L_WiaGetPropertyString

#include "ltwia.h"

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

HWIASESSION hSession;	/* handle to an existing WIA session */
L_VOID* pItem;	/* pointer to IWiaItem or IWiaItem2 interface */
L_TCHAR* pszID;	/* pointer to string array that represents the equivalent property ID string */
L_UINT32 uID;	/* property ID */
L_TCHAR* pszValue;	/* pointer to a string buffer to be updated */
L_SIZE_T* puLength;	/* pointer to a variable that contains the user allocated string buffer length */

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

Parameter	Description
hSession	Handle to an existing WIA session. This handle is obtained by calling the L_WiaInitSession function.
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.
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.
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.
pszValue	Pointer to an allocated string buffer to be updated with the property ID of the provided item.
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

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

Earlier and later operating systems than Windows XP for WIA Version 1.

Windows VISTA or later for WIA Version 2.

See Also

Functions:	L_WiaGetPropertyLong, L_WiaGetPropertyBuffer, L_WiaGetPropertyGUID, L_WiaGetPropertySystemTime, L_WiaGetRootItem, L_WiaEnumChildItems, L_WiaInitSession, L_WiaEndSession.
Topics:	Managing WIA Sources
	WIA Functionality: Property Functions

Example

L_LTWIATEX_API 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;
}