unit U_Usb;
interface
uses
 Windows, Messages, SysUtils, Classes, Forms;
type
 PDevBroadcastHdr = ^DEV_BROADCAST_HDR;
 DEV_BROADCAST_HDR = packed record
  dbch_size: DWORD;
  dbch_devicetype: DWORD;
  dbch_reserved: DWORD;
 end;
 PDevBroadcastDeviceInterface = ^DEV_BROADCAST_DEVICEINTERFACE;
 DEV_BROADCAST_DEVICEINTERFACE = record
  dbcc_size: DWORD;
  dbcc_devicetype: DWORD;
  dbcc_reserved: DWORD;
  dbcc_classguid: TGUID;
  dbcc_name: short;
 end;
const
 GUID_DEVINTERFACE_USB_DEVICE: TGUID = '{A5DCBF10-6530-11D2-901F-00C04FB951ED}';
 DBT_DEVICEARRIVAL = $8000; // system detected a new device
 DBT_DEVICEREMOVECOMPLETE = $8004; // device is gone
 DBT_DEVTYP_DEVICEINTERFACE = $00000005; // device interface class
type
 TComponentUSB = class(TComponent)
 private
  FWindowHandle: HWND;
  FOnUSBArrival: TNotifyEvent;
  FOnUSBRemove: TNotifyEvent;
  procedure WndProc(var Msg: TMessage);
  function USBRegister: Boolean;
 protected
  procedure WMDeviceChange(var Msg: TMessage); dynamic;
 public
  constructor Create(AOwner: TComponent); override;
  destructor Destroy; override;
 published
  property OnUSBArrival: TNotifyEvent read FOnUSBArrival write FOnUSBArrival;
  property OnUSBRemove: TNotifyEvent read FOnUSBRemove write FOnUSBRemove;
 end;
implementation
constructor TComponentUSB.Create(AOwner: TComponent);
begin
 inherited Create(AOwner);
 FWindowHandle := AllocateHWnd(WndProc);
 USBRegister;
end;
destructor TComponentUSB.Destroy;
begin
 DeallocateHWnd(FWindowHandle);
 inherited Destroy;
end;
procedure TComponentUSB.WndProc(var Msg: TMessage);
begin
 if (Msg.Msg = WM_DEVICECHANGE) then
 begin
  try
  WMDeviceChange(Msg);
  except
  Application.HandleException(Self);
  end;
 end
 else
  Msg.Result := DefWindowProc(FWindowHandle, Msg.Msg, Msg.wParam, Msg.lParam);
end;
procedure TComponentUSB.WMDeviceChange(var Msg: TMessage);
var
 devType: Integer;
 Datos: PDevBroadcastHdr;
begin
 if (Msg.wParam = DBT_DEVICEARRIVAL) or (Msg.wParam = DBT_DEVICEREMOVECOMPLETE) then
 begin
  Datos := PDevBroadcastHdr(Msg.lParam);
  devType := Datos^.dbch_devicetype;
  if devType = DBT_DEVTYP_DEVICEINTERFACE then
  begin // USB Device
  if Msg.wParam = DBT_DEVICEARRIVAL then
  begin
  if Assigned(FOnUSBArrival) then
  FOnUSBArrival(Self);
  end
  else
  begin
  if Assigned(FOnUSBRemove) then
  FOnUSBRemove(Self);
  end;
  end;
 end;
end;
function TComponentUSB.USBRegister: Boolean;
var
 dbi: DEV_BROADCAST_DEVICEINTERFACE;
 Size: Integer;
 r: Pointer;
begin
 Result := False;
 Size := SizeOf(DEV_BROADCAST_DEVICEINTERFACE);
 ZeroMemory(@dbi, Size);
 dbi.dbcc_size := Size;
 dbi.dbcc_devicetype := DBT_DEVTYP_DEVICEINTERFACE;
 dbi.dbcc_reserved := 0;
 dbi.dbcc_classguid := GUID_DEVINTERFACE_USB_DEVICE;
 dbi.dbcc_name := 0;
 r := RegisterDeviceNotification(FWindowHandle, @dbi,
  DEVICE_NOTIFY_WINDOW_HANDLE
  );
 if Assigned(r) then Result := True;
end;
end.