IEmptyVolumeCache::GetSpaceUsed method (emptyvc.h)
Requests the amount of disk space that the disk cleanup handler can free.
HRESULT GetSpaceUsed( [out] DWORDLONG *pdwlSpaceUsed, [in] IEmptyVolumeCacheCallBack *picb );
The amount of disk space, in bytes, that the handler can free. This value will be displayed in the disk cleanup manager's list, to the right of the handler's check box. To indicate that you do not know how much disk space can be freed, set this parameter to -1, and "???MB" will be displayed. If you set the EVCF_DONTSHOWIFZERO flag when Initialize was called, setting pdwSpaceUsed to zero will notify the disk cleanup manager to omit the handler from its list.
This method can return one of these values.
||An error occurred when the handler tried to calculate the amount of disk space that could be freed.|
||The scan operation was ended prematurely. This value is usually returned when a call to ScanProgress returns E_ABORT. This return value indicates that the user canceled the operation by clicking the disk cleanup manager's Cancel button.|
When this method is called by the disk cleanup manager, the handler should start scanning its files to determine which of them can be deleted, and how much disk space will be freed. Handlers should call IEmptyVolumeCache::ScanProgress periodically to keep the user informed of the progress of the scan, especially if it will take a long time. Calling this method frequently also allows the handler to determine whether the user has canceled the operation. If ScanProgress returns E_ABORT, the user has canceled the scan. The handler should immediately stop scanning and return E_ABORT.
You should only set the pdwSpaceUsed parameter to -1 as a last resort. The handler is of limited value to a user if they don't know how much space will be freed.
|Minimum supported client||Windows 2000 Professional, Windows XP [desktop apps only]|
|Minimum supported server||Windows Server 2003 [desktop apps only]|
|DLL||Shell32.dll (version 5.0 or later)|