Delphi 使用MD5 比对文件

使用MD5的方法比对CXimage里图片是否改变：

Delphi7实现方法：

uses IdHashMessageDigest 

function TForm1.GetImageMD5(cxImage: TcxImage): string;
var
  tmpMD5: TIdHashMessageDigest5;
  ms: TMemoryStream;
begin
  result:='';
  if cxImage.Picture.Graphic=nil then exit;
  tmpMD5:=TIdHashMessageDigest5.Create;
  ms:= TMemoryStream.Create;
  try
    cxImage.Picture.Graphic.SaveToStream(ms);
    result:=tmpMD5.AsHex(tmpMD5.HashValue(ms));
  finally
    tmpMD5.Free;
    ms.Free;
  end;
end;

Delphi2010实现方法：

uses IdHashMessageDigest

function GetImageMD5(cxImage: TcxImage): string;
var
  tmpMD5: TIdHashMessageDigest5;
  ms: TMemoryStream;
begin
  result:='';
  if cxImage.Picture.Graphic=nil then exit;
  tmpMD5:=TIdHashMessageDigest5.Create;
  ms:= TMemoryStream.Create;
  try
    cxImage.Picture.Graphic.SaveToStream(ms);
    ms.Position:=0;
    result:=tmpMD5.HashStreamAsHex(ms);
  finally
    tmpMD5.Free;
     ms.Free;
  end;
end;

参考：http://www.cnblogs.com/jxsoft/archive/2011/08/08/2131436.html