Qt 5.7 | Qt Charts | C++ Classes | QCategoryAxis

Qt 5.7.1 Reference Documentation

# QCategoryAxis Class

The QCategoryAxis class allows putting a 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

- 5 properties inherited from QValueAxis
- 27 properties inherited from QAbstractAxis

## Public Functions

| QCategoryAxis(QObject *parent = Q_NULLPTR)
| ~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 AxisType | type() const

- 12 public functions inherited from QValueAxis
- 58 public functions inherited from QAbstractAxis

## Signals

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

- 6 signals inherited from QValueAxis
- 25 signals inherited from QAbstractAxis

### Additional Inherited Members

- 1 public slot inherited from QValueAxis

## Detailed Description

The QCategoryAxis class allows putting a named ranges on the axis.

This class can be used when the underlying data needs to be given extra meaning. Unlike with the QBarCategoryAxis the QCategoryAxis allows the categories ranges widths 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.

## Property Documentation

### categoriesLabels : const QStringList

The category labels as a string list.

Access functions:

QStringList | categoriesLabels()

### count : const int

The count of categories.

Access functions:

int | count() const

### labelsPosition : AxisLabelsPosition

Defines the position of the category labels. The labels in the beginning and in the end of the axes may overlap other axes labels when positioned on value.

Access functions:

QCategoryAxis::AxisLabelsPosition | labelsPosition() const
void | setLabelsPosition(QCategoryAxis::AxisLabelsPosition position)

Notifier signal:

void | labelsPositionChanged(QCategoryAxis::AxisLabelsPosition position)

### startValue : qreal

Defines the low end of the first category on the axis.

Access functions:

qreal | startValue(const QString &categoryLabel = QString()) const
void | setStartValue(qreal min)

## Member Function Documentation

### QCategoryAxis::QCategoryAxis(QObject *parent = Q_NULLPTR)

Constructs an axis object which is a child of parent.

### QCategoryAxis::~QCategoryAxis()

Destroys the object

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

Appends new category to the axis with an categoryLabel. Category label has to be unique. Parameter 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.

### `[signal]` void QCategoryAxis::categoriesChanged()

Axis emits signal when the categories of the axis have changed.

### QStringList QCategoryAxis::categoriesLabels()

Returns the list of the intervals labels

Note: Getter function for property categoriesLabels.

### int QCategoryAxis::count() const

Returns number of intervals.

Note: Getter function for property count.

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

Returns the high end limit of the interval specified by an categoryLabel

### void QCategoryAxis::remove(const QString &categoryLabel)

Removes an interval specified by the categoryLabel from the axis

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

Replaces oldLabel of an existing category with a 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 there is already some categories added to the axis then passed value must be lower 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 an categoryLabel

Note: Getter function for property startValue.

See also setStartValue().

### `[virtual]` AxisType QCategoryAxis::type() const

Reimplemented from QAbstractAxis::type().

Returns the type of the axis