LWia::AcquireCallBack

#include "ltwrappr.h"

virtual L_INT LWia::AcquireCallBack(pBitmap, pszFilename, uPercent, uFlags)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_TCHAR * pszFilename;	/* file name */
L_UINT32 uPercent;	/* the percent completion of the acquire process */
L_UINT32 uFlags;	/* flags that indicates whether the device finished acquiring the page */

This function will be called after calling any of the LWia::Acquire or LWia::AcquireSimple functions. And it will be enabled only if you enabled the callback functions by calling LBase::EnableCallBack (TRUE).

Parameter	Description
pBitmap	Pointer to the bitmap handle that references the bitmap acquired from the WIA source.
pszFilename	Character string containing the name of the file to which to save the scanned image(s). This parameter is valid only if the transfer mode is set to file transfer.
uPercent	The percent completion of the page being scanned.
uFlags	Flag that indicates the start or the end of the scanned page. Possible values are:
	Value	Meaning
	0	Default value when this is not the first transferred chunk or the last transferred chunk.
	L_WIA_ACQUIRE_START_OF_PAGE	[0x00000001] Indicates the start of the page being scanned.
	L_WIA_ACQUIRE_END_OF_PAGE	[0x00000002] Indicates the end of the page being scanned. Use this value to reset the progress bar.

Returns

SUCCESS	The function was successful.
ERROR_USER_ABORT	The callback wants to abort the scanning operation.
< 1	An error occurred. Refer to Return Codes.

Comments

This feature is available in LEADTOOLS version 16 or higher.

This callback will be called through the acquire process to provide the user with the percent completed of the process so he can update his progress bar and at the end it provides him/her with the bitmap handle after its prepared (if the user is doing memory transfer) and also passes the user the L_WIA_ACQUIRE_END_OF_PAGE flag in the uFlags parameter to indicate each end of page.

To prevent memory leaks, the user should free the bitmap within the callback function.

Note:

If you are using WIA 2.0 while the L_WIA_SHOW_USER_INTERFACE is set then no need to provide a callback pointer since Microsoft’s WIA 2.0 acquire dialog doesnt provide a callback and it does all the process and return back to you with the saved files count and paths.

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.

Functions:	LWia::Acquire, LWia::AcquireToFile, LWia::AcquireSimple, LWia::InitSession, LWia::EndSession, Class Members
Topics:	How to Acquire from the WIA Source
	WIA Functionality: Property Functions
	WIA Functionality: Callbacks