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IWMDMMetaData::QueryByName

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The QueryByName method retrieves the value of a property by specifying its name.

Syntax

HRESULT QueryByName(
  LPCWSTR  pwszTagName,
  WMDM_TAG_DATATYPE*  pType,
  BYTE**  pValue,
  UINT*  pcbLength
);

Parameters

pwszTagName

[in]  Pointer to a wide-character null-terminated string containing the name.

pType

[out]  Pointer to a variable containing one member of the WMDM_TAG_DATATYPE enumeration type.

pValue

[out]  Pointer to a pointer to a byte array that receives the content of the value if the method succeeds. The caller must free the memory through the CoTaskMemFree method.

pcbLength

[out]  Pointer to the size, in bytes, of the byte array ppValue.

Return Values

The method returns an HRESULT. All the interface methods in Windows Media Device Manager and service provider can return any of the following classes of error codes:

  • Standard COM error codes
  • Windows error codes converted to HRESULT values
  • Windows Media Device Manager error codes

For a complete list of possible error codes, see Error Codes.

Possible values include, but are not limited to, those in the following table.

Value Description
S_OK The method succeeded.
E_OUTOFMEMORY There is not enough memory to allocate the item.
E_INVALIDARG One or more parameters are invalid.

Example Code

// Assume that the parameter pMetaData is a valid IWMDMMetaData.
    WMDM_TAG_DATATYPE type;
    BYTE *value;
    UINT size;
    HRESULT hr;

// Get album information.
  hr  = pMetaData->QueryByName(g_wszWMDMAlbumTitle, &type, &value, &size);
  if(SUCCEEDED(hr) && size)
   {
    // Do something with value and then free it.
    CoTaskMemFree(value);
   }

Requirements

Header: Defined in wmdm.idl.

Library: mssachlp.lib

See Also