ICeFileFilter::NextConvertFile

This method is called by Windows CE Services when the user selects a conversion type from the Windows CE Services conversion selection dialog box.

At a Glance

Header file:	Replfilt.h
Windows CE versions:	2.0 and later

Syntax

STDMETHODIMP ICeFileFilter::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 CFF_CONVERTINFO structure that contains a pointer to an ICeFileFilterSite 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 ICeFileFilterSite::OpenSourceFile and ICeFileFilterSite::OpenDestinationFile methods. Any files opened in this way should be closed using the corresponding ICeFileFilterSite::CloseSourceFile or ICeFileFilterSite::CloseDestinationFile method.

psf

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

pdf

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

pbCancel

Pointer to a Boolean that is set to TRUE if the user cancels the file conversion before it is completed, or set 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 Windows CE Services application to the ICeFileFilter::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.

Value	Description
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 ICeFileFilter::NextConvertFile.
E_FAIL	The perr parameter contained an error value that should be passed to ICeFileFilter::FormatMessage.

Remarks

The Explorer window for the mobile device calls the ICeFileFilter::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 value in the variable pointed to by perr.

As a file conversion progresses, a file filter should periodically call ICeFileFilterSite::ReportProgress to report its progress. Windows CE Services 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 ICeFileFilterSite::ReportLoss to report the loss. When calling this ReportLoss, the filter specifies a message that explains the data loss, and Windows CE Services formats and displays the message in a message box when the file conversion has completed. For more information, see Transferring Files.