Visual Basic (6.0 and below) Sample: Acquire and save to BMP file

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The following Visual Basic (6.0 and below) function is all that is required to do the following:

 

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Check if TWAIN is installed.

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Initialize the DTWAIN Dynamic Link Library.

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Select a Source

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Acquire a page using the Native transfer mode

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Save page to a BMP file called "test.bmp"

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Shut down any open TWAIN Source's and DTWAIN itself

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Private Sub ExampleFunction( )

 

Dim SelectedSource As Long

Dim RetVal As Long

Dim ErrStatus As Long

 

Rem Check for Twain

if DTWAIN_IsTwainAvailable Then

     Rem Initialize DTWAIN

    DTWAIN_SysInitialize

 

     Rem open a TWAIN Source

     SelectedSource = DTWAIN_SelectSource

      if SelectedSource Then

 

            Rem Acquire to a BMP file

            RetVal = DTWAIN_AcquireFile(SelectedSource,  "test.bmp", DTWAIN_BMP, _

                                                                    DTWAIN_USENATIVE + DTWAIN_USENAME,  _

                                                                    DTWAIN_PT_DEFAULT, 1, 1, 1, ErrStatus)

      End If

      Rem Shut down DTWAIN

      DTWAIN_SysDestroy            

End If

EndSub

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Add the DTWAIN32.BAS interface to the Visual Basic project to define the DTWAIN functions, and that is all that's needed to compile the function correctly.  Note that this is function shows complete usage of DTWAIN from start to finish.  There are no other "hidden" DTWAIN calls or setup to do.  Of course, your VB application would more than likely be more advanced, however this example illustrates what can be done with just a few lines of code.

 

To acquire to the other file types other than BMP, the parameter that specifies DTWAIN_BMP can be any of the other file types such as DTWAIN_GIF, DTWAIN_JPEG, etc..  Therefore just 5 calls can save a file to any of many file types by just changing the third parameter to DTWAIN_AcquireFile

 

We will boldly challenge you to try to implement TWAIN image retrieval without DTWAIN, especially if you use Visual Basic.  You will realize that you will save weeks and possibly months of programming time using DTWAIN than if you tried to implement this yourself.