Re: Optimize this code

On Mon, 18 Aug 2003 07:44:17 +0700, dk wrote:

>Hi all,
>Is there anyone can optimize this code?
>I'm making a steganography program based on LSB insertion bit, I think the problem is in the use of property pixels from TCanvas. It's too slow. HEre's the code: 
>
>procedure TStegoStream.SetBit(Value: Integer);
>var
>  NewColor: TColor;
>  Pos: Integer;
>  R: PRGBTripleArray;
>begin
>  NewColor := BMP.Canvas.Pixels[X, Y];
>  Value := Value and 1;
>  Pos := ColorPos * 8 + BitPos;
>  NewColor := NewColor and not(1 shl Pos);
>  NewColor := NewColor or (Value shl Pos);
>  BMP.Canvas.Pixels[X, Y] := NewColor;
>  NextBit;
>end;

Here's one idea - it should be faster

procedure TStegoStream.SetBit(Value: Integer);
begin
	Value := (Value and 1) Shl (ColorPos * 8 + BitPos);
	BMP.Canvas.Pixels[X, Y] := 
		(BMP.Canvas.Pixels[X, Y] and not Value) or Value;
	NextBit;
end;

-- 
Regards,
Allan Smith (Northwood, Middlesex, England)

------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for Your HP, Epson, Canon or Lexmark
Printer at Myinks.com. Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/l.m7sD/LIdGAA/qnsNAA/i7folB/TM
---------------------------------------------------------------------~->

Delphi VCL Top Sites!
http://www.sandbrooksoftware.com/TS/TS2/Components.shtml
---------------------------------------------------------------
Unsubscribe:[email protected]
List owner:[email protected]
--------------------------------------------------------------- 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/