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Date Posted: 17:59:58 02/22/01 Thu
Author: Michel
Subject: Re: Keeping TWAIN interface loaded
In reply to: Michael Mount 's message, "Re: Keeping TWAIN interface loaded" on 09:42:08 02/22/01 Thu


Hi Mike,

Could you email me your modified EnScan.Pas. I'll check it out from there and ensure it does not change the existing functionality.

Best regards,

Michel

>Hi Michel,
>
>I tried as you suggested and seem to have cut the per
>scan time in half. I wanted to run this by you to
>make sure I didn't do anything stupid in the process
>since I'm not 100% certain of what everything does.
>
>The BeginAcquire procedure was everything in Acquire
>up to and including ApplyOptions. I wrapped that all
>in a try..except block with the except portion calling
>EndAcquire.
>
>The other two procedures follow:
>
>procedure TScanner.AcquireWithSourceOpen( const
>AcquireEvent : TAcquireEvent;
> const
>CallBackData : LongInt );
>var
> TwainUI : TW_USERINTERFACE;
>begin
> if FTwainData.SourceID.ID = 0 then BeginAcquire;
> try
> try
> FillChar(TwainUI, SizeOf(TwainUI), 0);
> TwainUI.ShowUI := FTwainData.ShowUI;
> TwainUI.hParent := FTwainData.ParentHandle;
>
> if not CallTriplet( @FTwainData.SourceId,
>@FTwainData.AppId,
> DG_CONTROL,
>DAT_USERINTERFACE,
> MSG_ENABLEDS,
>@TwainUI, nil, FTwainData.DsmEntry) then
> raise ETwainError.Create('Unable to
>enable twain source.');
>
> ProcessImages( AcquireEvent,
> @FTwainData.SourceId,
>@FTwainData.AppId,
> FTwainData.DsmEntry,
>CallBackData);
>
> finally
> CallTriplet( @FTwainData.SourceId,
>@FTwainData.AppId,
> DG_CONTROL, DAT_USERINTERFACE,
> MSG_DISABLEDS, @TwainUI, nil,
>FTwainData.DsmEntry);
> end;
> except
> EndAcquire;
> end;
>end;
>
>procedure TScanner.EndAcquire;
>var
> TwainUI: TW_USERINTERFACE;
>begin
> try
> FillChar(TwainUI, SizeOf(TwainUI), 0);
> TwainUI.ShowUI := FTwainData.ShowUI;
> TwainUI.hParent := FTwainData.ParentHandle;
>
> CallTriplet(
> @FTwainData.SourceId, @FTwainData.AppId,
> DG_CONTROL, DAT_USERINTERFACE,
>MSG_DISABLEDS, @TwainUI,
> nil, FTwainData.DsmEntry);
>
> finally
> if FTwainData.SourceId.Id <> 0 then
> begin
> if not CallTriplet( nil,
>@FTwainData.AppId, DG_CONTROL, DAT_IDENTITY,
>MSG_CLOSEDS,
> @FTwainData.SourceId,
>nil, FTwainData.DsmEntry) then
> raise ETwainError.Create('Unable to
>close TWAIN data source');
>
> FillChar(FTwainData.SourceId,
>SizeOf(FTwainData.SourceId), 0);
> end;
> end;
>end;
>
>I think that this closes the TwainUI after each call
>to AcquireWithSourceOpen but does not actually unload
>the drivers so the reentry time is significantly
>reduced. Does this look right to you? I removed the
>EnableWindow call because I didn't want to track the
>previous value across methods. Thanks for all your
>help.
>
>- Mike
>
>>Hi Mike,
><SNIP>
>>I'll add this to the todo list. Let me know if you try
>>this out.
>>
>>Best regards,
>>
>>Michel

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