LTwain::Acquire

#include "ltwrappr.h"

virtual L_INT LTwain::Acquire (pBitmap, uStructSize, uFlags, lpszTemplateFile)

virtual L_INT LTwain::Acquire (Bitmap, uStructSize, uFlags, lpszTemplateFile)

Acquires one or more images from a TWAIN source.

Returns

Comments

When acquiring multiple pages, the LTwain::BitmapCallBack 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 LTwain::CancelAcquire within the LTwain::BitmapCallBack function when it is fired.

To stop acquire images only from the feeder of the TWAIN source, call the LTwain::StopFeeder within the LTwain::BitmapCallBack function when its fired.

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

class CMyTwainA : public LTwain
{
public:
   L_INT BitmapCallBack(pBITMAPHANDLE pBitmap);
   HTWAINTEMPLATEFILE m_hFile;
};
L_INT CMyTwainA::BitmapCallBack(pBITMAPHANDLE pBitmap)
{
   UNREFERENCED_PARAMETER(pBitmap);
   // You can do here any processing to the bitmap
   return SUCCESS;
}
// initialize session and call this function 
L_INT LTwain__AcquireExample(pBITMAPHANDLE pBitmap, HWND hWnd) 
{
   UNREFERENCED_PARAMETER(hWnd);
   L_INT          nRet; 
   TW_CAPABILITY  twCap;
   CMyTwainA       MyClass;
   // Show the Twain Select Source UI
   nRet = MyClass.SelectSource(NULL);
   if (nRet != SUCCESS) 
   {
      MessageBox (NULL, TEXT("Error occurred while selecting the source."), TEXT("ERROR"), MB_OK); 
      return nRet;
   }
   twCap.Cap = ICAP_XFERMECH; 
   twCap.ConType = TWON_ONEVALUE;
   nRet = MyClass.CreateNumericContainerOneValue(&twCap, TWAINNUMERICTYPE_TW_UINT16, TWSX_NATIVE);
   if(nRet != SUCCESS)
      return nRet;
   nRet = MyClass.SetCapability( &twCap, LTWAIN_CAPABILITY_SET);
   if(nRet != SUCCESS)
      return nRet;
   nRet = MyClass.FreeContainer(&twCap);
   if(nRet != SUCCESS)
      return nRet;
  MyClass.EnableCallBack (TRUE);
   nRet = MyClass.Acquire( pBitmap, sizeof(BITMAPHANDLE), LTWAIN_SHOW_USER_INTERFACE, 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;
}