Python Sample: Acquire and save to BMP file

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The following Python script is all that is required to do the following:

 

•

Initialize the DTWAIN Dynamic Link Library.

•

Select a Source

•

Display the capabilities of the source

•

Acquire a page using the Native transfer mode

•

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

•

Shut down any open TWAIN Source's and DTWAIN itself

 

from ctypes import *

import dtwain

import struct

import ctypes as ct


def test_dtwain():

    # Load the DTWAIN library (make sure "dtwain32u.dll" or "dtwain64u.dll" is accessible)

    # You can use a full pathname here also, to ensure python finds the dll

    

    # Check for the python environment, and load the Unicode 64-bit or 32-bit DLL

    if struct.calcsize("P") * 8 == 64:

        dtwain_dll = dtwain.load_dtwaindll("dtwain64u.dll")

    else:

        dtwain_dll = dtwain.load_dtwaindll("dtwain32u.dll")


    # Initialize DTWAIN

    dtwain_dll.DTWAIN_SysInitialize()

    

    # Select a TWAIN source

    TwainSource = dtwain_dll.DTWAIN_SelectSource()

    if TwainSource:


        # Display the product name of the Source

        # Create a char buffer to allow calling DTWAIN_GetSourceProductNameA

        #

        # If instead you wanted to call DTWAIN_GetSourceProductName, you will need a Unicode

        # buffer, i.e. ct.create_unicode_buffer(100), since python loaded the Unicode version

        # of the DTWAIN DLL

        #

        mystrbuf = ct.create_string_buffer(100)

        dtwain_dll.DTWAIN_GetSourceProductNameA(TwainSource, mystrbuf, len(mystrbuf))

        print (mystrbuf.value)

        

        # Example usage of DTWAIN_ARRAY:

        # Get the device capabilities supported by the device

        #

        # Note: The DTWAIN_ARRAY, DTWAIN_SOURCE, DTWAIN_FRAME, and DTWAIN_RANGE are actually void pointers

        # so you have to declare them as such if a DTWAIN function requires a parameter to be of this type.

        dtwain_array = ct.c_void_p(0)


        # Note that the second parameter is the address a DTWAIN_ARRAY, i.e. a LPDTWAIN_ARRAY

        dtwain_dll.DTWAIN_EnumSupportedCaps(TwainSource, ct.byref(dtwain_array))


        # Get the number of items in the array

        arrcount = dtwain_dll.DTWAIN_ArrayGetCount(dtwain_array)

        print(f"There are {arrcount} device capabilities")


        #print each capability

        for i in range(arrcount):

            long_val = ct.c_long(0)

            dtwain_dll.DTWAIN_ArrayGetAtLong(dtwain_array, i, ct.byref(long_val))

            dtwain_dll.DTWAIN_GetNameFromCapA(long_val, mystrbuf, len(mystrbuf))

            print(f"Capability {i+1}: {mystrbuf.value}  Value: {long_val.value}")


        # Destroy the array when done

        dtwain_dll.DTWAIN_ArrayDestroy(dtwain_array)


        # Now Acquire to a BMP file

        dtwain_dll.DTWAIN_AcquireFile(TwainSource, "TEST.BMP", dtwain.DTWAIN_BMP, dtwain.DTWAIN_USELONGNAME,

                                       dtwain.DTWAIN_PT_DEFAULT, 1, 1, 1, None)

    # Close down DTWAIN                                      

    dtwain_dll.DTWAIN_SysDestroy()


if __name__ == '__main__':

    test_dtwain()

Note that the cTypes facility of Python is used to interface to the DTWAIN functions.  The DLL files dtwain32u.dll and/or dtwain64u.dll needs to be available in the load_dtwaindll function call. 

 

Also, the import dtwain imports the constants defined by the DTWAIN library. The dtwain.py module contains the constant and function definitions, and should be located in your Python's path for imports (or in the same directory as your Python scripts).