QMetaDataReaderControl Class

The QMetaDataReaderControl class provides read access to the meta-data of a QMediaService 's media. 更多...

頭：	#include <QMetaDataReaderControl>
qmake:	QT += multimedia
繼承：	QMediaControl

該類已過時。 提供它是為使舊源代碼能繼續工作。強烈建議不要在新代碼中使用它。

• 所有成員列錶，包括繼承成員

公共函數

virtual	~QMetaDataReaderControl ()
virtual QStringList	availableMetaData () const = 0
virtual bool	isMetaDataAvailable () const = 0
virtual QVariant	metaData (const QString & key ) const = 0

信號

void	metaDataAvailableChanged (bool available )
void	metaDataChanged (const QString & key , const QVariant & value )
void	metaDataChanged ()

保護函數

QMetaDataReaderControl (QObject * parent = nullptr)

宏

QMetaDataReaderControl_iid

詳細描述

若 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 名稱空間。

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 作為定義在 QMetaDataReaderControl_iid .

另請參閱 QMediaService::requestControl () 和 QMediaObject .

成員函數文檔編製

[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 采用給定 key .

注意： 信號 metaDataChanged 在此類中被重載。通過使用函數指針句法連接到此信號，Qt 提供用於獲得如此範例展示的函數指針的方便幫助程序：

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.

注意： 信號 metaDataChanged 在此類中被重載。通過使用函數指針句法連接到此信號，Qt 提供用於獲得如此範例展示的函數指針的方便幫助程序：

connect(metaDataReaderControl, QOverload<>::of(&QMetaDataReaderControl::metaDataChanged),
    [=](){ /* ... */ });
					

[虛擬] QMetaDataReaderControl:: ~QMetaDataReaderControl ()

Destroy the meta-data object.

[pure virtual] QStringList QMetaDataReaderControl:: availableMetaData () const

返迴元數據的可用鍵列錶。

[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 .

宏文檔編製

QMetaDataReaderControl_iid

org.qt-project.qt.metadatareadercontrol/5.0

定義接口名為 QMetaDataReaderControl 類。

內容

1. 公共函數

2. 信號

3. 保護函數

4. 宏

5. 詳細描述