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Date Posted: 07:15:46 04/11/00 Tue
Author: Michel
Subject: Re: Scanning several Images
In reply to: Guy Pigerre 's message, "Re: Scanning several Images" on 19:36:46 04/10/00 Mon


Hi Guy,

I'm really not sure what the problem is. I know another user is have the same problem with the film scan driver as posted on borland.public.delphi.graphics on April 7:

<<

Subject: Re: Scanner TWAIN how to control?
Date: Fri, 7 Apr 2000 01:39:09 +0200
From: "Michel TORREILLES" <amictor@evc.net>
Organization: Another Netscape Collabra Server User
Newsgroups: borland.public.delphi.graphics
References: 1 , 2

Hi Charles

I read that you are using MultiTwain. I would like to use it to do multiples scanning with the EPSON Filmscan 200.
I have try the demo but the scanning stops after the first scan. Can you send me an example of code giving the ability of multiple scan. Using "TWAIN_AcquireNative" or "TWAIN_AcquireToFilename" using "TWAIN_RegisterCallback" how ?
>>

Unfortunately, there is not any postive response in the newsgroup.

Here is the code snippet which determines if there are more images in a twain transfer:

var
PendingXFers : TW_PENDINGXFERS;
TwainResult : TW_UINT16;

begin

{ acknowledge end of transfer }
CallTriplet( pSourceId, pAppId,
DG_CONTROL, DAT_PENDINGXFERS,
MSG_ENDXFER, @PendingXfers,
@TwainResult, dsmEntry);

if TwainResult = TWRC_SUCCESS then
{ PendingTransfers may be -1, so check <> 0 }
PendingTransfers := (PendingXfers.Count <> 0)
else
begin
PendingTransfers := False;

{ if Result is False due to an error the transition
to state 5 is not automatic. }
AbortTransfer(pSourceId, pAppId, DsmEntry);
end;

end;

PendingXfers.Count is probably returning 0 with this twain driver, or the TwainResult is not equal to TWRC_SUCCESS.

I'll try to download the driver somewhere and hopefully it will allow transferring images without the device.

Best regards,

Michel

> The problem persists when the demo is run outside the
> IDE and with Delphi not running.
>
> Epson FilmScan is a film scanner. It scans a film
> from a non-digital camera. The program that drives it
> is called "Epson Twain32".
>
> You wrote:
> > When an image is scanned with Twain, a value
> > indicating there are more images is returned to the
> > application. This is how Envision works.
>
> I cannot see any variable relating to the number of
> images in the OnAcquire event.
>
> Why is Demo closing the TWain driver program after one
> image has been scanned?
>
>
> Thanks for your answer.

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