TagLib API Documentation
Public Member Functions | Static Public Member Functions | Protected Member Functions | List of all members
TagLib::ID3v2::FrameFactory Class Reference

A factory for creating ID3v2 frames during parsing. More...

#include <id3v2framefactory.h>

Public Member Functions

 FrameFactory (const FrameFactory &)=delete
 
FrameFactory & operator= (const FrameFactory &)=delete
 
virtual Frame * createFrame (const ByteVector &origData, const Header *tagHeader) const
 
virtual Frame * createFrameForProperty (const String &key, const StringList &values) const
 
virtual void rebuildAggregateFrames (ID3v2::Tag *tag) const
 
String::Type defaultTextEncoding () const
 
void setDefaultTextEncoding (String::Type encoding)
 
bool isUsingDefaultTextEncoding () const
 

Static Public Member Functions

static FrameFactory * instance ()
 

Protected Member Functions

 FrameFactory ()
 
 ~FrameFactory ()
 
virtual bool updateFrame (Frame::Header *header) const
 
std::pair< Frame::Header *, bool > prepareFrameHeader (ByteVector &data, const Header *tagHeader) const
 
virtual Frame * createFrame (const ByteVector &data, Frame::Header *header, const Header *tagHeader) const
 

Detailed Description

A factory for creating ID3v2 frames during parsing.

This factory abstracts away the frame creation process and instantiates the appropriate ID3v2::Frame subclasses based on the contents of the data.

Reimplementing this factory is the key to adding support for frame types not directly supported by TagLib to your application. To do so you would subclass this factory and reimplement createFrame(). Then by setting your factory to be the default factory in ID3v2::Tag constructor you can implement behavior that will allow for new ID3v2::Frame subclasses (also provided by you) to be used. See tests/test_id3v2framefactory.cpp for an example.

This implements both abstract factory and singleton patterns of which more information is available on the web and in software design textbooks (notably Design Patterns).

Note
You do not need to use this factory to create new frames to add to an ID3v2::Tag. You can instantiate frame subclasses directly (with new) and add them to a tag using ID3v2::Tag::addFrame()
See also
ID3v2::Tag::addFrame()

Constructor & Destructor Documentation

◆ FrameFactory() [1/2]

TagLib::ID3v2::FrameFactory::FrameFactory ( const FrameFactory &  )
delete

◆ FrameFactory() [2/2]

TagLib::ID3v2::FrameFactory::FrameFactory ( )
protected

Constructs a frame factory. Because this is a singleton this method is protected, but may be used for subclasses.

◆ ~FrameFactory()

TagLib::ID3v2::FrameFactory::~FrameFactory ( )
protected

Destroys the frame factory.

Member Function Documentation

◆ createFrame() [1/2]

virtual Frame * TagLib::ID3v2::FrameFactory::createFrame ( const ByteVector &  data,
Frame::Header *  header,
const Header *  tagHeader 
) const
protectedvirtual

Create a frame based on data. header should be a valid frame header and tagHeader a valid ID3v2::Header instance.

This method is called by the public overloaded method createFrame(const ByteVector &, const Header *) after creating header from verified data using prepareFrameHeader(), so this method is provided to be reimplemented in derived classes.

◆ createFrame() [2/2]

virtual Frame * TagLib::ID3v2::FrameFactory::createFrame ( const ByteVector &  origData,
const Header *  tagHeader 
) const
virtual

Create a frame based on origData. tagHeader should be a valid ID3v2::Header instance.

◆ createFrameForProperty()

virtual Frame * TagLib::ID3v2::FrameFactory::createFrameForProperty ( const String &  key,
const StringList &  values 
) const
virtual

Creates a textual frame which corresponds to a single key in the PropertyMap interface. TIPL and TMCL do not belong to this category and are thus handled explicitly in the Frame class.

◆ defaultTextEncoding()

String::Type TagLib::ID3v2::FrameFactory::defaultTextEncoding ( ) const

Returns the default text encoding for text frames. If setTextEncoding() has not been explicitly called this will only be used for new text frames. However, if this value has been set explicitly all frames will be converted to this type (unless it's explicitly set differently for the individual frame) when being rendered.

See also
setDefaultTextEncoding()

◆ instance()

static FrameFactory * TagLib::ID3v2::FrameFactory::instance ( )
static

◆ isUsingDefaultTextEncoding()

bool TagLib::ID3v2::FrameFactory::isUsingDefaultTextEncoding ( ) const

Returns true if defaultTextEncoding() is used. The default text encoding is used when setDefaultTextEncoding() has been called. In this case, reimplementations of FrameFactory should use defaultTextEncoding() on the frames (having a text encoding field) they create.

See also
defaultTextEncoding()
setDefaultTextEncoding()

◆ operator=()

FrameFactory & TagLib::ID3v2::FrameFactory::operator= ( const FrameFactory &  )
delete

◆ prepareFrameHeader()

std::pair< Frame::Header *, bool > TagLib::ID3v2::FrameFactory::prepareFrameHeader ( ByteVector &  data,
const Header *  tagHeader 
) const
protected

Creates and prepares the frame header for createFrame().

Parameters
datadata of the frame (might be modified)
tagHeaderthe tag header
Returns
{header, ok}: header is a created frame header or nullptr if the frame is invalid; ok is true if the frame is supported.

◆ rebuildAggregateFrames()

virtual void TagLib::ID3v2::FrameFactory::rebuildAggregateFrames ( ID3v2::Tag *  tag) const
virtual

After a tag has been read, this tries to rebuild some of them information, most notably the recording date, from frames that have been deprecated and can't be upgraded directly.

◆ setDefaultTextEncoding()

void TagLib::ID3v2::FrameFactory::setDefaultTextEncoding ( String::Type  encoding)

Set the default text encoding for all text frames that are created to encoding. If no value is set the frames with either default to the encoding type that was parsed and new frames default to Latin1.

Valid string types for ID3v2 tags are Latin1, UTF8, UTF16 and UTF16BE.

See also
defaultTextEncoding()

◆ updateFrame()

virtual bool TagLib::ID3v2::FrameFactory::updateFrame ( Frame::Header *  header) const
protectedvirtual

This method checks for compliance to the current ID3v2 standard (2.4) and does nothing in the common case. However if a frame is found that is not compatible with the current standard, this method either updates the frame or indicates that it should be discarded.

This method with return true (with or without changes to the frame) if this frame should be kept or false if it should be discarded.

See the id3v2.4.0-changes.txt document for further information.

The documentation for this class was generated from the following file: