Delphi 模拟网站验证码（酷，把随机文字写道图片上）

function TfrmLabelPages.PwdImg(img: Timage): string;  
var  
  I,j,k:   Integer;  
  vPoint:   TPoint;  
  vLeft:   Integer;  
  arrStr:array [1..36]of string ;  
  strResult: string;  
begin  
  strResult := '';  
  arrStr[1] := '0';  arrStr[2]:='1';  arrStr[3]:='2';  arrStr[4]:='3';  
  arrStr[5] := '4';  arrStr[6]:='5';  arrStr[7]:='6';  arrStr[8]:='7';  
  arrStr[9] := '8';  arrStr[10]:='9'; arrStr[11]:='A'; arrStr[12]:='B';  
  arrStr[13] := 'C'; arrStr[14]:='D'; arrStr[15]:='E'; arrStr[16]:='F';  
  arrStr[17] := 'G'; arrStr[18]:='H'; arrStr[19]:='I'; arrStr[20]:='J';  
  arrStr[21] := 'K'; arrStr[22]:='L'; arrStr[23]:='M'; arrStr[24]:='N';  
  arrStr[25] := 'O'; arrStr[26]:='P'; arrStr[27]:='Q'; arrStr[28]:='R';  
  arrStr[29] := 'S'; arrStr[30]:='T'; arrStr[31]:='U'; arrStr[32]:='V';  
  arrStr[33] := 'W'; arrStr[34]:='X'; arrStr[35]:='Y'; arrStr[36]:='Z';  
  For j:=1 to 4  do  
  begin  
    Randomize;  
    k := strtoint(Format('%.1d',[Random(36)]));  
    strResult := strResult + trim(arrStr[k])  
  end;  
  vLeft := 10;  
  img.picture := nil;  
  for I := 1 to Length(strResult) do  
  begin  
    with Img do  
    begin  
      Canvas.Font.Size := Random(10)+ 9;  
      Canvas.Font.Color := RGB(Random(256) and $C0,  
      Random(256) and $C0, Random(256) and $C0);  
      if Random(2)=1 then  
        Canvas.Font.Style := [fsBold]  
      else Canvas.Font.Style := [];  
      begin  
        Canvas.Font.Name := Screen.Fonts[10];  
        vPoint.X := Random(4)+ vLeft;  
        vPoint.Y := Random(5);  
        Canvas.TextOut(vPoint.X, vPoint.Y,strResult[I]);  
        vLeft := vPoint.X + Canvas.TextWidth(strResult[I]);  
      end;  
    end;  
  end;  
end;  

http://blog.csdn.net/yanjiaye520/article/details/7957397