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L_WiaGetPropertyString

Summary

Retrieves a string buffer for any WIA property of type VT_BSTR.

Syntax

#include "ltwia.h"

L_LTWIA_API L_INT EXT_FUNCTION L_WiaGetPropertyString(hSession, pItem, pszID, uID, pszValue, puLength)

Parameters

HWIASESSION hSession

Handle to an existing WIA session. This handle is obtained by calling the L_WiaInitSession function.

L_VOID* pItem

Valid pointer to a type IWiaItem or IWiaItem2 object (IWiaItem if using WIA Version 1.0; IWiaItem2 if using WIA Version 2.0), which represents the item having the property.

You can retrieve this parameter by either calling the L_WiaGetRootItem function to get a pointer to the device's root item or by enumerating the child items of the device through a call to L_WiaEnumChildItems.

L_TCHAR* pszID

This string pointer should contain the equivalent property ID string for the WIA property ID (see example below):

Property ID	Property ID Equivalent String
WIA_IPA_TYMED	WIA_IPA_TYMED_STR or "Media Type"
WIA_IPA_DEPTH	WIA_IPA_DEPTH_STR or "Bits Per Pixel"

If this parameter is NULL then the WIA toolkit will use the ID passed through the uID parameter; otherwise the pszID parameter will be used whether or not a valid property ID is passed through the uID parameter.

L_UINT32 uID

The property ID for the WIA property.

This parameter is required only if the pszID parameter is NULL; otherwise you can pass 0 for this parameter.

L_TCHAR* pszValue

Pointer to an allocated string buffer to be updated with the property ID of the provided item.

L_SIZE_T* puLength

Pointer to a variable that contains the user allocated string buffer length. This parameter will always be updated with the exact required string buffer length.

Returns

Value	Meaning
SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

This feature is available in version 16 or higher.

Any WIA property of type VT_BSTR (like WIA_DIP_DEV_NAME, WIA_IPA_FULL_ITEM_NAME, etc) returns a string buffer. To retrieve a string buffer you need to call the function L_WiaGetPropertyString after allocating a string buffer of type L_TCHAR and passing a pointer to that allocated string buffer.

To retrieve the required string buffer length, declare a variable of type L_SIZE_T and pass the address of that variable to this function and also pass NULL for the pszValue parameter. Then use the returned buffer length to allocate the string buffer with the exact required buffer length.

Required DLLs and Libraries

LTWIA
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

LEADTOOLS WIA supports both 32-bit and 64-bit image acquisition for both WIA 1.0 (XP and earlier) and WIA 2.0 (VISTA and later).

Example

L_INT WiaGetPropertyStringExample(HWIASESSION hSession, HWND hWnd) 
{ 
   L_INT nRet; 
   L_TCHAR szArtist[MAX_PATH] = TEXT(""); 
   L_SIZE_T uLength = MAX_PATH; 
   IWiaItem * pRootItem = NULL; 
 
   nRet = L_WiaSelectDeviceDlg(hSession, hWnd, WiaDeviceTypeDefault, 0); 
   if(nRet != WIA_SUCCESS) 
      return nRet; 
 
   nRet = L_WiaGetRootItem(hSession, NULL, (L_VOID**)&pRootItem); 
   if(nRet != WIA_SUCCESS) 
      return nRet; 
 
   // if you have a digital camera device that supports EXIF format, then you  
   // can populate the artist field in every EXIF image that it captures. 
   nRet = L_WiaGetPropertyString(hSession, pRootItem, NULL, WIA_DPC_ARTIST, szArtist, &uLength); 
   if(nRet != WIA_SUCCESS) 
      return nRet; 
 
   // You can also change the artist if you like to. 
   lstrcpy(szArtist, TEXT("I am the artist.")); 
   nRet = L_WiaSetPropertyString(hSession, pRootItem, NULL, WIA_DPC_ARTIST, szArtist); 
   if(nRet != WIA_SUCCESS) 
      return nRet; 
 
   return SUCCESS; 
}