Code:

uses

  RichEdit;

// Using the Paragraph property

procedure RE_AlignText1(ARichEdit: TRichEdit; alignment: TAlignment);

begin

  ARichEdit.Paragraph.Alignment := alignment;

end;

// Using PARAFORMAT2; nonVCL

procedure RE_AlignText2(ARichEdit: TRichEdit; alignment: TAlignment);

var

  pf2: PARAFORMAT2;

begin

  FillChar(pf2, SizeOf(pf2), 0);

  pf2.cbSize := SizeOf(PARAFORMAT2);

  SendMessage(ARichEdit.Handle, EM_GETPARAFORMAT, 0, Longint(@pf2));

  pf2.dwMask := PFM_ALIGNMENT;

  case alignment of

    taLeftJustify: pf2.wAlignment := PFA_LEFT;

    taCenter: pf2.wAlignment := PFA_CENTER;

    taRightJustify: pf2.wAlignment := PFA_RIGHT;

  end;

  SendMessage(ARichEdit.Handle, EM_SETPARAFORMAT, 0, Longint(@pf2));

end;

// Example: Right align text

// Beispiel: Text rechtsbundig ausrichten

procedure TForm1.Button1Click(Sender: TObject);

begin

  RE_AlignText2(RichEdit1, taRightJustify);

end;