QMetaDataReaderControl Class
The QMetaDataReaderControl class provides read access to the meta-data of a QMediaService's media. More...
| Header: | #include <QMetaDataReaderControl> |
| qmake: | QT += multimedia |
| Inherits: | QMediaControl |
This class is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code.
Public Functions
| virtual | ~QMetaDataReaderControl() |
| virtual QStringList | availableMetaData() const = 0 |
| virtual bool | isMetaDataAvailable() const = 0 |
| virtual QVariant | metaData(const QString &key) const = 0 |
Signals
| void | metaDataAvailableChanged(bool available) |
| void | metaDataChanged(const QString &key, const QVariant &value) |
| void | metaDataChanged() |
Protected Functions
| QMetaDataReaderControl(QObject *parent = nullptr) |
Macros
Detailed Description
If a QMediaService can provide read or write access to the meta-data of its current media it will implement QMetaDataReaderControl. This control provides functions for both retrieving and setting meta-data values. Meta-data may be addressed by the keys defined in the QMediaMetaData namespace.
The functionality provided by this control is exposed to application code by the meta-data members of QMediaObject, and so meta-data access is potentially available in any of the media object classes. Any media service may implement QMetaDataReaderControl.
The interface name of QMetaDataReaderControl is org.qt-project.qt.metadatareadercontrol/5.0 as defined in QMetaDataReaderControl_iid.
See also QMediaService::requestControl() and QMediaObject.
Member Function Documentation
[protected] QMetaDataReaderControl::QMetaDataReaderControl(QObject *parent = nullptr)
Construct a QMetaDataReaderControl with parent. This class is meant as a base class for service specific meta data providers so this constructor is protected.
[signal] void QMetaDataReaderControl::metaDataAvailableChanged(bool available)
Signal the availability of meta-data has changed, available will be true if the multimedia object has meta-data.
[signal] void QMetaDataReaderControl::metaDataChanged(const QString &key, const QVariant &value)
Signal the changes of one meta-data element value with the given key.
Note: Signal metaDataChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:
connect(metaDataReaderControl, QOverload<const QString &, const QVariant &>::of(&QMetaDataReaderControl::metaDataChanged), [=](const QString &key, const QVariant &value){ /* ... */ });
[signal] void QMetaDataReaderControl::metaDataChanged()
Signal the changes of meta-data.
If multiple meta-data elements are changed, metaDataChanged(const QString &key, const QVariant &value) signal is emitted for each of them with metaDataChanged() changed emitted once.
Note: Signal metaDataChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:
connect(metaDataReaderControl, QOverload<>::of(&QMetaDataReaderControl::metaDataChanged), [=](){ /* ... */ });
[virtual] QMetaDataReaderControl::~QMetaDataReaderControl()
Destroy the meta-data object.
[pure virtual] QStringList QMetaDataReaderControl::availableMetaData() const
Returns a list of keys there is meta-data available for.
[pure virtual] bool QMetaDataReaderControl::isMetaDataAvailable() const
Identifies if meta-data is available from a media service.
Returns true if the meta-data is available and false otherwise.
[pure virtual] QVariant QMetaDataReaderControl::metaData(const QString &key) const
Returns the meta-data for the given key.
Macro Documentation
QMetaDataReaderControl_iid
org.qt-project.qt.metadatareadercontrol/5.0
Defines the interface name of the QMetaDataReaderControl class.