IOpcSignatureCustomObject::GetXml method (msopc.h)

Article
2021-10-13

Gets the XML markup of an application-specific Object element.

Syntax

HRESULT GetXml(
  [out] UINT8  **xmlMarkup,
  [out] UINT32 *count
);

Parameters

[out] xmlMarkup

A pointer to a buffer that contains the XML markup of an Object element and includes the opening and closing Object tags.

In the buffer, XML markup is preceded by a byte order mark that corresponds to the encoding of the markup.

Supported encodings and byte order mark values.

Encoding	Description	Byte order mark
UTF8	UTF-8	EF BB BF
UTF16LE	UTF-16, little endian	FF FE
UTF16BE	UTF-16, big endian	FE FF

For an example of a buffer with a byte order mark, see the Remarks section.

[out] count

A pointer to the size of the xmlMarkup buffer.

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code	Description
S_OK	The method succeeded.
E_POINTER	At least one of the xmlMarkup, and count parameters is NULL.

Remarks

This method allocates memory used by the buffer returned in xmlMarkup. If the method succeeds, call the CoTaskMemFree function to free the memory.

Serialized application-specific Object elements in signature markup can be added, removed, or modified by replacing the signature markup.

To replace signature markup, call the IOpcDigitalSignatureManager::ReplaceSignatureXml method. The caller must ensure that addition, deletion, or modification of application-specific Object elements does not break the signature.

To sign an application-specific Object element or a child of that element, create a reference to the XML element to be signed. Create the reference by calling the IOpcSignatureReferenceSet::Create method with the referenceUri parameter value set to "#" followed by the Id attribute value of the referenced element. For example, if the Id attribute of the referenced element is "Application", set referenceUri to "#Application".

The following table shows a byte order mark at the beginning of an xmlMarkup buffer that contains "<Object Id="id1"></Object>":

Buffer Byte Index	0	1	2	3	4	5	6	7	...
UTF8 Value	EF	BB	BF	'<'	'O'	'b'	'j'	'e'	...
UTF16LE Value	FF	FE	'<'	00	'O'	00	'b'	00	...

Thread Safety

Packaging objects are not thread-safe.

For more information, see the Getting Started with the Packaging API.

Requirements

Requirement	Value
Minimum supported client	Windows 7 [desktop apps only]
Minimum supported server	Windows Server 2008 R2 [desktop apps only]
Target Platform	Windows
Header	msopc.h

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