QCategoryAxis Class

The QCategoryAxis class places named ranges on the axis. More...

Header:	#include <QCategoryAxis>
Instantiated By:	CategoryAxis
Inherits:	QValueAxis

• List of all members, including inherited members

Public Types

enum	AxisLabelsPosition { AxisLabelsPositionCenter, AxisLabelsPositionOnValue }

Properties

• categoriesLabels : const QStringList
• count : const int
• labelsPosition : AxisLabelsPosition
• startValue : qreal

Public Functions

	QCategoryAxis(QObject *parent = nullptr)
virtual	~QCategoryAxis()
void	append(const QString &categoryLabel, qreal categoryEndValue)
QStringList	categoriesLabels()
int	count() const
qreal	endValue(const QString &categoryLabel) const
QCategoryAxis::AxisLabelsPosition	labelsPosition() const
void	remove(const QString &categoryLabel)
void	replaceLabel(const QString &oldLabel, const QString &newLabel)
void	setLabelsPosition(QCategoryAxis::AxisLabelsPosition position)
void	setStartValue(qreal min)
qreal	startValue(const QString &categoryLabel = QString()) const

Reimplemented Public Functions

virtual QAbstractAxis::AxisType

type() const override

Signals

void	categoriesChanged()
void	labelsPositionChanged(QCategoryAxis::AxisLabelsPosition position)

Detailed Description

This class can be used to explain the underlying data by adding labeled categories. Unlike QBarCategoryAxis, QCategoryAxis allows the widths of the category ranges to be specified freely.

Example code on how to use QCategoryAxis:

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

QCategoryAxis *axisY = new QCategoryAxis;
axisY->setMin(0);
axisY->setMax(52);
axisY->setStartValue(15);
axisY->append("First", 20);
axisY->append("Second", 37);
axisY->append("Third", 52);
chartView->chart()->setAxisY(axisY, series);

Member Type Documentation

enum QCategoryAxis::AxisLabelsPosition

This enum describes the position of the category labels.

Constant	Value	Description
QCategoryAxis::AxisLabelsPositionCenter	0x0	Labels are centered to category.
QCategoryAxis::AxisLabelsPositionOnValue	0x1	Labels are positioned to the high end limit of the category.

Member Function Documentation

QCategoryAxis::QCategoryAxis(QObject *parent = nullptr)

Constructs an axis object that is a child of parent.

[signal] void QCategoryAxis::categoriesChanged()

This signal is emitted when the categories of the axis change.

[virtual] QCategoryAxis::~QCategoryAxis()

Destroys the object.

void QCategoryAxis::append(const QString &categoryLabel, qreal categoryEndValue)

Appends a new category to the axis with the label categoryLabel. A category label has to be unique. categoryEndValue specifies the high end limit of the category. It has to be greater than the high end limit of the previous category. Otherwise the method returns without adding a new category.

QStringList QCategoryAxis::categoriesLabels()

Returns the list of the categories' labels.

Note: Getter function for property categoriesLabels.

int QCategoryAxis::count() const

Returns the number of categories.

Note: Getter function for property count.

qreal QCategoryAxis::endValue(const QString &categoryLabel) const

Returns the high end limit of the category specified by categoryLabel.

void QCategoryAxis::remove(const QString &categoryLabel)

Removes a category specified by the label categoryLabel from the axis.

void QCategoryAxis::replaceLabel(const QString &oldLabel, const QString &newLabel)

Replaces an existing category label specified by oldLabel with newLabel. If the old label does not exist, the method returns without making any changes.

void QCategoryAxis::setStartValue(qreal min)

Sets min to be the low end limit of the first category on the axis. If categories have already been added to the axis, the passed value must be less than the high end value of the already defined first category range. Otherwise nothing is done.

Note: Setter function for property startValue.

See also startValue().

qreal QCategoryAxis::startValue(const QString &categoryLabel = QString()) const

Returns the low end limit of the category specified by categoryLabel.

Note: Getter function for property startValue.

See also setStartValue().

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

Reimplements: QValueAxis::type() const.

Returns the type of the axis.