Re: preflighting a file
Re: preflighting a file
- Subject: Re: preflighting a file
- From: Andy Wylie <email@hidden>
- Date: Tue, 19 Feb 2002 16:21:22 +1300
on 19/2/02 1:54 PM, Shane Stanley at email@hidden wrote:
>
On 19/2/02 10:32 AM +1000, Pat Cannon, email@hidden, wrote:
>
>
> Try this (you'll probably have to fix a couple line breaks):
<snip> script
>
> You can probably speed it up by making chunksize bigger -- this took a
>
> minute and a half to read through a 4.8MB file on my G4.
>
>
But you're not allowing for the possibility of "CalGray" falling across the
>
boundary of two chunks. To be safe, you need to do something like store the
>
last paragraph of each chunk, then concatenate the next chunk to it each
>
time.
>
>
You would also speed things up a fair bit if you used "open for
>
access"/"close access"; as it stands, opening and closing being done
>
(automatically) each time you read. As a bonus, you would then no longer
>
have to keep track of where you were in the file -- you would just "read for
>
1024" each time.
But this still errors when it hits eof, my crude fix (with no good reason
not to use offset(yet:))...
-------------
on open theFile
set |eof| to get eof of file theFile
open for access alias theFile
try
set startChunk to 1
repeat
set endChunk to startChunk + 4024
if endChunk > |eof| then set endChunk to |eof|--no error -39
set theText to read theFile from startChunk to endChunk
if startChunk > 1 then
set startChunk to endChunk - 10
else
set startChunk to endChunk
end if
if (offset of "CalGray" in theText) > 0 then
display dialog "CalGray @ offset" & (offset of "CalGray" in
theText)
exit repeat
end if
end repeat
close access theFile
on error m number n
error {n, m}
close access theFile
end try
end open
_____________________________ Andy
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