procedure TForm1.Button1Click(Sender: TObject);
var
  b : tbitmap;
  fr: TFormatRange;
  r : TRect;
begin
  b:=tbitmap.create;
  b.width:=rxrichedit1.width;
  b.height:=rxrichedit1.height;
  r:=rect(0,0,RXRichEdit1.Width*screen.Pixelsperinch,
    RXRichEdit1.Height*screen.Pixelsperinch);
  fr.hdc:=b.Canvas.handle;
  fr.hdctarget:=b.Canvas.handle;
  fr.rc:=r;
  fr.rcpage:=r;
  fr.chrg.cpMin:=0;
  fr.chrg.cpMax:=-1;
  Sendmessage(RXRichEdit1.handle,EM_FORMATRANGE,1,longint(@fr));
  image1.Picture.assign(b);
  b.free;
end;