DataChangeFilter Class | Qt OPC UA 6.4.1

- Qt 6.4
- Qt OPC UA
- C++ Classes
- DataChangeFilter
- Qt 6.4.1 Reference Documentation

# DataChangeFilter Class

class QOpcUaMonitoringParameters::DataChangeFilter

Defines a DataChangeFilter for a monitored item. More...

- List of all members, including inherited members

## Public Types

enum class | DataChangeTrigger { Status, StatusOrValue, StatusOrValueOrTimestamp }
enum class | DeadbandType { None, Absolute, Percent }

## Public Functions

| DataChangeFilter(DataChangeFilter::DataChangeTrigger trigger, DataChangeFilter::DeadbandType deadbandType, double deadbandValue)
| DataChangeFilter(const DataChangeFilter &rhs)
| DataChangeFilter()
DataChangeFilter & | operator=(const DataChangeFilter &rhs)
DataChangeFilter::DeadbandType | deadbandType() const
double | deadbandValue() const
void | setDeadbandType(DataChangeFilter::DeadbandType deadbandType)
void | setDeadbandValue(double deadbandValue)
void | setTrigger(DataChangeFilter::DataChangeTrigger trigger)
DataChangeFilter::DataChangeTrigger | trigger() const
QVariant | operator QVariant() const
bool | operator==(const DataChangeFilter &rhs) const

## Detailed Description

This class is used to set up filtering for a DataChange monitored item. It is defined in OPC-UA part 4, 7.12.2.

## Member Type Documentation

### enum class DataChangeFilter::DataChangeTrigger

Enumerates the possible triggers for a DataChangeFilter.

Constant | Value | Description
--- | --- | ---
`QOpcUaMonitoringParameters::DataChangeFilter::DataChangeTrigger::Status` | `0` | Triggers if the value's status code changes.
`QOpcUaMonitoringParameters::DataChangeFilter::DataChangeTrigger::StatusOrValue` | `1` | Triggers if the value's status code or the value itself changes.
`QOpcUaMonitoringParameters::DataChangeFilter::DataChangeTrigger::StatusOrValueOrTimestamp` | `2` | Triggers if the value's status code, the value itself or the source timestamp changes.

### enum class DataChangeFilter::DeadbandType

Enumerates the possible deadband types for a DataChangeFilter.

Constant | Value | Description
--- | --- | ---
`QOpcUaMonitoringParameters::DataChangeFilter::DeadbandType::None` | `0` | No deadband filtering.
`QOpcUaMonitoringParameters::DataChangeFilter::DeadbandType::Absolute` | `1` | A notification is generated if the absolute value of the difference between the last cached value and the current value is greater than the deadband value.
`QOpcUaMonitoringParameters::DataChangeFilter::DeadbandType::Percent` | `2` | Only valid for AnalogItems with an EURange property. A notification is generated if the absolute value of the difference between the last cached value and the current value is greater than value percent of the EURange.

## Member Function Documentation

### DataChangeFilter::DataChangeFilter(DataChangeFilter::DataChangeTrigger trigger, DataChangeFilter::DeadbandType deadbandType, double deadbandValue)

Constructs a data change filter with trigger trigger, deadband type deadbandType and deadband value deadbandValue.

### DataChangeFilter::DataChangeFilter(const DataChangeFilter &rhs)

Constructs a data change filter from rhs.

### DataChangeFilter::DataChangeFilter()

Constructs a data change filter with trigger on `status`, deadband type `none` and deadbandValue `0`.

### DataChangeFilter &DataChangeFilter::operator=(const DataChangeFilter &rhs)

Sets the values from rhs in this data change filter.

### DataChangeFilter::DeadbandType DataChangeFilter::deadbandType() const

Returns the deadband type.

See also setDeadbandType().

### double DataChangeFilter::deadbandValue() const

Returns the deadband value.

See also setDeadbandValue().

### void DataChangeFilter::setDeadbandType(DataChangeFilter::DeadbandType deadbandType)

Sets the deadband type to deadbandType.

See also deadbandType().

### void DataChangeFilter::setDeadbandValue(double deadbandValue)

Sets the deadband value to deadbandValue.

See also deadbandValue().

### void DataChangeFilter::setTrigger(DataChangeFilter::DataChangeTrigger trigger)

Sets the trigger to trigger.

See also trigger().

### DataChangeFilter::DataChangeTrigger DataChangeFilter::trigger() const

Returns the trigger.

See also setTrigger().

### QVariant DataChangeFilter::operator QVariant() const

Converts this data change filter to QVariant.

### bool DataChangeFilter::operator==(const DataChangeFilter &rhs) const

Returns `true` if this data change filter has the same value as rhs.