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L_ScrambleBitmap

Summary

Scrambles all or a portion of a bitmap.

Syntax

#include "l_bitmap.h"

L_LTKRN_API L_INT L_ScrambleBitmap(pBitmap, nColStart, nRowStart, nWidth, nHeight, uKey, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to a bitmap handle for the bitmap to be scrambled.

L_INT nColStart

Starting column in pixels (0-based).

L_INT nRowStart

Starting row in pixels (0-based).

L_INT nWidth

Width of area to scramble in pixels.

L_INT nHeight

Height of area to scramble in pixels.

L_UINT uKey

Key that determines the scramble. This is an unsigned integer with a minimum value of 0 and a maximum value of 4294967295 (0xffffffff).

L_UINT uFlags

Flag that determines whether to encrypt or decrypt the area. Possible values are:

Value	Meaning
SB_ENCRYPT	Encrypts the area (the reverse of a decrypt).
SB_DECRYPT	Decrypts the area (the reverse of an encrypt).
SB_INTERSECT	Intersect the specified rectangle with the bitmaps rectangle.

Returns

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

Comments

Scrambling a rectangular area means that the pixels in that area are shuffled around into a pseudo-random location within the area.

Some properties of shuffling:

No colors are introduced,

Color counts remain unchanged

Given the same encrypt area (defined by nColStart, nRowStart, nWidth, nHeight) and the same key, setting (uFlags = SB_ENCRYPT) is the inverse of (uFlags = SB_DECRYPT)

Required DLLs and Libraries

LTKRN
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

Win32, x64, Linux.

Example

This example scrambles the upper left quadrant of a bitmap
using the key 123

L_INT ScrambleBitmapExample(pBITMAPHANDLE pBitmap) 
{ 
   L_INT nRet; 
 
   if (!pBitmap) 
      return ERROR_NO_BITMAP; 
 
   nRet = L_ScrambleBitmap(pBitmap, 0, 0, BITMAPWIDTH(pBitmap)/2, BITMAPHEIGHT(pBitmap)/2, 123, SB_ENCRYPT); 
   if(nRet != SUCCESS) 
      return nRet; 
   return SUCCESS; 
}