Xmp VB.NET Reference Documentation

Xmp

Current Version: 9.5.0.73

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

Object Creation

Dim obj As New Chilkat.Xmp()

Properties

DebugLogFilePath
DebugLogFilePath As String

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
LastErrorHtml As String (ReadOnly)

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
LastErrorText As String (ReadOnly)

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
LastErrorXml As String (ReadOnly)

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
LastMethodSuccess As Boolean
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
NumEmbedded As Integer (ReadOnly)

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

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StructInnerDescrip
StructInnerDescrip As Boolean

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

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VerboseLogging
VerboseLogging As Boolean

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
Version As String (ReadOnly)

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

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Methods

AddArray
Function AddArray(ByVal xml As Xml, ByVal arrType As String, ByVal propName As String, ByVal values As StringArray) As Boolean

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
Sub AddNsMapping(ByVal ns As String, ByVal uri As String)

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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AddSimpleDate
Function AddSimpleDate(ByVal iXml As Xml, ByVal propName As String, ByVal propVal As Date) As Boolean
This method is deprecated. It will be removed in a future version.

Adds or replaces an XMP date 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 "xap:CreateDate".

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AddSimpleInt
Function AddSimpleInt(ByVal iXml As Xml, ByVal propName As String, ByVal propVal As Integer) As Boolean

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
Function AddSimpleStr(ByVal iXml As Xml, ByVal propName As String, ByVal propVal As String) As Boolean

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
Function AddStructProp(ByVal iChilkatXml As Xml, ByVal structName As String, ByVal propName As String, ByVal propValue As String) As Boolean

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
Function Append(ByVal iXml As Xml) As Boolean

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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DateToString
Function DateToString(ByVal d As Date) As String
This method is deprecated. It will be removed in a future version.

Converts a date to a string representation. This method is added for convenience (just in case date-to-string conversions are required).

Returns Nothing on failure

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GetArray
Function GetArray(ByVal iXml As Xml, ByVal propName As String) As StringArray

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

Returns Nothing on failure

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GetEmbedded
Function GetEmbedded(ByVal index As Integer) As Xml

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

Returns Nothing on failure

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GetProperty
Function GetProperty(ByVal iXml As Xml, ByVal propName As String) As Xml

To be documented soon...

Returns Nothing on failure

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GetSimpleDate
Function GetSimpleDate(ByVal iXml As Xml, ByVal propName As String) As Date
This method is deprecated. It will be removed in a future version.

Finds and returns an XMP date property. The property name should be prefixed with the namespace, such as "xap:ModifyDate".

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GetSimpleInt
Function GetSimpleInt(ByVal iXml As Xml, ByVal propName As String) As Integer

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
Function GetSimpleStr(ByVal iXml As Xml, ByVal propName As String) As String

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

Returns Nothing on failure

More Information and Examples
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GetStructPropNames
Function GetStructPropNames(ByVal iXml As Xml, ByVal structName As String) As StringArray

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 Nothing on failure

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GetStructValue
Function GetStructValue(ByVal iXml As Xml, ByVal structName As String, ByVal propName As String) As String

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

Returns Nothing on failure

More Information and Examples
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LoadAppFile
Function LoadAppFile(ByVal filename As String) As Boolean

Loads a TIFF or JPG file into the XMP object.

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LoadFromBuffer
Function LoadFromBuffer(ByVal fileData As Byte(), ByVal ext As String) As Boolean

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

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NewXmp
Function NewXmp() As Xml

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

Returns Nothing on failure

More Information and Examples
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RemoveAllEmbedded
Function RemoveAllEmbedded() As Boolean

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
Function RemoveArray(ByVal iXml As Xml, ByVal propName As String) As Boolean

Removes an XMP array property from the XMP document.

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RemoveEmbedded
Function RemoveEmbedded(ByVal index As Integer) As Boolean

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
Sub RemoveNsMapping(ByVal ns As String)

Removes a namespace-to-URI mapping.

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RemoveSimple
Function RemoveSimple(ByVal iXml As Xml, ByVal propName As String) As Boolean

Removes a simple XMP property from the XMP document.

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RemoveStruct
Function RemoveStruct(ByVal iXml As Xml, ByVal structName As String) As Boolean

Removes an XMP structure property from the XMP document.

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RemoveStructProp
Function RemoveStructProp(ByVal iXml As Xml, ByVal structName As String, ByVal propName As String) As Boolean

Removes a single member from an XMP structured property.

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SaveAppFile
Function SaveAppFile(ByVal filename As String) As Boolean

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
Function SaveLastError(ByVal path As String) As Boolean

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
Function SaveToBuffer() As Byte()

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

Returns an empty byte array on failure

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StringToDate
Function StringToDate(ByVal str As String) As Date
This method is deprecated. It will be removed in a future version.

Converts a string to a date value. This method is added for convenience (just in case string-to-date conversions are required).

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UnlockComponent
Function UnlockComponent(ByVal unlockCode As String) As Boolean

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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