Question

I have a problem with using streams. I would like to read my html code line by line. With reading file line by line i have no problems but i need to read actualy opened document with webbrowser so i write this:

procedure TForm2.SpeedButton2Click(Sender: TObject);
var
    iall : IHTMLElement;
    strumien : TStringStream;
    reader : TStreamReader;
begin
  if Assigned(WebBrowser1.Document) then
    begin
      iall := (WebBrowser1.Document AS IHTMLDocument2).body;
      while iall.parentElement <> nil do
        begin
          iall := iall.parentElement;
        end;
      Strumien:=Tstringstream.Create(iall.innerHTML);
      Strumien.Position:=0;
      reader:=TStreamReader.Create(Strumien, TEncoding.UTF8);
      reader.OwnStream;
      while not reader.EndOfStream do
        memo1.Lines.Add(reader.ReadLine);
    end;
end;

This code doesnt work. Reads only few lines from center of document and gives “List index out of bounds” Anyone know why? Using Embarcadero XE2 Delphi

Thanks a lot!

Answer 1

You are mixing different string encodings together, which might account for why TStreamReader is not able to read everything correctly. TStringStream also uses TEncoding in D2009+, but you are not specifying any TEncoding type in the TStringStream constructor, so it will use TEncoding.Default, which is not the same encoding as TEncoding.UTF8. So you are taking the original UTF-16 encoded HTML string, converting it to the OS default Ansi encoding, and then trying to read it back as UTF-8. That can only work if the data does not contain any non-ASCII characters in it.

Try this instead:

procedure TForm2.SpeedButton2Click(Sender: TObject);   
var   
  iall : IHTMLElement;   
  iparent : IHTMLElement;   
  strumien : TStringStream;   
  reader : TStreamReader;   
  s: String;
begin   
  if Assigned(WebBrowser1.Document) then   
  begin   
    iall := (WebBrowser1.Document AS IHTMLDocument2).body;   
    iparent := iall.parentElement;
    while iparent <> nil do
    begin
      iall := iparent;
      iparent := iparent.parentElement;   
    end;
    Strumien := TStringStream.Create(iall.innerHTML, TEncoding.UTF8, False);   
    try
      Strumien.Position := 0;
      reader := TStreamReader.Create(Strumien, TEncoding.UTF8);   
      try
        while not reader.EndOfStream do   
        begin
          s := reader.ReadLine;
          // use s as needed...
        end; 
      finally
        reader.Free;
      end;
    finally
      Strumien.Free;
    end;
  end;   
end;   

In the specific case of loading the document into a TMemo, you don’t need the TStringStream or TStreamReader at all:

procedure TForm2.SpeedButton2Click(Sender: TObject);   
var   
  iall : IHTMLElement;   
  iparent : IHTMLElement;   
begin   
  if Assigned(WebBrowser1.Document) then   
  begin   
    iall := (WebBrowser1.Document AS IHTMLDocument2).body;   
    iparent := iall.parentElement;
    while iparent <> nil do
    begin
      iall := iparent;
      iparent := iparent.parentElement;   
    end;
    Memo1.Text := iall.innerHTML;   
  end;   
end;