exiv2._xmp
XMP metadatum, container and iterators.
Classes
A container for XMP data. |
|
Python wrapper for an |
|
Python wrapper for an |
|
Stateless parser class for XMP packets. |
|
Information related to an XMP property. |
- class XmpData
Bases:
SwigPyObject
A container for XMP data. This is a top-level class of the
Exiv2
library.Provide high-level access to the XMP data of an image: - read XMP information from an XML block - access metadata through keys and standard C++ iterators - add, modify and delete metadata - serialize XMP data to an XML block
- add()
Overload 1:
Add an
Xmpdatum
from the supplied key and value pair. This method copies (clones) the value.- Return type:
- Returns:
0 if successful.
Overload 2:
Add a copy of the Xmpdatum to the XMP metadata.
- Return type:
- Returns:
0 if successful.
- begin()
Begin of the metadata
- clear()
Delete all Xmpdatum instances resulting in an empty container.
- count()
Get the number of metadata entries
- empty()
Return true if there is no XMP metadata
- end()
End of the metadata
- erase()
- eraseFamily()
Delete the Xmpdatum at iterator position pos and update pos erases all following keys from the same family See: https://github.com/Exiv2/exiv2/issues/521
- findKey()
Find the first Xmpdatum with the given key, return an iterator to it.
- setPacket()
setPacket
- sortByKey()
Sort metadata by key
- usePacket()
Overload 1:
are we to use the packet?
Overload 2:
set usePacket_
- xmpPacket()
- class XmpData_iterator
Bases:
XmpData_iterator_base
Python wrapper for an
XmpData
iterator. It has most of the methods ofXmpdatum
allowing easy access to the data it points to.- copy()
Not implemented. Calling this method will raise an exception.
- count()
See
Xmpdatum.count()
.
- familyName()
- getValue()
See
Xmpdatum.getValue()
.
- groupName()
Return the (preferred) schema namespace prefix.
- key()
Return the key of the Xmpdatum. The key is of the form ‘Xmp.prefix.property’. Note however that the key is not necessarily unique, i.e., an XmpData object may contain multiple metadata with the same key.
- print()
Write the interpreted value to a string.
Implemented in terms of write(), see there.
- setValue()
See
Xmpdatum.setValue()
.
- size()
See
Xmpdatum.size()
.
- tag()
Properties don’t have a tag number. Return 0.
- tagDesc()
See
Xmpdatum.tagDesc()
.
- tagLabel()
See
Xmpdatum.tagLabel()
.
- tagName()
Return the property name.
- toFloat()
See
Xmpdatum.toFloat()
.
- toInt64()
See
Xmpdatum.toInt64()
.
- toRational()
- toString()
See
Xmpdatum.toString()
.
- toUint32()
Return the n-th component of the value converted to uint32_t.
- typeId()
See
Xmpdatum.typeId()
.
- typeName()
See
Xmpdatum.typeName()
.
- typeSize()
The Exif typeSize doesn’t make sense here. Return 0.
- value()
See
Xmpdatum.value()
.
- class XmpData_iterator_base
Bases:
SwigPyObject
Python wrapper for an
XmpData
iterator that points to the ‘end’ value and can not be dereferenced.
- class XmpParser
Bases:
SwigPyObject
Stateless parser class for XMP packets. Images use this class to parse and serialize XMP packets. The parser uses the XMP toolkit to do the job.
- exactPacketLength = 512
- includeThumbnailPad = 256
- static initialize()
Initialize the XMP Toolkit.
Calling this method is usually not needed, as encode() and decode() will initialize the XMP Toolkit if necessary.
The function takes optional pointers to a callback function xmpLockFct and related data pLockData that the parser uses when XMP namespaces are subsequently registered.
The initialize() function itself still is not thread-safe and needs to be called in a thread-safe manner (e.g., on program startup), but if used with suitable additional locking parameters, any subsequent registration of namespaces will be thread-safe.
Example usage on Windows using a critical section:
void main() { struct XmpLock { CRITICAL_SECTION cs; XmpLock() { InitializeCriticalSection(&cs); } ~XmpLock() { DeleteCriticalSection(&cs); } static void LockUnlock(void* pData, bool fLock) { XmpLock* pThis = reinterpret_cast<XmpLock*>(pData); if (pThis) { (fLock) ? EnterCriticalSection(&pThis->cs) : LeaveCriticalSection(&pThis->cs); } } } xmpLock; // Pass the locking mechanism to the XMP parser on initialization. // Note however that this call itself is still not thread-safe. Exiv2::XmpParser::initialize(XmpLock::LockUnlock, &xmpLock); // Program continues here, subsequent registrations of XMP // namespaces are serialized using xmpLock. }
- Return type:
- Returns:
True if the initialization was successful, else false.
- omitAllFormatting = 2048
- omitPacketWrapper = 16
- readOnlyPacket = 32
- static terminate()
Terminate the XMP Toolkit and unregister custom namespaces.
Call this method when the XmpParser is no longer needed to allow the XMP Toolkit to cleanly shutdown.
- useCompactFormat = 64
- writeAliasComments = 1024
- class Xmpdatum
Bases:
Metadatum
Information related to an XMP property. An XMP metadatum consists of an XmpKey and a Value and provides methods to manipulate these.
- copy()
Not implemented. Calling this method will raise an exception.
- count()
Return the number of components in the value
- familyName()
Return the name of the metadata family (which is also the first part of the key)
- getValue()
Return an auto-pointer to a copy (clone) of the value. The caller owns this copy and the auto-poiner ensures that it will be deleted.
This method is provided for users who need full control over the value. A caller may, e.g., downcast the pointer to the appropriate subclass of Value to make use of the interface of the subclass to set or modify its contents.
- Return type:
- Returns:
An auto-pointer containing a pointer to a copy (clone) of the value, 0 if the value is not set.
- groupName()
Return the (preferred) schema namespace prefix.
- key()
Return the key of the Xmpdatum. The key is of the form ‘Xmp.prefix.property’. Note however that the key is not necessarily unique, i.e., an XmpData object may contain multiple metadata with the same key.
- setValue()
Overload 1:
Set the value. This method copies (clones) the value pointed to by pValue.
Overload 2:
Set the value to the string buf. Uses Value::read(const std::string& buf). If the metadatum does not have a value yet, then one is created. See subclasses for more details. Return 0 if the value was read successfully.
- size()
Return the size of the value in bytes
- tag()
Properties don’t have a tag number. Return 0.
- tagDesc()
Return a description for the tag
- tagLabel()
Return a label for the tag
- tagName()
Return the property name.
- toFloat()
Return the n-th component of the value converted to float. The return value is -1 if the value is not set and the behaviour of the method is undefined if there is no n-th component.
- toInt64()
Return the n-th component of the value converted to int64_t. The return value is -1 if the value is not set and the behaviour of the method is undefined if there is no n-th component.
- toRational()
Return the n-th component of the value converted to Rational. The return value is -1/1 if the value is not set and the behaviour of the method is undefined if there is no n-th component.
- toString()
Overload 1:
Return the value as a string.
Overload 2:
Return the n-th component of the value converted to a string. The behaviour of the method is undefined if there is no n-th component.
- typeId()
Return the type id of the value
- typeName()
Return the name of the type
- typeSize()
The Exif typeSize doesn’t make sense here. Return 0.
- value()
Return a constant reference to the value.
This method is provided mostly for convenient and versatile output of the value which can (to some extent) be formatted through standard stream manipulators. Do not attempt to write to the value through this reference. An Error is thrown if the value is not set; as an alternative to catching it, one can use count() to check if there is any data before calling this method.
- Return type:
- Returns:
A constant reference to the value.
- Raises:
Exiv2Error
if the value is not set.