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apiwinapisendmessagememo

Append text to memo using Win API

I'm trying to append text lines with this code

SendMessage(Form1.log.Handle, WM_SETTEXT, 0, Integer(PChar(textLog)));

// textLog are some lines eg 'Program started at xxx' etc

but it doesnt append, just set new text

Solution

  • Found complete solution

        procedure appendLog(const S: string);
var
  SelStart, LineLen: Integer;
  Line: string;
begin

  SelStart := SendMessage(Form1.log.Handle, EM_LINEINDEX, 0, 0);
  if SelStart >= 0 then Line := S + #13#10 else
    begin
      SelStart := SendMessage(Form1.log.Handle, EM_LINEINDEX, -1, 0);
      if SelStart < 0 then Exit;
      LineLen := SendMessage(Form1.log.Handle, EM_LINELENGTH, SelStart, 0);
      if LineLen = 0 then Exit;
      Inc(SelStart, LineLen);
      Line := #13#10 + s;
    end;

  SendMessage(Form1.log.Handle, EM_SETSEL, SelStart, SelStart);
  SendMessage(Form1.log.Handle, EM_REPLACESEL, 0, Longint(PChar(Line)));

end;