` QValueAxis::~QValueAxis()

Destroys the object.

### `[slot]` void QValueAxis::applyNiceNumbers()

Modifies the current range and number of tick marks on the axis to look nice. The algorithm considers numbers that can be expressed as a form of 1*10^n, 2* 10^n, or 5*10^n to be nice numbers. These numbers are used for setting spacing for the tick marks.

See also setRange() and setTickCount().

### `[signal]` void QValueAxis::labelFormatChanged(const QString &format)

This signal is emitted when the format of axis labels changes.

Note: Notifier signal for property labelFormat.

### `[signal]` void QValueAxis::maxChanged(qreal max)

This signal is emitted when the maximum value of the axis, specified by max, changes.

Note: Notifier signal for property max.

### `[signal]` void QValueAxis::minChanged(qreal min)

This signal is emitted when the minimum value of the axis, specified by min, changes.

Note: Notifier signal for property min.

### `[signal]` void QValueAxis::minorTickCountChanged(int minorTickCount)

This signal is emitted when the number of minor tick marks on the axis, specified by minorTickCount, changes.

Note: Notifier signal for property minorTickCount.

### `[signal]` void QValueAxis::rangeChanged(qreal min, qreal max)

This signal is emitted when the minimum or maximum value of the axis, specified by min and max, changes.

### void QValueAxis::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.

### `[signal]` void QValueAxis::tickCountChanged(int tickCount)

This signal is emitted when the number of tick marks on the axis, specified by tickCount, changes.

Note: Notifier signal for property tickCount.

### `[override virtual]` QAbstractAxis::AxisType QValueAxis::type() const

Reimplements: QAbstractAxis::type() const.

Returns the type of the axis.