Создание карты города

Graphics::TBitmap*b=new Graphics::TBitmap();
int h1,w1,p1,p2;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormCreate(TObject *Sender)
{
b->LoadFromFile("C:\\3.bmp");
h1=b->Height;
w1=b->Width;
Form1->ScrollBar1->Max=w1;
Form1->ScrollBar2->Max=h1;
Form1->ScrollBar1->PageSize=w1;
Form1->ScrollBar2->PageSize=h1;
Image1->Canvas->CopyMode=cmSrcCopy;
Image1->Canvas->CopyRect(Rect(0,0,500,500),b->Canvas,Rect(p1,p2,p1+Form1->ScrollBar1->PageSize,p2+Form1->ScrollBar2->PageSize));
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormDestroy(TObject *Sender)
{
delete b;        
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormMouseWheelDown(TObject *Sender,
      TShiftState Shift, TPoint &MousePos, bool &Handled)
{
Form1->ScrollBar1->PageSize=Form1->ScrollBar1->PageSize+10;
Form1->ScrollBar2->PageSize=Form1->ScrollBar2->PageSize+10;
Image1->Canvas->CopyRect(Rect(0,0,500,500),b->Canvas,Rect(p1,p2,p1+Form1->ScrollBar1->PageSize,p2+Form1->ScrollBar2->PageSize));
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormMouseWheelUp(TObject *Sender,
      TShiftState Shift, TPoint &MousePos, bool &Handled)
{
Form1->ScrollBar1->PageSize=Form1->ScrollBar1->PageSize-10;
Form1->ScrollBar2->PageSize=Form1->ScrollBar2->PageSize-10;
Image1->Canvas->CopyRect(Rect(0,0,500,500),b->Canvas,Rect(p1,p2,p1+Form1->ScrollBar1->PageSize,p2+Form1->ScrollBar2->PageSize));
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ScrollBar1Scroll(TObject *Sender,
      TScrollCode ScrollCode, int &ScrollPos)
{
p1=ScrollBar1->Position;
Image1->Canvas->CopyRect(Rect(0,0,500,500),b->Canvas,Rect(p1,p2,p1+Form1->ScrollBar1->PageSize,p2+Form1->ScrollBar2->PageSize));
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ScrollBar2Scroll(TObject *Sender,
      TScrollCode ScrollCode, int &ScrollPos)
{
p2=ScrollBar2->Position;
Image1->Canvas->CopyRect(Rect(0,0,500,500),b->Canvas,Rect(p1,p2,p1+Form1->ScrollBar1->PageSize,p2+Form1->ScrollBar2->PageSize));
}
//---------------------------------------------------------------------------