unit MapGForm;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, SyncObjs, TeEngine, Series, ExtCtrls, TeeProcs, Chart, Grids,
  ComCtrls;

type
  TForm1 = class(TForm)
    StringGrid1: TStringGrid;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure StringGrid1SelectCell(Sender: TObject; Col, Row: Integer;
      var CanSelect: Boolean);
  private
    hMapFile: THandle;
    MapFilePointer: Pointer;
  public
    procedure WmUser(var Msg: TMessage); message wm_user;
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.FormCreate(Sender: TObject);
var
  Address: Pointer;
begin
  hMapFile := CreateFileMapping(
    $FFFFFFFF, // file handle ... or memory
    nil, // security
    Page_ReadWrite, // access rights
    0, // high memory size
    10000, // low memory size
    'DdhMappedFileGraph'); // mapped file name
  if hMapFile <> 0 then
    MapFilePointer := MapViewOfFile(
      hMapFile, // handle returned above
      File_Map_All_Access, // access rights
      0, 0, 0) // access the entire mapped file
  else
    ShowMessage('hMapFile = 0');
  if MapFilePointer = nil then
    ShowMessage('MapFilePointer = nil')
  else
  begin
    // add window to area
    Address := pChar(MapFilePointer) + 400;
    while PInteger(Address)^ <> 0 do
      Address := pChar(Address) + 4;
    PInteger(Address)^ := Handle;
  end;
  // posts an update request to itself
  PostMessage(Handle, wm_user, 0, 0);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  UnMapViewOfFile(MapFilePointer);
  CloseHandle(hMapFile);
end;

procedure TForm1.WmUser(var Msg: TMessage);
var
  X, Y: Integer;
  Address: Pointer;
begin
  // update the grid
  for X := 0 to 9 do
    for Y := 0 to 9 do
    begin
      Address := pChar(MapFilePointer)
        + (X + Y * 10) * 4;
      StringGrid1.Cells[X, Y] :=
        IntToStr(PInteger(Address)^);
    end;
end;

procedure TForm1.StringGrid1SelectCell(Sender: TObject;
  Col, Row: Integer; var CanSelect: Boolean);
var
  Address: Pointer;
begin
  // reset the cell to 0
  Address := pChar(MapFilePointer) + (Col + Row * 10) * 4;
  PInteger(Address)^ := 0;
  // notify all listeners
  Address := pChar(MapFilePointer) + 400;
  while PInteger(Address)^ <> 0 do
  begin
    PostMessage(PInteger(Address)^, wm_user, 0, 0);
    Address := pChar(Address) + 4;
  end;
end;

end.