LTwain::FindFastConfig

#include "ltwrappr.h"

virtual L_INT LTwain::FindFastConfig(pszWorkingFolder, uFlags, nBitsPerPixel, nBufferIteration, pInFastConfigs, nInFastConfigsCount, ppTestConfigs, pnTestConfigsCount, pOutBestConfig, uStructSize)

Determines the best scanner configuration.

This function is available in the Document/Medical Toolkits.

Returns

Comments

This function will test scan configurations for the scanner selected by calling LTwain::SelectSource. It will update the pOutBestConfig parameter with the best scan configuration tested. Once the best scan configuration has been determined, the scan configuration's values for the transfer mode, bits per pixel, format and buffer size can be passed to LTwain::AcquireMulti or LTwain::FastAcquire so the images can be scanned as fast as possible.

To test user-defined/custom configurations, pass these configurations in pInFastConfigs and the number of configurations in nInFastConfigsCount.

To test the default configurations available for the Twain driver, pass NULL for pInFastConfigs and 0 for nInFastConfigsCount. In this case, the function will test scan configurations based the values passed in the nBitsPerPixel and nBufferIteration parameters.

The list of default scan configurations to test can be shortened by using the LTwain::GetScanConfigs function to get a list of default scan configurations based on transfer mode, bits per pixel and number of buffers. This list can then be passed to LTwain::FindFastConfig function to determine the best and fastest scan configuration.

If LTWAIN_CHECK_ALL_DEFAULT_BPP is set in uFlags then the function will test all supported bits per pixel for the selected scanner. If this flag is not set in uFlags, then the function will use the iBitsPerPixel parameter value.

If LTWAIN_USE_THREAD_MODE is set in uFlags, then the image acquisition process will run in thread mode. In some scanners, acquiring images in thread will improve the speed at which the image(s) is(are) acquired. In other scanners, high-speed scanners, for example, acquiring the image(s) in thread mode will provide little to no improvement in the speed at which the image(s) is(are) acquired.

The nBitsPerPixel parameter and LTWAIN_CHECK_ALL_DEFAULT_BPP flag will be used only if the transfer mode for the scan configuration being tested is LTWAIN_BUFFER_MODE or LTWAIN_NATIVE_MODE.

The nBufferIteration parameter will be used only if the transfer mode for the scan configuration being tested is LTWAIN_BUFFER_MODE.

If you override the LTwain::FindFastConfigCallBack function, the scan configuration testing process can be stopped by returning any value other than SUCCESS for the callback function. The testing process is continued by returning SUCCESS for the callback function.

This function allocates storage for the array of scan configurations in ppTestConfigs. When this storage is no longer needed, you must free the storage by calling LTwain::FreeScanConfig.

The LTWAIN_KEEPOPEN flag works only in the following cases:

Required DLLs and Libraries

See Also

Example

// initialize session by LTwain::InitSession and call this function
L_INT CMyTwain::FindFastConfigCallBack(pFASTCONFIG pResConfig)
{
   L_TCHAR szBuffer[MAX_PATH];
   if (pResConfig->bSuccess)
   {
      memset(szBuffer, 0, sizeof(szBuffer));
      wsprintf(szBuffer, TEXT("Transfer Mode = %d\nFile Format = %d\nBuffer Size = %d\nRequired Time = %d\n"),
            pResConfig->uTransferMode,
            pResConfig->nFileFormat,
            pResConfig->ulBufferSize,
            pResConfig->uTime);
      MessageBox(NULL, szBuffer, TEXT("Result Scan Configuration..."), MB_OK);
   }
   else
      MessageBox(NULL, TEXT("The tested configuration failed"), TEXT("Error!"), MB_OK);
   return SUCCESS;
}
L_INT LTwain__FindFastConfigExample(HWND hWnd, CMyTwain *MyClass)
{
   L_INT       nRet;
   pFASTCONFIG pTestConfigs = NULL;
   L_INT       nTestConfigsCount = 0;
   pFASTCONFIG pFastConfig=NULL;
   L_INT       nFastConfigCount;
   FASTCONFIG  BestConfig;
   L_TCHAR     szBuffer[MAX_PATH];
   MyClass->EnableCallBack (TRUE);
   nRet = MyClass->GetScanConfigs (1, LTWAIN_BUFFER_MODE, 5, &pFastConfig, sizeof(FASTCONFIG), &nFastConfigCount);
   if (nRet != SUCCESS)
   {
      MessageBox(hWnd, TEXT("Error occurred while getting the scan configurations for the Memory transfer mode!!!"), TEXT("Error!!!"), MB_OK);
      return nRet;
   }
   memset(&BestConfig, 0, sizeof(FASTCONFIG));
   nRet = MyClass->FindFastConfig(TEXT("c:\\TWAIN"),
                                  LTWAIN_SHOW_USER_INTERFACE,
                                  1,
                                  5,
                                  pFastConfig, nFastConfigCount,
                                  &pTestConfigs,
                                  &nTestConfigsCount,
                                  &BestConfig, sizeof(FASTCONFIG));
   if (nRet == SUCCESS)
   {
      MessageBox(hWnd, TEXT("LTwain::FindFastConfig function was successful."), TEXT("Notice"), MB_OK);
      memset(szBuffer, 0, sizeof(szBuffer));
      wsprintf(szBuffer, TEXT("Transfer Mode = %d\nFile Format = %d\nBuffer Size = %d\nRequired Time = %d\n"),
               BestConfig.uTransferMode,
               BestConfig.nFileFormat,
               BestConfig.ulBufferSize,
               BestConfig.uTime);
      MessageBox(hWnd, szBuffer, TEXT("Best Scan Configuration..."), MB_OK);
      MyClass->FreeScanConfig(&pTestConfigs, nTestConfigsCount);
   }
   else
   {
      MessageBox(hWnd, TEXT("Error occurred in the L_TwainFindFastConfig function!!!"), TEXT("Error!!!"), MB_OK);
      return nRet;
   }
   nRet = MyClass->FreeScanConfig(&pFastConfig, nFastConfigCount);
   if(nRet != SUCCESS)
      return nRet;
   return SUCCESS;
}