L_TwainAcquire

#include "lttwn.h"

L_LTTWN_API L_INT L_TwainAcquire (hSession, pBitmap, uStructSize, pfnCallBack, uFlags, lpszTemplateFile, pUserData)

Acquires one or more images from a TWAIN source.

Returns

Comments

When acquiring multiple pages, the LTWAINBITMAPCALLBACK callback function receives the scanned images through the pBitmap parameter. The user can then process these images as desired within the callback function.

When acquiring a single page, pass NULL for the pfnCallBack parameter. The pBitmap is updated with the single scanned image.

The number of pages to acquire can be determined by getting the TWAIN source's capabilities. To change the number of pages to acquire, set the appropriate capability to the desired number.

To cancel the acquire operation call the L_TwainCancelAcquire from within the LTWAINBITMAPCALLBACK callback function.

To stop acquiring images only from the feeder of the TWAIN source, call the L_TwainStopFeeder function from within the LTWAINBITMAPCALLBACK callback function.

When scanning multi pages or multi areas with memory transfer mode, you may use LTWAIN_MEMORY_CHECK_IMAGEINFO flag to let the function check the image information for each page or area before start pending the image data to application. Some TWAIN drivers do not support image information checking, so passing this flag has no effect on the function.

The usage of the flag does not follow the TWAIN specification, but is included as work around for TWAIN drivers that scan multiple pages with different image dimensions. The usage of this flag should be limited only to these special and unusual cases.

In order to use LTWAIN_IMAGESIZE_UNDEFINED flag, you should set ICAP_XFERMECH capability to TWSX_MEMORY and then set ICAP_UNDEFINEDIMAGESIZE capability to TRUE, before calling this function, otherwise, it will return an error.

The LTWAIN_KEEPOPEN flag works only in the following cases:

Required DLLs and Libraries

See Also

Example

static L_INT EXT_CALLBACK BmpCB(HTWAINSESSION hSession,
                                pBITMAPHANDLE pBitmap,
                                L_VOID     * pUserData)
{
   UNREFERENCED_PARAMETER(hSession);
   UNREFERENCED_PARAMETER(pBitmap);
   UNREFERENCED_PARAMETER(pUserData);
   // You can do here any processing to the bitmap
   return SUCCESS;
}

 L_INT TwainAcquireExample(pBITMAPHANDLE pBitmap,HTWAINSESSION g_hSession) 
{
   L_INT nRet;
   TW_CAPABILITY twCap;

   // Show the Twain Select Source UI
   nRet = L_TwainSelectSource(g_hSession, NULL);
   if (nRet != SUCCESS) 
   {
      MessageBox (NULL, TEXT("Error occurred while selecting the source."),TEXT( "ERROR"), MB_OK);
      return nRet;
   }

   nRet = L_TwainStartCapsNeg(g_hSession);
   if(nRet != SUCCESS)
      return nRet;

   twCap.Cap = ICAP_XFERMECH;
   twCap.ConType = TWON_ONEVALUE;

   nRet = L_TwainCreateNumericContainerOneValue(&twCap, TWAINNUMERICTYPE_TW_UINT16, TWSX_NATIVE);
   if(nRet != SUCCESS)
      return nRet;

   nRet = L_TwainSetCapability(g_hSession, &twCap, LTWAIN_CAPABILITY_SET);
   if(nRet != SUCCESS)
      return nRet;
   nRet = L_TwainFreeContainer(&twCap);
   if(nRet != SUCCESS)
      return nRet;
   nRet = L_TwainEndCapsNeg(g_hSession);
   if(nRet != SUCCESS)
      return nRet;

   nRet = L_TwainAcquire(g_hSession, pBitmap, sizeof(BITMAPHANDLE), BmpCB, LTWAIN_SHOW_USER_INTERFACE, NULL, NULL);
   if (nRet == SUCCESS)
      MessageBox(NULL, TEXT("The image acquisition process completed."), TEXT("Notice"), MB_OK);
   else
   {
      MessageBox(NULL, TEXT(" The image acquisition process failed!"), TEXT("Error"), MB_OK);
      return nRet;
   }
   return SUCCESS;
}