PROPVARIANT structure (propidlbase.h)
The PROPVARIANT structure is used in the ReadMultiple and WriteMultiple methods of IPropertyStorage to define the type tag and the value of a property in a property set.
The PROPVARIANT structure is also used by the GetValue and SetValue methods of IPropertyStore, which replaces IPropertySetStorage as the primary way to program item properties in Windows Vista. For more information, see Property Handlers.
There are five members. The first member, the value-type tag, and the last member, the value of the property, are significant. The middle three members are reserved for future use.
Syntax
typedef struct tagPROPVARIANT {
union {
typedef struct {
VARTYPE vt;
PROPVAR_PAD1 wReserved1;
PROPVAR_PAD2 wReserved2;
PROPVAR_PAD3 wReserved3;
union {
CHAR cVal;
UCHAR bVal;
SHORT iVal;
USHORT uiVal;
LONG lVal;
ULONG ulVal;
INT intVal;
UINT uintVal;
LARGE_INTEGER hVal;
ULARGE_INTEGER uhVal;
FLOAT fltVal;
DOUBLE dblVal;
VARIANT_BOOL boolVal;
VARIANT_BOOL __OBSOLETE__VARIANT_BOOL;
SCODE scode;
CY cyVal;
DATE date;
FILETIME filetime;
CLSID *puuid;
CLIPDATA *pclipdata;
BSTR bstrVal;
BSTRBLOB bstrblobVal;
BLOB blob;
LPSTR pszVal;
LPWSTR pwszVal;
IUnknown *punkVal;
IDispatch *pdispVal;
IStream *pStream;
IStorage *pStorage;
LPVERSIONEDSTREAM pVersionedStream;
LPSAFEARRAY parray;
CAC cac;
CAUB caub;
CAI cai;
CAUI caui;
CAL cal;
CAUL caul;
CAH cah;
CAUH cauh;
CAFLT caflt;
CADBL cadbl;
CABOOL cabool;
CASCODE cascode;
CACY cacy;
CADATE cadate;
CAFILETIME cafiletime;
CACLSID cauuid;
CACLIPDATA caclipdata;
CABSTR cabstr;
CABSTRBLOB cabstrblob;
CALPSTR calpstr;
CALPWSTR calpwstr;
CAPROPVARIANT capropvar;
CHAR *pcVal;
UCHAR *pbVal;
SHORT *piVal;
USHORT *puiVal;
LONG *plVal;
ULONG *pulVal;
INT *pintVal;
UINT *puintVal;
FLOAT *pfltVal;
DOUBLE *pdblVal;
VARIANT_BOOL *pboolVal;
DECIMAL *pdecVal;
SCODE *pscode;
CY *pcyVal;
DATE *pdate;
BSTR *pbstrVal;
IUnknown **ppunkVal;
IDispatch **ppdispVal;
LPSAFEARRAY *pparray;
PROPVARIANT *pvarVal;
};
} tag_inner_PROPVARIANT, PROPVARIANT, *LPPROPVARIANT;
DECIMAL decVal;
};
} PROPVARIANT, *LPPROPVARIANT;
Members
tag_inner_PROPVARIANT
tag_inner_PROPVARIANT.vt
tag_inner_PROPVARIANT.wReserved1
tag_inner_PROPVARIANT.wReserved2
tag_inner_PROPVARIANT.wReserved3
tag_inner_PROPVARIANT.cVal
tag_inner_PROPVARIANT.bVal
tag_inner_PROPVARIANT.iVal
tag_inner_PROPVARIANT.uiVal
tag_inner_PROPVARIANT.lVal
tag_inner_PROPVARIANT.ulVal
tag_inner_PROPVARIANT.intVal
tag_inner_PROPVARIANT.uintVal
tag_inner_PROPVARIANT.hVal
tag_inner_PROPVARIANT.uhVal
tag_inner_PROPVARIANT.fltVal
tag_inner_PROPVARIANT.dblVal
tag_inner_PROPVARIANT.boolVal
tag_inner_PROPVARIANT.__OBSOLETE__VARIANT_BOOL
tag_inner_PROPVARIANT.scode
tag_inner_PROPVARIANT.cyVal
tag_inner_PROPVARIANT.date
tag_inner_PROPVARIANT.filetime
tag_inner_PROPVARIANT.puuid
tag_inner_PROPVARIANT.pclipdata
tag_inner_PROPVARIANT.bstrVal
tag_inner_PROPVARIANT.bstrblobVal
tag_inner_PROPVARIANT.blob
tag_inner_PROPVARIANT.pszVal
tag_inner_PROPVARIANT.pwszVal
tag_inner_PROPVARIANT.punkVal
tag_inner_PROPVARIANT.pdispVal
tag_inner_PROPVARIANT.pStream
tag_inner_PROPVARIANT.pStorage
tag_inner_PROPVARIANT.pVersionedStream
tag_inner_PROPVARIANT.parray
tag_inner_PROPVARIANT.cac
tag_inner_PROPVARIANT.caub
tag_inner_PROPVARIANT.cai
tag_inner_PROPVARIANT.caui
tag_inner_PROPVARIANT.cal
tag_inner_PROPVARIANT.caul
tag_inner_PROPVARIANT.cah
tag_inner_PROPVARIANT.cauh
tag_inner_PROPVARIANT.caflt
tag_inner_PROPVARIANT.cadbl
tag_inner_PROPVARIANT.cabool
tag_inner_PROPVARIANT.cascode
tag_inner_PROPVARIANT.cacy
tag_inner_PROPVARIANT.cadate
tag_inner_PROPVARIANT.cafiletime
tag_inner_PROPVARIANT.cauuid
tag_inner_PROPVARIANT.caclipdata
tag_inner_PROPVARIANT.cabstr
tag_inner_PROPVARIANT.cabstrblob
tag_inner_PROPVARIANT.calpstr
tag_inner_PROPVARIANT.calpwstr
tag_inner_PROPVARIANT.capropvar
tag_inner_PROPVARIANT.pcVal
tag_inner_PROPVARIANT.pbVal
tag_inner_PROPVARIANT.piVal
tag_inner_PROPVARIANT.puiVal
tag_inner_PROPVARIANT.plVal
tag_inner_PROPVARIANT.pulVal
tag_inner_PROPVARIANT.pintVal
tag_inner_PROPVARIANT.puintVal
tag_inner_PROPVARIANT.pfltVal
tag_inner_PROPVARIANT.pdblVal
tag_inner_PROPVARIANT.pboolVal
tag_inner_PROPVARIANT.pdecVal
tag_inner_PROPVARIANT.pscode
tag_inner_PROPVARIANT.pcyVal
tag_inner_PROPVARIANT.pdate
tag_inner_PROPVARIANT.pbstrVal
tag_inner_PROPVARIANT.ppunkVal
tag_inner_PROPVARIANT.ppdispVal
tag_inner_PROPVARIANT.pparray
tag_inner_PROPVARIANT.pvarVal
decVal
Remarks
The PROPVARIANT structure can also hold a value of VT_DECIMAL:
DECIMAL decVal; //VT_DECIMAL
However, the value of the DECIMAL structure requires special handling. The DECIMAL structure is the same size as an entire PROPVARIANT structure and does not fit into the union that holds all other types of values. Instead, the value of the DECIMAL structure occupies the entire PROPVARIANT structure, including the reserved fields and the vt member. However, the first member of the DECIMAL structure is not used and is equal in size to the vt member of the PROPVARIANT structure. Therefore, the PROPVARIANT structure declaration in the Propidl.h header file of Win32 defines the decVal member in such a way that it corresponds to the beginning of the PROPVARIANT structure. Therefore, to put the value of the DECIMAL structure into a PROPVARIANT structure, the value must be loaded into the decVal member and the vt member is set to VT_DECIMAL, just as for any other value.
PROPVARIANT is the fundamental data type by which property values are read and written through the IPropertyStorage interface.
The data type PROPVARIANT is related to the data type VARIANT, defined as part of Automation in OLE2. Several definitions are reused from Automation, as follows:
typedef struct tagCY {
unsigned long Lo;
long Hi;
} CY;
typedef struct tagDEC {
USHORT wReserved;
BYTE scale;
BYTE sign;
ULONG Hi32;
ULONGLONG Lo64;
} DECIMAL;
typedef struct tagSAFEARRAYBOUND {
ULONG cElements;
LONG lLbound;
} SAFEARRAYBOUND;
typedef struct tagSAFEARRAY {
USHORT cDims;
USHORT fFeatures;
ULONG cbElements;
ULONG cLocks;
PVOID pvData;
SAFEARRAYBOUND rgsabound [ * ];
} SAFEARRAY;
typedef CY CURRENCY;
typedef short VARIANT_BOOL;
typedef unsigned short VARTYPE;
typedef double DATE;
typedef OLECHAR* BSTR;
In addition, some types are unique to the PROPVARIANT structure:
typedef struct tagCLIPDATA {
// cbSize is the size of the buffer pointed to
// by pClipData, plus sizeof(ulClipFmt)
ULONG cbSize;
long ulClipFmt;
BYTE* pClipData;
} CLIPDATA;
Among the unique PROPVARIANT types are several data types that define counted arrays of other data types. The data types of all counted arrays begin with the letters CA, for example CAUB, and have an OR operator vt value (the VarType of the element and an OR operator with VT_VECTOR). The counted array structure has the following form (where name is the specific name of the counted array).
#define TYPEDEF_CA(type, name)
typedef struct tag ## name {\
ULONG cElems;\
type *pElems;\
} name
| Propvariant type | Code | Propvariant member | Value representation |
|---|---|---|---|
| VT_EMPTY | 0 | None | A property with a type indicator of VT_EMPTY has no data associated with it; that is, the size of the value is zero. |
| VT_NULL | 1 | None | This is like a pointer to NULL. |
| VT_I1 | 16 | cVal | 1-byte signed integer. |
| VT_UI1 | 17 | bVal | 1-byte unsigned integer. |
| VT_I2 | 2 | iVal | Two bytes representing a 2-byte signed integer value. |
| VT_UI2 | 18 | uiVal | 2-byte unsigned integer. |
| VT_I4 | 3 | lVal | 4-byte signed integer value. |
| VT_UI4 | 19 | ulVal | 4-byte unsigned integer. |
| VT_INT | 22 | intVal | 4-byte signed integer value (equivalent to VT_I4). |
| VT_UINT | 23 | uintVal | 4-byte unsigned integer (equivalent to VT_UI4). |
| VT_I8 | 20 | hVal | 8-byte signed integer. |
| VT_UI8 | 21 | uhVal | 8-byte unsigned integer. |
| VT_R4 | 4 | fltVal | 32-bit IEEE floating point value. |
| VT_R8 | 5 | dblVal | 64-bit IEEE floating point value. |
| VT_BOOL | 11 | boolVal (bool in earlier designs) | Boolean value, a WORD that contains 0 (FALSE) or -1 (TRUE). |
| VT_ERROR | 10 | scode | A DWORD that contains a status code. |
| VT_CY | 6 | cyVal | 8-byte two's complement integer (scaled by 10,000). This type is commonly used for currency amounts. |
| VT_DATE | 7 | date | A 64-bit floating point number representing the number of days (not seconds) since December 31, 1899. For example, January 1, 1900, is 2.0, January 2, 1900, is 3.0, and so on). This is stored in the same representation as VT_R8. |
| VT_FILETIME | 64 | filetime | 64-bit FILETIME structure as defined by Win32. It is recommended that all times be stored in Universal Coordinate Time (UTC). |
| VT_CLSID | 72 | puuid | Pointer to a class identifier (CLSID) (or other globally unique identifier (GUID)). |
| VT_CF | 71 | pclipdata | Pointer to a CLIPDATA structure, described above. |
| VT_BSTR | 8 | bstrVal | Pointer to a null-terminated Unicode string. The string is immediately preceded by a DWORD representing the byte count, but bstrVal points past this DWORD to the first character of the string. BSTRs must be allocated and freed using the Automation SysAllocString and SysFreeString calls. |
| VT_BSTR_BLOB | 0xfff | bstrblobVal | For system use only. |
| VT_BLOB | 65 | blob | DWORD count of bytes, followed by that many bytes of data. The byte count does not include the four bytes for the length of the count itself; an empty blob member would have a count of zero, followed by zero bytes. This is similar to the value VT_BSTR, but does not guarantee a null byte at the end of the data. |
| VT_BLOBOBJECT | 70 | blob | A blob member that contains a serialized object in the same representation that would appear in VT_STREAMED_OBJECT. That is, a DWORD byte count (where the byte count does not include the size of itself) which is in the format of a class identifier followed by initialization data for that class.
The only significant difference between VT_BLOB_OBJECT and VT_STREAMED_OBJECT is that the former does not have the system-level storage overhead that the latter would have, and is therefore more suitable for scenarios involving numbers of small objects. |
| VT_LPSTR | 30 | pszVal | A pointer to a null-terminated ANSI string in the system default code page. |
| VT_LPWSTR | 31 | pwszVal | A pointer to a null-terminated Unicode string in the user default locale. |
| VT_UNKNOWN | 13 | punkVal | New. |
| VT_DISPATCH | 9 | pdispVal | New. |
| VT_STREAM | 66 | pStream | A pointer to an IStream interface that represents a stream which is a sibling to the "Contents" stream. |
| VT_STREAMED_OBJECT | 68 | pStream | As in VT_STREAM, but indicates that the stream contains a serialized object, which is a CLSID followed by initialization data for the class. The stream is a sibling to the "Contents" stream that contains the property set. |
| VT_STORAGE | 67 | pStorage | A pointer to an IStorage interface, representing a storage object that is a sibling to the "Contents" stream. |
| VT_STORED_OBJECT | 69 | pStorage | As in VT_STORAGE, but indicates that the designated IStorage contains a loadable object. |
| VT_VERSIONED_STREAM | 73 | pVersionedStream | A stream with a GUID version. |
| VT_DECIMAL | 14 | decVal | A DECIMAL structure. |
| VT_VECTOR | 0x1000 | ca* | If the type indicator is combined with VT_VECTOR by using an OR operator, the value is one of the counted array values. This creates a DWORD count of elements, followed by a pointer to the specified repetitions of the value.
For example, a type indicator of VT_LPSTR|VT_VECTOR has a DWORD element count, followed by a pointer to an array of LPSTR elements. VT_VECTOR can be combined by an OR operator with the following types: VT_I1, VT_UI1, VT_I2, VT_UI2, VT_BOOL, VT_I4, VT_UI4, VT_R4, VT_R8, VT_ERROR, VT_I8, VT_UI8, VT_CY, VT_DATE, VT_FILETIME, VT_CLSID, VT_CF, VT_BSTR, VT_LPSTR, VT_LPWSTR, and VT_VARIANT. VT_VECTOR can also be combined by an OR operation with VT_BSTR_BLOB, however it is for system use only. |
| VT_ARRAY | 0x2000 | Parray | If the type indicator is combined with VT_ARRAY by an OR operator, the value is a pointer to a SAFEARRAY. VT_ARRAY can use the OR with the following data types: VT_I1, VT_UI1, VT_I2, VT_UI2, VT_I4, VT_UI4, VT_INT, VT_UINT, VT_R4, VT_R8, VT_BOOL, VT_DECIMAL, VT_ERROR, VT_CY, VT_DATE, VT_BSTR, VT_DISPATCH, VT_UNKNOWN, and VT_VARIANT. VT_ARRAY cannot use OR with VT_VECTOR. |
| VT_BYREF | 0x4000 | p* | If the type indicator is combined with VT_BYREF by an OR operator, the value is a reference. Reference types are interpreted as a reference to data, similar to the reference type in C++ (for example, "int&").
VT_BYREF can use OR with the following types: VT_I1, VT_UI1, VT_I2, VT_UI2, VT_I4, VT_UI4, VT_INT, VT_UINT, VT_R4, VT_R8, VT_BOOL, VT_DECIMAL, VT_ERROR, VT_CY, VT_DATE, VT_BSTR, VT_UNKNOWN, VT_DISPATCH, VT_ARRAY, and VT_VARIANT. |
| VT_VARIANT | 12 | capropvar | A DWORD type indicator followed by the corresponding value. VT_VARIANT can be used only with VT_VECTOR or VT_BYREF. |
| VT_TYPEMASK | 0xFFF | Used as a mask for VT_VECTOR and other modifiers to extract the raw VT value. |
Clipboard format identifiers, stored with the tag VT_CF, use one of five representations, identified in the ulClipFmt member of the CLIPDATA structure using the pClipData pointer to the particular data type.
| ulClipFmt value | pClipData value |
|---|---|
| -1L | A DWORD that contains a built-in Windows clipboard format value. |
| -2L | A DWORD that contains a Macintosh clipboard format value. |
| -3L | A GUID that contains a format identifier (FMTID). This is rarely used. |
| any positive value | A null-terminated string that contains a Windows clipboard format name, one suitable for passing to the RegisterClipboardFormat function. This function registers a new clipboard format. If a registered format with the specified name already exists, a new format is not registered and the return value identifies the existing format. This enables more than one application to copy and paste data using the same registered clipboard format. The format name comparison is case insensitive and is identified by values in the range from 0xC000 through 0xFFFF. The code page used for characters in the string is according to the code-page indicator. The "positive value" here is the string length, including the null byte at the end. When register clipboard formats are placed on or retrieved from the clipboard, they must be in the form of an HGLOBAL data-type value, which provides the handle to the object. |
| 0L | No data (rarely used). |
If the value of the ulClipFmt member is -1, the data is in the form of a built-in Windows format. In this case, the first DWORD of the buffer pointed to by pClipData is the clipboard format identifier, for example CF_METAFILEPICT. In the case of CF_METAFILEPCT, what follows is a variation on the METAFILEPICT structure (it uses WORD, rather than DWORD data types). That is, this data is in the following form:
struct PACKEDMETA
{
WORD mm;
WORD xExt;
WORD yExt
WORD reserved;
};
After the METAFILEPICT structure is the metafile data, suitable to be passed to the SetMetaFileBitsEx function. This function creates a memory-based, Windows-format metafile from the supplied data. This function is provided for compatibility with 16-bit versions of Windows. Win32-based applications should use the SetEnhMetaFileBits function. This function retrieves the contents of the specified enhanced-format metafile and copies them into a buffer. If the function succeeds and the buffer pointer is NULL, the return value is the size of the enhanced metafile in bytes. If the function succeeds and the buffer pointer is a valid pointer, the return value is the number of bytes copied to the buffer. If the function fails, the return value is zero.
When register clipboard formats are placed on or retrieved from the clipboard, they must be in the form of an HGLOBAL value.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps | UWP apps] |
| Minimum supported server | Windows 2000 Server [desktop apps | UWP apps] |
| Header | propidlbase.h (include Propidl.h) |