AssocGetPerceivedType function (shlwapi.h)

Retrieves a file's perceived type based on its extension.

Syntax

LWSTDAPI AssocGetPerceivedType(
  [in]            PCWSTR        pszExt,
  [out]           PERCEIVED     *ptype,
  [out]           PERCEIVEDFLAG *pflag,
  [out, optional] PWSTR         *ppszType
);

Parameters

[in] pszExt

Type: PCWSTR

A pointer to a buffer that contains the file's extension. This should include the leading period, for example ".txt".

[out] ptype

Type: PERCEIVED*

A pointer to a PERCEIVED value that indicates the perceived type.

[out] pflag

Type: PERCEIVEDFLAG*

A pointer to a value that indicates the source of the perceived type information. One or more of the following values.

PERCEIVEDFLAG_UNDEFINED (0x0000)

No perceived type was found (PERCEIVED_TYPE_UNSPECIFIED).

PERCEIVEDFLAG_SOFTCODED (0x0001)

The perceived type was determined through an association in the registry.

PERCEIVEDFLAG_HARDCODED (0x0002)

The perceived type is inherently known to Windows.

PERCEIVEDFLAG_NATIVESUPPORT (0x0004)

The perceived type was determined through a codec provided with Windows.

PERCEIVEDFLAG_GDIPLUS (0x0010)

The perceived type is supported by the GDI+ library.

PERCEIVEDFLAG_WMSDK (0x0020)

The perceived type is supported by the Windows Media SDK.

PERCEIVEDFLAG_ZIPFOLDER (0x0040)

The perceived type is supported by Windows compressed folders.

[out, optional] ppszType

Type: PWSTR*

If the function returns a success code, this contains the address of a pointer to a buffer that receives the perceived type string, for instance "text" or "video". This value can be NULL.

Return value

Type: HRESULT

If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

This function first compares the extension against a hard-coded set of extensions known to Windows. If that search fails to reveal a match, the registered associations under HKEY_CLASSES_ROOT are searched for a key that matches the extension and contains a PerceivedType value. If that value is found, the extension set is again searched for a match. If again no match is found, the perceived type is determined to be PERCEIVED_TYPE_CUSTOM. If either a key that matches the extension or a PerceivedType value is not found, the perceived type is reported as PERCEIVED_TYPE_UNSPECIFIED.

Requirements