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Date Posted: 10:57:25 04/08/00 Sat
Author: Michel
Subject: Re: Scanning in CBuilder
In reply to: Cameron 's message, "Scanning in CBuilder" on 20:51:49 04/06/00 Thu


Hi Cameron,

I have created a simple BCB5 example and I think your problem is that you OnAcquire function is not a member function. The OnAquire function must be part of your main form (or another TObject descendant). For example, here is the class definition of the main form in my project:

class TMainForm : public TForm
{
__published: // IDE-managed Components
TImageScrollBox *ImageScrollBox;
TPanel *TopPanel;
TButton *ScanBtn;
TButton *SelectScannerBtn;
void __fastcall FormCreate(TObject *Sender);
void __fastcall FormDestroy(TObject *Sender);
void __fastcall ScanBtnClick(TObject *Sender);
void __fastcall SelectScannerBtnClick(TObject *Sender);
private: // User declarations
TScanner *FScanner;

void __fastcall ImageAcquired(
const unsigned DibHandle,
const Word XDpi,
const Word YDpi,
const int CallBackData);

public: // User declarations
__fastcall TMainForm(TComponent* Owner);
};

Then in the cpp file I have these two methods to handle the scanning:

void __fastcall TMainForm::ScanBtnClick(TObject *Sender)
{
FScanner->Acquire( ImageAcquired, 0 );
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::ImageAcquired(
const unsigned DibHandle,
const Word XDpi,
const Word YDpi,
const int CallBackData)
{
ImageScrollBox->Graphic->AssignFromDIBHandle(DibHandle);
ImageScrollBox->Redraw(True);
}

You'll may download the complete example project in,

<a rel=nofollow target=_blank href="http://www.intervalsoftware.com/files/scandemoCB5.zip">http://www.intervalsoftware.com/files/scandemoCB5.zip</a>

Best regards,

Michel

> I'm using a registered copy to create a program the
> activates a scanner and saves the output to the file.
> If I use the example Delphi code, everything is fine.
> But since I am more comforatble in C++, I've converted
> the program to C and have just one annoying problem.
> If I create an OnAcquire function to use in
> TScanner::Acquire, I get an error message
> E2031 Cannot cast from 'void (_fastcall *)(const
> unsigned int,const unsigned short,const unsigned
> short,const int)' to 'void (_fastcall * (_closure
> )(const unsigned int,const unsigned short,const
> unsigned short,const int))(const unsigned int,const
> unsigned short,const unsigned short,const int)'.
> How should the OnAcuire function be defined and
> call in C++ for the TScanner component to work.

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