Newsgroups: borland.public.delphi.graphics
Subject: Flip a bitmap (One way to do it).
From: None@Noware.non (Johnnie)
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Date: 7 Feb 2002 10:36:26 -0800
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Hi all,

Playing around with the Windows API
I created this general procedure
to flip an image either horizontally,
vertically or both at once.


Interface
Uses Graphics;

Type
TMirror = (MT_Horizontal,MT_Vertical,MT_Both);

Procedure Flip(MirrorType:TMirror;BMp:Graphics.TBitmap);
implementation

{$R *.dfm}
Procedure Flip(MirrorType:TMirror;BMP:Graphics.TBitMap);
Var
  Dest :TRect;
begin
  if assigned(BMP) then
    Case MirrorType of
      MT_Horizontal : begin
                        Dest.Left := RotateBmp.Width;
                        Dest.Top := 0;
                        Dest.Right := - RotateBmp.Width;
                        Dest.Bottom := RotateBmp.Height;
                      end;
      MT_Vertical   : Begin
                        Dest.Left := 0;
                        Dest.Top := RotateBmp.Height;
                        Dest.Right := RotateBmp.Width;
                        Dest.Bottom := - RotateBmp.Height;
                      end;
      MT_Both       : begin
                        Dest.Left := RotateBmp.Width;
                        Dest.Top := RotateBmp.Height;
                        Dest.Right := -RotateBmp.Width;
                        Dest.Bottom := - RotateBmp.Height;
                      end;
    end;
    stretchblt(BMP.Canvas.Handle,Dest.Left,DEst.Top,Dest.Right,Dest.Bottom,
               BMP.Canvas.Handle,0,0,MemBmp.Width,membmp.Height,SRCCOPY);
  end;
end;


It is fast enough and it can be used in
any type of image (PF8bit,pf24bit,pf4bit etc).

Have Fun.

Regards
Johnnie.