LBitmap::Scramble

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#include "ltwrappr.h"

virtual L_INT LBitmap::Scramble (nColStart, nRowStart, nWidth, nHeight, uKey, uFlags)

L_INT32 nColStart;	/* starting column in pixels (0-based)*/
L_INT32 nRowStart;	/* starting row in pixels (0-based)*/
L_INT32 nWidth;	/* width of area to scramble in pixels */
L_INT32 nHeight;	/* height of area to scramble in pixels */
L_UINT32 uKey;	/* key that determines the scramble */
L_UINT uFlags;	/* flag that determines whether to encrypt or decrypt the area */

Scrambles all or a portion of a bitmap.

Parameter	Description
nColStart	Starting column in pixels (0-based).
nRowStart	Starting row in pixels (0-based).
nWidth	Width of area to scramble in pixels.
nHeight	Height of area to scramble in pixels.
uKey	Key that determines the scramble. This is an unsigned integer with a minimum value of 0 and a maximum value of 4294967295 (0xffffffff).
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 rect with the bitmap©s rect.

Returns

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.

See Also

Functions:	LAnnEncrypt::GetEncryptOptions, LAnnEncrypt::SetEncryptOptions, Class Members
Topics:	Annotation Functions: Object Properties
	Implementing Annotations
	Automated User Interface for Annotations
	Annotation Functions: Creating and Deleting Annotations
	Types of Annotations

Example

L_INT LBitmap__ScrambleExample(LBitmap *pLBitmap) 
{
   if (!pLBitmap->IsAllocated())
      return FAILURE; 
  
   return pLBitmap->Scramble(0, 
                            0, 
                            pLBitmap->GetWidth()/2, 
                            pLBitmap->GetHeight()/2, 
                            123, 
                            SB_ENCRYPT); 
}