TMemo and unicode

[ewong 3]

Hi,

I'm using Delphi 10.3.3 and I have two Memo fields on a form and a button.   I copy and paste a RFC2047 utf8 text to the left memo field.  Then I press the button, and the resulting unicode text should be on the right memo field; but I get gibberish. 

 

procedure TForm1.convertbuttonclick(Sender: TObject);
var
  use_st,
  s, s2 : string;
  b, q : boolean;

begin
  s := Memo1.lines[0];
  use_st := '?=';
  if pos('=?utf-8?', lowercase(s)) > 0 then
  begin
    s2 := stringreplace(s, '=?utf-8?', '', [rfReplaceAll, rfIgnoreCase]);
    if pos('b?', lowercase(s2)) > 0 then
    begin
      s2 := stringreplace(s2, 'b?', '', [rfReplaceAll, rfIgnoreCase]);
      b := True;
      use_st := '=?=';
    end
    else if pos('q?', lowercase(s2)) > 0 then
    begin
      s2 := stringreplace(s2, 'q?', '', [rfReplaceAll, rfIgnoreCase]);
      q := True;
    end;
  end
  else
    s2 := s;

  if pos(use_st, s2) > 0 then
    s2 := stringreplace(s2, use_st, '', [rfReplaceAll, rfIgnoreCase]);

  if q then
    s3 := idDecoderQuotedPrintable1.decodestring(s2)
  else if b then
    s3 := idDecoderMime1.decodeString(s2)
  else
    s3 := s2;

  memo2.lines.clear;
  memo2.lines.add(s3);
end;

 

Say I copy and paste "=?UTF-8?B?5aaC5L2V6K6TIGFydC1tYXRlIOaIkOeCug==?="  to the first memo.  I press the button, and I get

some string of which only I see "art-mate'.  

 

Can someone point out what I'm missing?

 

Thanks

 

Ed

 

 

 

 

[Lajos Juhász 295]

This question has nothing to do with VCL and Memo. You should ask it in Delphi Third-Party -> Indy as you're using Indy to decode the data.

 

Most probably your data is mailformed (I've tried to decode it using https://www.base64encode.org/ and the result there is: 如何讓 art-mate 成為) . 

 

In order to decode UTF-8 characters you have to add idGlobal to the uses and call DecodeString:

s3 := idDecoderMime1.decodeString(s2, IndyTextEncoding_UTF8)

 

[Remy Lebeau 1436]

The code shown is not the correct logic to parse an RFC2047-encoded string.  Try something more like the instead (though this could be simplified using IdGlobal.Fetch(), for instance):

uses
  IdGlobal, IdGobalProtocols, IdCoderMIME, idCoderQuotedPrintable;

procedure TForm1.convertbuttonclick(Sender: TObject);
var
  s, s2, charset, encoding, data : string;
  i, j: Integer;
begin
  s := Memo1.Lines[0];
  s2 := s;

  i := Pos('=?', s);
  if i > 0 then
  begin
    Inc(i, 2);
    j := Pos('?', s, i);
    if j > 0 then
    begin
      charset := Copy(s, i, j-i);
      i := j+1;
      j := Pos('?', s, i);
      if j > 0 then
      begin
        encoding := Copy(s, i, j-i);
        i := j + 1;
        j := Pos('?=', s, i);
        if j > 0 then
        begin
          data := Copy(s, i, j-i);
          if TextIsSame(encoding, 'B') then
            s2 := idDecoderMIME.DecodeString(data, CharsetToEncoding(charset))
          else if TextIsSame(encoding, 'Q') then
            s2 := idDecoderQuotedPrintable1.DecodeString(data, CharsetToEncoding(charset));
        end;
      end;
    end;
  end;

  Memo2.Lines.Clear;
  Memo2.Lines.Add(s2);
end;

That being said, Indy already implements a decoder for RFC2047-encoded strings, in the DecodeHeader() function of the IdCoderHeader unit, eg:

uses
  IdCoderHeader;

procedure TForm1.convertbuttonclick(Sender: TObject);
var
  s, s2 : string;
begin
  s := Memo1.Lines[0]; // '=?UTF-8?B?5aaC5L2V6K6TIGFydC1tYXRlIOaIkOeCug==?='
  s2 := DecodeHeader(s);
  Memo2.Text := s2;
end;

 

Edited March 24, 2021 by Remy Lebeau

[Lajos Juhász 295]

3 minutes ago, Remy Lebeau said:

TIdDecoderMIME is implemented in the IdCoderMIME unit, not in the IdGlobal unit.

IdGlobal is required for the function IndyTextEncoding_UTF8. 

[ewong 3]

9 hours ago, Remy Lebeau said:

That being said, Indy already implements a decoder for RFC2047-encoded strings, in the DecodeHeader() function of the IdCoderHeader unit, eg:
 

uses
  IdCoderHeader;

procedure TForm1.convertbuttonclick(Sender: TObject);
var
  s, s2 : string;
begin
  s := Memo1.Lines[0]; // '=?UTF-8?B?5aaC5L2V6K6TIGFydC1tYXRlIOaIkOeCug==?='
  s2 := DecodeHeader(s);
  Memo2.Text := s2;
end;

 

Hi Remy!

 

That's both short and sweet!  This is much better than the code I had. 

 

Edmund