void __fastcall TForm1::FormCreate(TObject *Sender)
{
  pl=new TList();
  btn_pressed=false;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormDestroy(TObject *Sender)
{
  for(int i=0;i<pl->Count;i++){
    delete pl->Items[i];
  }
  delete pl;
}
//---------------------------------------------------------------------------

void __fastcall TForm1::PaintBox1MouseDown(TObject *Sender,
      TMouseButton Button, TShiftState Shift, int X, int Y)
{
  btn_pressed=true;
  pl->Add(new TPoint(-1,0));
  pl->Add(new TPoint(X,Y));
  PaintBox1->Canvas->MoveTo(X,Y);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::PaintBox1MouseUp(TObject *Sender,
      TMouseButton Button, TShiftState Shift, int X, int Y)
{
  btn_pressed=false;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::PaintBox1MouseMove(TObject *Sender,
      TShiftState Shift, int X, int Y)
{
  if(btn_pressed){
    PaintBox1->Canvas->LineTo(X,Y);
    pl->Add(new TPoint(X,Y));
  }
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender) //clear
{
  PaintBox1->Canvas->FillRect(PaintBox1->ClientRect);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender) // re-draw
{
  for(int i=0;i<pl->Count;i++){
    if(((TPoint*)(pl->Items[i]))->x==-1){
      i++;
      PaintBox1->Canvas->MoveTo(((TPoint*)(pl->Items[i]))->x,((TPoint*)(pl->Items[i]))->y);
    }else{
      PaintBox1->Canvas->LineTo(((TPoint*)(pl->Items[i]))->x,((TPoint*)(pl->Items[i]))->y);
    }
  }
}
.끝.

조성택 님이 쓰신 글 :
: 페인트 박스에서 마우스로 선을 그리고 다시 그려질대는 TList에 미리 정보를 넣어서 다시 그리게 하려고 하는데 잘 안되네요..하는 방법좀..