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DeviceNotifier.pas：源码内容
							{-----------------------------------------------------------------------------
 Unit Name: DeviceNotifier
 Author:    Paul Fisher / Andrew Semack
 Purpose:   Class for hot plug cd / dvd (usb etc)
 History:
-----------------------------------------------------------------------------}
{$WARN SYMBOL_DEPRECATED OFF}
unit DeviceNotifier;
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
  TDeviceNotifier = class(TComponent)
  private
    FWindowHandle: HWND;
    FOnUSBArrival: TNotifyEvent;
    FOnUSBRemove: TNotifyEvent;
    FHandle: pointer;
    procedure WndProc(var Msg: TMessage);
    function USBRegister: Boolean;
    function USBUnRegister: 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 TDeviceNotifier.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FHandle := nil;
  FWindowHandle := AllocateHWnd(WndProc);
  USBRegister;
end;
destructor TDeviceNotifier.Destroy;
begin
  USBUnRegister;
  DeallocateHWnd(FWindowHandle);
  inherited Destroy;
end;
procedure TDeviceNotifier.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 TDeviceNotifier.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
      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 TDeviceNotifier.USBRegister: Boolean;
var
  dbi: DEV_BROADCAST_DEVICEINTERFACE;
  Size: Integer;
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;
  FHandle := RegisterDeviceNotification(FWindowHandle, @dbi,
    DEVICE_NOTIFY_WINDOW_HANDLE);
  if Assigned(FHandle) then
    Result := True;
end;
function TDeviceNotifier.USBUnRegister: boolean;
begin
  if assigned(FHandle) then
    Result := UnRegisterDeviceNotification(FHandle)
  else
    Result := False;
end;
end.

						