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2005.03.17 03:10 "Re: Need to write CCITT T.6 encoded TIFF filedatadirectlytomemory buffer", by Joris Van Damme
Roger,
> After using TIFFClientOpen() and setting up special handler functions, will
> TIFFClose() work appropriately for the tiff so opened?
TIFFClose will call the 'platform/medium dependent' close procedure, a pointer
to which is also a parameter of the TIFFClientOpen functions. This
platform/medium dependent close procedure of your own implementation can take
care of specific closing and cleaning up. This explains the following
implementations of such platform/medium dependent close procedures in
LibTiffDelphi.pas:
for file, just use the windows CloseHandle function on the file handle, as this
is the proper equivalent of the TIFFOpen action implementation
function TIFFFileCloseProc(Fd: Cardinal): Integer; cdecl;
begin
if CloseHandle(Fd)=True then
Result:=0
else
Result:=-1;
end;
for stream, there is no opening as such, and there is also no closing
equivalent:
function TIFFStreamCloseProc(Fd: Cardinal): Integer; cdecl;
begin
Result:=0;
end;
The most common mistake when using TStream, is forgetting to reset the 'file
pointer' back to 0. This is needed when having written, and next eg reading
back. It may be the cause of your question. You can reset the 'file pointer'
calling its Seek method with parameters (0,soFromBeginning).
Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
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