- Qt 6.9
- Qt Charts
- C++ Classes
- QVBarModelMapper
- Qt Charts | Commercial or GPLv3

# QVBarModelMapper Class

The QVBarModelMapper class is a vertical model mapper for bar series. More...

Header: | `#include <QVBarModelMapper>`
In QML: | VBarModelMapper

- List of all members, including inherited members

## Properties

- firstBarSetColumn : int
- firstRow : int
- lastBarSetColumn : int

- model : QAbstractItemModel*
- rowCount : int
- series : QAbstractBarSeries*

## Public Functions

| QVBarModelMapper(QObject *parent = nullptr)
int | firstBarSetColumn() const
int | firstRow() const
int | lastBarSetColumn() const
QAbstractItemModel * | model() const
int | rowCount() const
QAbstractBarSeries * | series() const
void | setFirstBarSetColumn(int firstBarSetColumn)
void | setFirstRow(int firstRow)
void | setLastBarSetColumn(int lastBarSetColumn)
void | setModel(QAbstractItemModel *model)
void | setRowCount(int rowCount)
void | setSeries(QAbstractBarSeries *series)

## Signals

void | firstBarSetColumnChanged()
void | firstRowChanged()
void | lastBarSetColumnChanged()
void | modelReplaced()
void | rowCountChanged()
void | seriesReplaced()

## Detailed Description

Model mappers enable using a data model derived from the QAbstractItemModel class as a data source for a chart. A vertical model mapper is used to create a connection between a data model and QAbstractBarSeries, so that each column in the data model defines a bar set and each row maps to a category in a bar series.

Both model and bar series properties can be used to manipulate the data. The model mapper keeps the bar series and the data model in sync.

The model mapper ensures that all the bar sets in the bar series have equal sizes. Therefore, adding or removing a value from a bar set causes the same change to be made in all the bar sets in the bar series.

For more information, see Charts with Widgets Gallery.

See also QHBarModelMapper.

## Property Documentation

### firstBarSetColumn : int

This property holds the column of the model that is used as the data source for the first bar set.

The default value is -1 (invalid mapping).

Access functions:

int | firstBarSetColumn() const
void | setFirstBarSetColumn(int firstBarSetColumn)

Notifier signal:

void | firstBarSetColumnChanged()

### firstRow : int

This property holds the row of the model that contains the first values of the bar sets in the bar series.

The minimum and default value is 0.

Access functions:

int | firstRow() const
void | setFirstRow(int firstRow)

Notifier signal:

void | firstRowChanged()

### lastBarSetColumn : int

This property holds the column of the model that is used as the data source for the last bar set.

The default value is -1 (invalid mapping).

Access functions:

int | lastBarSetColumn() const
void | setLastBarSetColumn(int lastBarSetColumn)

Notifier signal:

void | lastBarSetColumnChanged()

### model : QAbstractItemModel*

This property holds the data model that is used by the mapper.

Access functions:

QAbstractItemModel * | model() const
void | setModel(QAbstractItemModel *model)

Notifier signal:

void | modelReplaced()

### rowCount : int

This property holds the number of rows of the model that are mapped as the data for the bar series.

The minimum and default value is -1 (number limited to the number of rows in the model).

Access functions:

int | rowCount() const
void | setRowCount(int rowCount)

Notifier signal:

void | rowCountChanged()

### series : QAbstractBarSeries*

This property holds the bar series that is used by the mapper.

All the data in the series is discarded when it is set to the mapper. When a new series is specified, the old series is disconnected (but it preserves its data).

Access functions:

QAbstractBarSeries * | series() const
void | setSeries(QAbstractBarSeries *series)

Notifier signal:

void | seriesReplaced()

## Member Function Documentation

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

Constructs a mapper object that is a child of parent.

### `[signal]` void QVBarModelMapper::firstBarSetColumnChanged()

This signal is emitted when the first bar set column changes.

Note: Notifier signal for property firstBarSetColumn.

### `[signal]` void QVBarModelMapper::firstRowChanged()

This signal is emitted when the first row changes.

Note: Notifier signal for property firstRow.

### `[signal]` void QVBarModelMapper::lastBarSetColumnChanged()

This signal is emitted when the last bar set column changes.

Note: Notifier signal for property lastBarSetColumn.

### `[signal]` void QVBarModelMapper::modelReplaced()

This signal is emitted when the model that the mapper is connected to changes.

Note: Notifier signal for property model.

### `[signal]` void QVBarModelMapper::rowCountChanged()

This signal is emitted when the number of rows changes.

Note: Notifier signal for property rowCount.

### `[signal]` void QVBarModelMapper::seriesReplaced()

This signal is emitted when the bar series that the mapper is connected to changes.

Note: Notifier signal for property series.