IPegasusFileFilter::NextConvertFile

This method is called by the H/PC Explorer when the user selects a conversion type from the H/PC Explorer conversion selection dialog box.

At a Glance

Header file:	Replfilt.h
Windows CE versions:	1.0 and later

Syntax

STDMETHODIMP IPegasusFileFilter::NextConvertFile( int nConversion, PFF_CONVERTINFO *pci, PFF_SOURCEFILE *psf, PFF_DESTINATIONFILE *pdf, volatile BOOL *pbCancel, PR_ERROR *perr );

Parameters

nConversion

Counter for converting a single source file into multiple destination files. This parameter is zero the first time NextConvertFile is called and is incremented for each successive call. A simple filter should return HRESULT_FROM_WIN32(ERROR_NO_MORE_ITEMS) if this parameter is not zero.

pci

Pointer to a PFF_CONVERTINFO structure that contains a pointer to an IPegasusFileFilterSite object. A file filter uses this interface to create an IStream or IStorage object to read the contents of the source file or to write to the destination file. The type of interface object to create is determined by the nHowToOpen parameter in the IPegasusFileFilterSite::OpenSourceFile and IPegasusFileFilterSite::OpenDestinationFile methods. Any files opened in this way should be closed using the corresponding IPegasusFileFilterSite::CloseSourceFile or IPegasusFileFilterSite::CloseDestinationFile method.

psf

Pointer to a PFF_SOURCEFILE structure that contains information about the source file.

pdf

Pointer to a PFF_DESTINATIONFILE structure that contains information about the destination file.

pbCancel

Pointer to a Boolean value that is set to TRUE if the user cancels the file conversion before it is completed, or to FALSE otherwise. Because this variable is updated asynchronously by another thread, its contents can change at any time. A file filter must check this variable regularly during the conversion process, and return ERROR_CANCELLED (after cleaning up) if it is ever set to TRUE.

perr

Pointer to a filter-defined error value that can be passed by the H/PC Explorer application to the IPegasusFileFilter::FormatMessage method. This error value is ignored unless the return value from NextConvertFile is E_FAIL.

Return Values

One of the values described in the following table is returned.

NOERROR

The subconversion was successful; proceed to the next subconversion.

HRESULT_FROM_WIN32 (ERROR_CANCELLED)

The user canceled the conversion.

HRESULT_FROM_WIN32 (ERROR_NO_MORE_ITEMS)

The conversion, or last subconversion, was successful. End calls to IPegasusFileFilter::NextConvertFile.

E_FAIL

The perr parameter contained an error value that should be passed to IPegasusFileFilter::FormatMessage.

Remarks

H/PC Explorer calls the IPegasusFileFilter::NextConvertFile method repeatedly, incrementing the nConversion parameter, until the return value is ERROR_NO_MORE_ITEMS. A simple filter should return NOERROR the first time this method is called, and thereafter return HRESULT_FROM_WIN32(ERROR_NO_MORE_ITEMS). Alternatively, a file filter can return E_FAIL and specify a filter-defined error code in the variable pointed to by perr.

As a file conversion progresses, a file filter should periodically call IPegasusFileFilterSite::ReportProgress to report its progress. H/PC Explorer uses the progress information to update a progress bar that shows the user how much of the conversion is complete.

If any important data is intentionally discarded by a file filter during the conversion process, the filter should call IPegasusFileFilterSite::ReportLoss to report the loss. When calling this ReportLoss, the filter specifies a message that explains the data loss, and H/PC Explorer formats and displays the message in a message box when the file conversion has completed. For more information, see Transferring Files.