Xmp C Reference Documentation

Xmp

Current Version: 9.5.0.75

Chilkat XMP is a software component (SDK, toolkit, library, etc) for accessing, manipulating, and adding XMP metadata to JPEG and TIFF files.

Create/Dispose

HCkXmp instance = CkXmp_Create();
// ...
CkXmp_Dispose(instance);
HCkXmp CkXmp_Create(void);

Creates an instance of the HCkXmp object and returns a handle ("void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.

void CkXmp_Dispose(HCkXmp handle);

Objects created by calling CkXmp_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkXmp_Dispose.

Properties

DebugLogFilePath
void CkXmp_getDebugLogFilePath(HCkXmp cHandle, HCkString retval);
void CkXmp_putDebugLogFilePath(HCkXmp cHandle, const char *newVal);
const char *CkXmp_debugLogFilePath(HCkXmp cHandle);

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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LastErrorHtml
void CkXmp_getLastErrorHtml(HCkXmp cHandle, HCkString retval);
const char *CkXmp_lastErrorHtml(HCkXmp cHandle);

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
void CkXmp_getLastErrorText(HCkXmp cHandle, HCkString retval);
const char *CkXmp_lastErrorText(HCkXmp cHandle);

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
void CkXmp_getLastErrorXml(HCkXmp cHandle, HCkString retval);
const char *CkXmp_lastErrorXml(HCkXmp cHandle);

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
BOOL CkXmp_getLastMethodSuccess(HCkXmp cHandle);
void CkXmp_putLastMethodSuccess(HCkXmp cHandle, BOOL newVal);
Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of TRUE indicates success, a value of FALSE indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = TRUE and failure = FALSE.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to TRUE. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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NumEmbedded
int CkXmp_getNumEmbedded(HCkXmp cHandle);

The number of XMP metadata documents found within the JPG or TIFF file loaded by LoadAppFile.

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StructInnerDescrip
BOOL CkXmp_getStructInnerDescrip(HCkXmp cHandle);
void CkXmp_putStructInnerDescrip(HCkXmp cHandle, BOOL newVal);

Determines whether structures are stored with rdf:parseType="Resource", or within an "rdf:Description" sub-node.

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Utf8
BOOL CkXmp_getUtf8(HCkXmp cHandle);
void CkXmp_putUtf8(HCkXmp cHandle, BOOL newVal);

When set to TRUE, all "const char *" arguments are interpreted as utf-8 strings. If set to FALSE (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to TRUE, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to FALSE, all "const char *" return values are ANSI strings.

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VerboseLogging
BOOL CkXmp_getVerboseLogging(HCkXmp cHandle);
void CkXmp_putVerboseLogging(HCkXmp cHandle, BOOL newVal);

If set to TRUE, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is FALSE. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
void CkXmp_getVersion(HCkXmp cHandle, HCkString retval);
const char *CkXmp_version(HCkXmp cHandle);

Version of the component/library, such as "9.5.0.63"

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Methods

AddArray
BOOL CkXmp_AddArray(HCkXmp cHandle, HCkXml xml, const char *arrType, const char *propName, HCkStringArray values);

Adds or replaces an XMP property array. The XMP metadata to be updated is contained in the XML object passed in the 1st argument. The 2nd argument specifies the array type, which can be "bag", "seq", or "alt". The property name should be prefixed with the namespace, such as "dc:subject".

More Information and Examples
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AddNsMapping
void CkXmp_AddNsMapping(HCkXmp cHandle, const char *ns, const char *uri);

Adds a namespace to URI mapping. When a property is added via AddSimpleString or any of the other methods, the property name is namespace qualified. When adding the first property in a namespace, the rdf:Description is automatically added and the URI is obtained from the namespace-to-URI mappings. The standard (and commonly used) namespace mappings are defined by default. This is only used if the namespace is custom or not already handled.

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AddSimpleInt
BOOL CkXmp_AddSimpleInt(HCkXmp cHandle, HCkXml iXml, const char *propName, int propVal);

Adds or updates an XMP integer property. The XMP metadata to be updated is contained in the XML object passed in the 1st argument. The property name should be prefixed with the namespace, such as "tiff:XResolution".

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AddSimpleStr
BOOL CkXmp_AddSimpleStr(HCkXmp cHandle, HCkXml iXml, const char *propName, const char *propVal);

Adds or updates a simple XMP string property. The XMP metadata to be updated is contained in the XML object passed in the 1st argument. The property name should be prefixed with the namespace, such as "photoshop:Credit".

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AddStructProp
BOOL CkXmp_AddStructProp(HCkXmp cHandle, HCkXml iChilkatXml, const char *structName, const char *propName, const char *propValue);

Adds or updates an XMP structured property value. The XMP metadata to be updated is contained in the XML object passed in the 1st argument. The structure name should be prefixed with the namespace, such as "Iptc4xmpCore:CreatorContactInfo". The property name within the structure should also be prefixed with the namespace, such as "Iptc4xmpCore:CiAdrCity".

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Append
BOOL CkXmp_Append(HCkXmp cHandle, HCkXml iXml);

Appends a new XMP metadata file to the XMP object. Any XMPs appended via this method will be present in the file when SaveAppFile is called. Files containing XMP metadata typically only include a single XMP document, so this method is usually only called when adding XMP metadata to a file for the first time.

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GetArray
HCkStringArray CkXmp_GetArray(HCkXmp cHandle, HCkXml iXml, const char *propName);

Finds and returns an XMP array property. The property name should be prefixed with the namespace, such as "dc:subject".

Returns NULL on failure

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GetEmbedded
HCkXml CkXmp_GetEmbedded(HCkXmp cHandle, int index);

Returns the Nth embedded XMP document as a Chilkat XML object.

Returns NULL on failure

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GetProperty
HCkXml CkXmp_GetProperty(HCkXmp cHandle, HCkXml iXml, const char *propName);

To be documented soon...

Returns NULL on failure

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GetSimpleInt
int CkXmp_GetSimpleInt(HCkXmp cHandle, HCkXml iXml, const char *propName);

Finds and returns an XMP integer property. The property name should be prefixed with the namespace, such as "tiff:ResolutionUnit".

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GetSimpleStr
BOOL CkXmp_GetSimpleStr(HCkXmp cHandle, HCkXml iXml, const char *propName, HCkString outStr);
const char *CkXmp_getSimpleStr(HCkXmp cHandle, HCkXml iXml, const char *propName);

Finds and returns an XMP simple string property. The property name should be prefixed with the namespace, such as "photoshop:Source".

Returns TRUE for success, FALSE for failure.

More Information and Examples
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GetStructPropNames
HCkStringArray CkXmp_GetStructPropNames(HCkXmp cHandle, HCkXml iXml, const char *structName);

Returns the property names used by an exsting structure within an XMP document. The contents of the structure can be retrieved by calling GetStructValue for each property name returned by GetStructPropNames.

Returns NULL on failure

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GetStructValue
BOOL CkXmp_GetStructValue(HCkXmp cHandle, HCkXml iXml, const char *structName, const char *propName, HCkString outStr);
const char *CkXmp_getStructValue(HCkXmp cHandle, HCkXml iXml, const char *structName, const char *propName);

Returns the value of a single item within an XMP structure property. Property names should always be prefixed with the namespace.

Returns TRUE for success, FALSE for failure.

More Information and Examples
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LoadAppFile
BOOL CkXmp_LoadAppFile(HCkXmp cHandle, const char *filename);

Loads a TIFF or JPG file into the XMP object.

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LoadFromBuffer
BOOL CkXmp_LoadFromBuffer(HCkXmp cHandle, HCkByteData fileData, const char *ext);

Loads a JPG or TIFF from an byte buffer containing the image file data.

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NewXmp
HCkXml CkXmp_NewXmp(HCkXmp cHandle);

Creates and returns a new/empty XMP metadata document as a Chilkat XML object.

Returns NULL on failure

More Information and Examples
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RemoveAllEmbedded
BOOL CkXmp_RemoveAllEmbedded(HCkXmp cHandle);

Removes all XMP metadata documents from an XMP object. After calling this method, call SaveAppFile to rewrite the JPG or TIFF file with the XMP metadata removed.

Returns TRUE for success, FALSE for failure.

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RemoveArray
BOOL CkXmp_RemoveArray(HCkXmp cHandle, HCkXml iXml, const char *propName);

Removes an XMP array property from the XMP document.

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RemoveEmbedded
BOOL CkXmp_RemoveEmbedded(HCkXmp cHandle, int index);

Removes a single XMP metadata document from the JPG or TIFF file. Call SaveAppFile to persist the changes to disk.

Returns TRUE for success, FALSE for failure.

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RemoveNsMapping
void CkXmp_RemoveNsMapping(HCkXmp cHandle, const char *ns);

Removes a namespace-to-URI mapping.

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RemoveSimple
BOOL CkXmp_RemoveSimple(HCkXmp cHandle, HCkXml iXml, const char *propName);

Removes a simple XMP property from the XMP document.

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RemoveStruct
BOOL CkXmp_RemoveStruct(HCkXmp cHandle, HCkXml iXml, const char *structName);

Removes an XMP structure property from the XMP document.

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RemoveStructProp
BOOL CkXmp_RemoveStructProp(HCkXmp cHandle, HCkXml iXml, const char *structName, const char *propName);

Removes a single member from an XMP structured property.

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SaveAppFile
BOOL CkXmp_SaveAppFile(HCkXmp cHandle, const char *filename);

Persists all changes made to the XMP document(s) by saving the XMP object to a file. Changes made by adding, updating, or removing properties are not persisted to the filesystem until this is called.

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SaveLastError
BOOL CkXmp_SaveLastError(HCkXmp cHandle, const char *path);

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns TRUE for success, FALSE for failure.

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SaveToBuffer
BOOL CkXmp_SaveToBuffer(HCkXmp cHandle, HCkByteData outBytes);

Saves a JPG or TIFF image with updated XMP to a byte buffer.

Returns TRUE for success, FALSE for failure.

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UnlockComponent
BOOL CkXmp_UnlockComponent(HCkXmp cHandle, const char *unlockCode);

Unlocks the XMP component at runtime. This must be called once at the beginning of your application. Passing an arbitrary value initiates a fully-functional 30-day trial. A purchased unlock code is required to use the component beyond 30 days.

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