L_TwainAcquireMulti

Summary

Acquires one or more images from a TWAIN source and stores the images in the specified file(s).

Syntax

L_LTTWN_API L_INT L_TwainAcquireMulti(hSession, pszBaseFileName, uFlags, uTransferMode, nFormat, nBitsPerPixel, bMultiPageFile, uUserBufSize, bUsePreferredBuffer, pfnCallBack, pUserData)

Parameters

HTWAINSESSION hSession

Handle to an existing TWAIN session. This handle is obtained by calling the L_TwainInitSession or L_TwainInitSession2 function.

L_TCHAR *pszBaseFileName

Character string containing the base name of the image file(s) in which to save the acquired data.

L_UINT uFlags

Flag that determines certain actions of the TWAIN source. Possible values are:

L_UINT uTransferMode

Flag that indicates the transfer mode to use when acquiring the image(s). Possible values are:

L_INT nFormat

Output file format. Valid values depend on the transfer mode used.

• For valid values for the File transfer mode, refer to the values for the uFileFormat member of the TRANSFEROPTIONS structure.
• For valid values for the Memory and Native transfer modes, refer to Formats of Output Files.

L_INT nBitsPerPixel

Resulting file's pixel depth. Note that not all bits per pixel are available to all file formats. For valid values, refer to Formats of Output Files.

If nBitsPerPixel is 0, the file will be stored using the closest BitsPerPixel value supported by that format.

L_BOOL bMultiPageFile

Flag that indicates whether to save multiple images into a single multipage file, or into a series of single page files. Possible values are:

If the file format specified in nFormat does not support multipage files, the value of bMultiPageFile will be ignored and the function will automatically save the acquired images in separate files.

The naming of the files will be carried out as follows:

• If the string in pszBaseFileName is "Temp.jpg", the method will append the number of the image (0001, 0002, etc.), to the name of the file. Therefore, the output file names will be "Temp0001.jpg", "Temp0002.jpg", etc.

• Should more than 9,999 pages be acquired, numbering switches to using the actual page number. So after "Temp9999.jpg", the next page scanned would be named "Temp10000.jpg", and the following page would be "Temp10001.jpg", etc. After "Temp99999.jpg", the next page scanned would be named "Temp100000.jpg", and the following page would be "Temp100001.jpg", etc.

If the file format supports multipage files, this function will use the bMultiPageFile parameter to determine how to save multiple images.

• If bMultiPageFile is FALSE, each scanned page will be saved to a separate file, named in the same manner described in the paragraph above.

• If bMultiPageFile is TRUE, the name of the output file will be the exact string used in pszBaseFileName (e.g., "Temp.jpg") and it will be saved as a multipage file.

L_UINT32 uUserBufSize

Specifies a user-defined buffer size. This value will be used if uTransferMode is LTWAIN_BUFFER_MODE and the bUsePreferredBuffer parameter is FALSE. This value must be a multiple of 16.

L_BOOL bUsePreferredBuffer

Flag that indicates whether to use the user-defined buffer size or the TWAIN driver preferred buffer size. Possible values are:

LTWAINACQUIRECALLBACK pfnCallBack

Optional callback function, called twice for each page scan. The 1st call is to notify the page is start scanning, and the 2nd call is to notify the page scanning is finished.

If you do not provide a callback function, use NULL as the value of this parameter. No error reporting will occur.

If you do provide a callback function, use the function pointer as the value of this parameter. The callback function must adhere to the function prototype described in the LTWAINACQUIRECALLBACK function.

L_VOID * pUserData

Void pointer that you can use to pass one or more additional parameters that the callback function needs.

To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID *.

The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure.

Returns

Comments

This function will acquire one or more images from a TWAIN source and store the images to the specified file(s).

• Before calling this function, you can call L_TwainFindFastConfig to determine the best/fastest scan configuration based on the scanner type, and then pass the scan configuration information to the L_TwainAcquireMulti function.

• If you do not call L_TwainFindFastConfig before calling L_TwainAcquireMulti, then the L_TwainAcquireMulti function will determine the best/fastest scanning method based on the scanner type.

If the file format specified in nFormat does not support multipage files, the value of bMultiPageFile will be ignored and the function will automatically save the acquired images in separate files. The naming of the files will be carried out as follows:

• If the string in pszBaseFileName is "Temp.jpg", the method will append the number of the image (0001, 0002, etc.), to the name of the file. Therefore, the output file names will be "Temp0001.jpg", "Temp0002.jpg", etc.

• Should more than 9,999 pages be acquired, numbering switches to using the actual page number. So after "Temp9999.jpg", the next page scanned would be named "Temp10000.jpg", and the following page would be "Temp10001.jpg", etc. After "Temp99999.jpg", the next page scanned would be named "Temp100000.jpg", and the following page would be "Temp100001.jpg", etc.

If the file format specified in nFormat supports multipage files, this function will use the bMultiPageFile parameter to determine how to save multiple images.

• If bMultiPageFile is FALSE, each scanned page will be saved to a separate file, named in the same manner described in the paragraph above.

• If bMultiPageFile is TRUE, the name of the output file will be exactly the string in pszBaseFileName (Temp.jpg) and it will be saved as a multipage file.

If uTransferMode is LTWAIN_BUFFER_MODE, and bUsePreferredBuffer  is FALSE, then the function will use the user-defined buffer size in uUserBufSize.

If, however, bUsePreferredBuffer is TRUE, then the function will use the TWAIN driver preferred buffer size and will ignore uUserBufSize.

To cancel the acquire operation call L_TwainCancelAcquire.

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

The LTWAIN_KEEPOPEN flag works only in the following cases:

1. Passed with LTWAIN_SHOW_USER_INTERFACE flag to make the TWAIN user-interface appear as a modeless dialog. The TWAIN data source remains open after scanning until the user closes it.

2. Passed with LTWAIN_SHOW_USER_INTERFACE and LTWAIN_MODAL_USER_INTERFACE flags to make the TWAIN user-interface appear as a modal dialog. The TWAIN data source remains open after scanning until the user closes it.

Required DLLs and Libraries

• LTTWN
• For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files to be Included with your Application.

See Also

Functions

• L_TwainAcquire
• L_TwainAcquireList
• L_TwainInitSession
• L_TwainEndSession
• L_TwainOpenTemplateFile
• L_TwainCloseTemplateFile
• L_TwainTemplateDlg
• L_TwainAddCapabilityToFile
• L_TwainGetNumofCapsInFile
• L_TwainGetCapabilityFromFile
• L_TwainFindFastConfig
• L_TwainGetScanConfigs
• L_TwainFreeScanConfig
• L_TwainCancelAcquire
• L_TwainStopFeeder
• L_TwainFastAcquire

Topics

• How to Acquire from the TWAIN Source
• TWAIN Functionality: Property Functions

Example

For complete sample, refer to FASTTWN
demo.

L_VOID EXT_CALLBACK AcquireMultiCB(HTWAINSESSION hSession, 
                                   L_INT         nPage, 
                                   L_TCHAR*      pszFileName, 
                                   L_BOOL        bFinishScan, 
                                   L_VOID*       pUserData) 
{ 
   UNREFERENCED_PARAMETER(hSession); 
   UNREFERENCED_PARAMETER(pUserData); 
 
   L_TCHAR szTemp[MAX_PATH]; 
   if (bFinishScan) 
   { 
      wsprintf(szTemp, TEXT("The page # %d is scanned and saved to file name %s\n"), nPage, pszFileName); 
      MessageBox(NULL, szTemp, TEXT("Notice"), MB_OK); 
   } 
} 
 
L_INT TwainAcquireMultiExample(HWND hWnd,HTWAINSESSION hSession) 
{ 
   L_INT nRet; 
 
   nRet = L_TwainAcquireMulti(hSession, 
                              MAKE_IMAGE_PATH(TEXT("test.tif")), 
                              LTWAIN_SHOW_USER_INTERFACE, 
                              LTWAIN_BUFFER_MODE, 
                              FILE_TIF, 
                              1, 
                              TRUE, 
                              0,  
                              FALSE, 
                              AcquireMultiCB, NULL); 
 
   if (nRet == SUCCESS) 
      MessageBox(hWnd, TEXT("Fast Twain function was successful"), TEXT("Notice"), MB_OK); 
   else 
      MessageBox(hWnd, TEXT("Error occurred during fast Twain function!!!"), TEXT("Error!!!"), MB_OK); 
 
   return nRet; 
}