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4/8/2010

This function frees the specified storage medium.

Syntax 

void ReleaseStgMedium( 
  STGMEDIUM* 
pmedium
);

Parameters

pmedium

[in] Pointer to the storage medium that is to be freed.

Return Value

None.

Remarks

The ReleaseStgMediumfunction calls the appropriate method or function to release the specified storage medium.

Use this function during data transfer operations where storage medium structures are parameters.

In addition to identifying the type of storage medium, this structure specifies the appropriate Releasemethod for releasing the storage medium when it is no longer needed.

It is common to pass a STGMEDIUMfrom one body of code to another, in which the one called can allocate a medium and return it to the caller.

ReleaseStgMediumpermits flexibility in whether the receiving body of code owns the medium, or whether the original provider of the medium still owns it; in which case the receiving code must inform the provider that it can free the medium.

When the original provider of the medium is responsible for freeing the medium, the provider calls ReleaseStgMedium, specifying the medium and the appropriate IUnknownpointer as the punkForReleasestructure member.

Depending on the type of storage medium being freed, one of the following actions is taken, followed by a call to the Releasemethod on the specified IUnknownpointer.

Medium ReleaseStgMedium action

TYMED_HGLOBAL

None.

TYMED_GDI

None.

TYMED_ENHMF

None.

TYMED_MFPICT

None.

TYMED_FILE

Frees the file name string using standard memory management mechanisms.

TYMED_ISTREAM

Calls IStream::Release.

TYMED_ISTORAGE

Calls IStorage::Release.

The provider indicates that the receiver of the medium is responsible for freeing the medium by specifying NULL for the punkForReleasestructure member.

Then the receiver calls ReleaseStgMedium, which makes a call as described in the following table, depending on the type of storage medium being freed.

Medium ReleaseStgMedium action

TYMED_HGLOBAL

Calls the LocalFreefunction on the handle.

TYMED_GDI

Calls the Microsoft® Win32® DeleteObjectfunction on the handle.

TYMED_ENHMF

Deletes the enhanced metafile.

TYMED_FILE

Frees the disk file by deleting it.

Frees the file name string by using the standard memory management paradigm.

TYMED_ISTREAM

Calls IStream::Release.

TYMED_ISTORAGE

Calls IStorage::Release.

In either case, after the call to ReleaseStgMedium, the specified storage medium is invalid and can no longer be used.

To determine whether the platform supports this function, see Determining Supported COM APIs.

Requirements

Header ole2.h
Library ole32.lib
Windows Embedded CE Windows CE 2.10 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also