L_TwainInitSession2

Summary

Initializes the TWAIN session.

Syntax

L_LTTWN_API L_INT L_TwainInitSession2(phSession, pAppData, uFlags)

Parameters

pHTWAINSESSION phSession

Pointer to a TWAIN session handle.  This handle is needed to acquire pages from the TWAIN source, and work with template files, containers, capabilities, and properties.

pAPPLICATIONDATA pAppData

Pointer to an APPLICATIONDATA structure. This structure will have the handle of the parent window, in addition to other data about the application.

L_UINT uFlags

Flags that indicate the function behavior.  Possible values are:

Returns

Comments

L_TwainInitSession2 (or L_TwainInitSession) must be called before calling any other LEADTOOLS TWAIN toolkit functions.

When the handle to the TWAIN session is no longer needed, free it by calling L_TwainEndSession. Every call to L_TwainInitSession2 requires a call to L_TwainEndSession when the session is no longer needed.

When passing LTWAIN_INIT_USE_THUNKSERVER to uFlags, it detects and interacts with a 32-bit TWAIN driver or device from a 64-bit process application.
Pass this value only when using a TWAIN device that does not have a 64-bit driver and the operating system is 64-bit. When using the THUNK server be sure to include in the redistributables for the application all dependency files listed in the Using the LEADTOOLS THUNK Utility with TWAIN.

TWAIN Specification Support

LEADTOOLS TWAIN toolkits support both the TWAIN 1.9 and the TWAIN 2.x specifications. By default the toolkit will check whether the current selected TWAIN data source is TWAIN 2.x compliant and try to load the TWAIN 2.x DLL (TWAINDSM.DLL) if it exists in the system. The TWAIN version will be "TWAIN_VERSION2".

If that fails or if the scanner is not compatible with TWAIN 2.x, the toolkit will try to start TWAIN 1.9 (Twain_32.DLL) from your system. The TWAIN version will be "TWAIN_VERSION1".

You can also override the default behavior and explicitly set which version of TWAIN the selected device will use. To do so, call L_TwainSetVersion and pass "TWAIN_VERSION1" to use version 1.9, or "TWAIN_VERSION2" to use version 2.x. For more information, refer to Setting which TWAIN Specification Version to use and Managing the TWAIN Source.

Call L_TwainGetVersion to determine which TWAIN specification is currently being used by the LEADTOOLS TWAIN toolkit.                  

Note: When using the thunk server, working on a 64-Bit operating system, and using a TWAIN device without a 64-Bit driver, it is preferred to pass NULL to hWnd in pAppData parameter.

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.

TWAIN Session Behavior

A TWAIN session is a communication session between LEADTOOLS Twain and your TWAIN sources. The internal TWAIN session handle provides access to this TWAIN session.

• For further details of the process flow summarizing the default behavior, refer to Startup2 Method: Default Behavior.
• For further details of the process flow summarizing the function's behavior when passing specific flags, refer to Startup2 Method: Using the Thunk Server.

See Also

Functions

• L_TwainEndSession
• L_TwainInitSession
• L_TwainGetVersion
• L_TwainSetVersion

Topics

• Initializing a TWAIN Session
• TWAIN Functionality: Session Functions
• Programming with the LEADTOOLS TWAIN Functions
• Using LEADTOOLS THUNK Utility with TWAIN
• Setting which TWAIN Specification Version to use

Example

L_INT TwainInitSession2Example(HWND hWnd,HBITMAPLIST hBitmap) 
{ 
   L_INT nRet; 
   L_BOOL bAvailable; 
   HTWAINSESSION hSession = NULL; 
   APPLICATIONDATA AppData; 
 
   /* Check to see if TWAIN is installed */ 
   bAvailable = L_IsTwainAvailable(hWnd); 
  
   if (bAvailable)  
   { 
      AppData.hWnd = hWnd; 
      AppData.uStructSize = sizeof(APPLICATIONDATA); 
      lstrcpy (AppData.szManufacturerName, TEXT("LEAD Technologies, Inc.")); 
      lstrcpy (AppData.szAppProductFamily, TEXT("LEAD Test Applications")); 
      lstrcpy (AppData.szVersionInfo, TEXT("Version 1.0")); 
      lstrcpy (AppData.szAppName, TEXT("TWAIN Test Application")); 
      nRet = L_TwainInitSession2(&hSession, &AppData, LTWAIN_INIT_MULTI_THREADED); 
      if (nRet != SUCCESS) 
         return nRet; 
 
      nRet = L_TwainAcquireList(hSession, hBitmap, NULL, LTWAIN_SHOW_USER_INTERFACE); 
      if(nRet != SUCCESS) 
         return nRet; 
      nRet = L_TwainEndSession(&hSession); 
      if(nRet != SUCCESS) 
         return nRet; 
   } 
   return SUCCESS; 
}