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Date Posted: 11:29:28 05/02/03 Fri
Author: Don
Subject: Re: Testing Envision Image Library C Builder
In reply to: Michel 's message, "Re: Testing Envision Image Library C Builder" on 18:33:39 05/01/03 Thu

Hi,

So are you saying that I can create and use my own method of passing parameters and defining the OnAcquire event?
Also can I control other Scanner parameters such as contrast, brightness, landscape, etc.. ?

Thanks,
Don
>
>Hi Don,
>
>I do not have a CBuilder demo complete like the
>example program. Usually the port from C++ to Object
>Pascal is quite straight forward, replacing
>TObject.Create with new TObject() from Free with
>Delete. Remember all VCL objects must be created
>explicitely in CBuiler.
>
>I think the problem you are having is that your type
>TpScanInfo is not pointer type, but an "alias" for the
>structure. The convention I use is that a structure
>type has the format TStructure, and the typedef for a
>pointer to the structure is TpStructure. I know there
>are various ways to identify the name of a struct in C
>(whether you use straight C or C++ extensions), but I
>don't recall the exact differences.
>
>The cast you have is trying to cast from an integer
>(CallBackData) to a user defined structure, to the
>compiler complains. This will probably work,
>
>pScanInfo = TpScanInfo*(CallBackData);
>
>The idea is that a pointer is 4 bytes just like an
>integer.
>
>Note that a proper value (ie, the address of a
>TScanInfo structure) must be passed to
>TScanner->Acquire(), to use this call back data
>mechanism.
>
>You can avoid the call back data mechanism, by simply
>holding the information globally on the form.
>
>Best regards,
>
>Michel
>>I am testing your Library with C++ Builder 5 Pro. I am
>>trying to create a C++ Builder App to test with based
>>on your Delphi/Pas Demo. Do you have the same code in
>>C++?
>>Here is a sample of my code and the current error I am
>>getting.
>>
>>In Header file:
>>
>>private: // User declarations
>> void __fastcall OnAcquire( const THandle
>>DibHandle, const unsigned short XDpi,
>> const unsigned
>>short YDpi, const int CallBackData);
>> typedef struct TpScanInfo
>> {
>> bool MultiPage;
>> const TTiffGraphic* Graphic;
>> TFileStream *ScanStream;
>> long int ImageCount;
>> } TScanInfo;
>>
>>In CPP Unit:
>>
>>void __fastcall TForm1::OnAcquire( const THandle
>>DibHandle, const unsigned short XDpi,
>> const unsigned short YDpi,
>>const int CallBackData)
>>{
>>
>>TScanInfo *pScanInfo = new TScanInfo;
>>pScanInfo = TpScanInfo(CallBackData);
>>
>>Here is where the error is generated:
>>
>>[C++ Error] MainUnit.cpp(77): E2031 Cannot cast from
>>'const int' to 'TForm1::TpScanInfo'
>>
>>Thanks,
>>
>>Don

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