前辈的两组代码，请较详细的解释每句的意思（除了var,begin,end等句）

Question

var
pjpg:tjpegimage;
pic:TMemoryStream;
begin
pjpg:=tjpegimage.Create;
pjpg.LoadFromFile(F:\JPG.jpg);
pic:=TMemoryStream.Create;
pjpg.SaveToStream(pic);
pic.Position:=0;
TBlobField(dataset.FieldByName('Img')).LoadFromStream(pic);
dataset.post;
pic.Free;
pjpg.free;
end;
/////////////////////////
procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
  DataCol: Integer; Column: TColumn; State: TGridDrawState);
begin
  if Column.FieldName = 'Res' then
  begin
    DBGrid1.Canvas.TextRect(Rect, Rect.Left, Rect.Top, Column.Field.AsString);
  end;
end;
//////////////////////////
从前辈的来的代码，请各位解释一下，谢谢

Answer 1

创建一个JPEG图片类和一个内存流,再把图片存入流中.
然后读进数据集.