问题
I am trying to understand the documentation at MSDN regarding Device Events and how to trigger a notification whenever a volume has been mounted.
I have managed to do this for USB devices using information presented in the following post: detect usb drive/device using delphi
as well as other information found on the internet, but I have noticed that it would be easier to detect when a volume has been mounted directly.
So my question is: how do I implement Device Events handling in my Delphi app?
I am looking at the following documentation: https://msdn.microsoft.com/en-us/library/windows/desktop/aa363217(v=vs.85).aspx
But I can't really figure out how to get it up and running.
So far I have tried the following code, which compiles properly, but nothing happens, please push me in the right direction:
PDevBroadcastHdr = ^DEV_BROADCAST_HDR;
DEV_BROADCAST_HDR = packed record
dbch_size : DWORD;
dbch_devicetype : DWORD;
dbch_reserved : DWORD;
end;
PDevBroadcastHandle = ^DEV_BROADCAST_HANDLE;
DEV_BROADCAST_HANDLE = packed record
dbch_size : DWORD ;
dbch_devicetype : DWORD ;
dbch_reserved : DWORD ;
dbch_handle : THandle ;
dbch_hdevnotify : HDEVNOTIFY ;
dbch_eventguid : TGUID ;
dbch_nameoffset : LongInt ;
dbch_data : byte ;
end;
...
procedure WMDeviceChange(var Msg: TMessage);
const
DBT_DEVTYP_HANDLE = $0006;
GUID_IO_VOLUME_MOUNT: TGUID = '{B5804878-1A96-11D2-8FFD-00A0C9A06D32}';
...
function TForm1.RegisterThis: Boolean;
var
dbv: DEV_BROADCAST_HANDLE;
Size: Integer;
r: Pointer;
begin
Size := SizeOf(DEV_BROADCAST_HANDLE);
ZeroMemory(@dbv, Size);
dbv.dbch_size := Size;
dbv.dbch_devicetype := DBT_DEVTYP_HANDLE;
dbv.dbch_reserved := 0;
dbv.dbch_handle := 0;
dbv.dbch_hdevnotify := nil;
dbv.dbch_eventguid := GUID_IO_VOLUME_MOUNT;
dbv.dbch_nameoffset := 0;
dbv.dbch_data := 0;
r := RegisterDeviceNotification(FWindowHandle, @dbv, DEVICE_NOTIFY_WINDOW_HANDLE);
if Assigned(r) then Result := True;
end;
procedure TForm1.WMDeviceChange(var Msg: TMessage);
var
VData: PDevBroadcastHandle;
begin
ShowMessage('Hello!');
end;
回答1:
There are quite a lot of problems with what you have so far. Here is what I can see.
Incorrect recipient
You are passing a window handle to RegisterDeviceNotification. However, it's far from clear that your window handle implements a message handler for WM_DEVICECHANGE. I recommend using AllocateHWnd to obtain a window handle, and handle WM_DEVICECHANGE in the window procedure that you supply to AllocateHWnd.
Failure to call UnregisterDeviceNotification
The documentation of RegisterDeviceNotification says:
Device notification handles returned by RegisterDeviceNotification must be closed by calling the UnregisterDeviceNotification function when they are no longer needed.
You fail to do this. You have to hold on to the handle returned by RegisterDeviceNotification and pass it to UnregisterDeviceNotification when you no longer want to receive notifications.
Erroneous packing of records
You declared packed records. This is a mistake. For reasons unclear to me, it seems to be a prevailing mistake for Delphi developers to pack their records. Packing results in poor performance. Even worse, when performing interop with aligned records, packing simply results in an incorrect laying out of the record. These records are not packed.
Furthermore, I don't believe that your record should include a dbch_data member. That's only used for DBT_CUSTOMEVENT and I don't think that applies to you. I would declare the record like this:
type
DEV_BROADCAST_HANDLE = record
dbch_size : DWORD ;
dbch_devicetype : DWORD ;
dbch_reserved : DWORD ;
dbch_handle : THandle ;
dbch_hdevnotify : HDEVNOTIFY ;
dbch_eventguid : TGUID ;
dbch_nameoffset : LONG ;
end;
Weak error checking
You do check the return value of the call to RegisterDeviceNotification. That's good. But if that call fails then you don't call GetLastError to find out why, as described in the documentation. I'd write the call like this:
var
DevNotificationHandle: HDEVNOTIFY;
....
DevNotificationHandle := RegisterDeviceNotification(...);
Win32Check(DevNotificationHandle <> 0);
That way any errors will be translated into exceptions with textual error messages representing the Win32 error code.
Likely incorrect value of dbch_devicetype
I think you should be passing DBT_DEVTYP_DEVICEINTERFACE rather than DBT_DEVTYP_HANDLE. If you switch to DBT_DEVTYP_DEVICEINTERFACE and address all the points I raised above, then you will receive notifications. For instance:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Classes,
Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.StdCtrls;
type
TForm1 = class(TForm)
Memo1: TMemo;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FWindow: HWND;
FDevNotificationHandle: HDEVNOTIFY;
procedure WndMethod(var Message: TMessage);
function HandleDeviceChange(Event: DWORD; Data: Pointer): Boolean;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
type
DEV_BROADCAST_HANDLE = record
dbch_size: DWORD;
dbch_devicetype: DWORD;
dbch_reserved: DWORD;
dbch_handle: THandle;
dbch_hdevnotify: HDEVNOTIFY;
dbch_eventguid: TGUID;
dbch_nameoffset: LONG;
end;
const
DBT_DEVTYP_DEVICEINTERFACE = $0005;
GUID_IO_VOLUME_MOUNT: TGUID = '{B5804878-1A96-11D2-8FFD-00A0C9A06D32}';
procedure TForm1.FormCreate(Sender: TObject);
var
dbh: DEV_BROADCAST_HANDLE;
begin
FWindow := AllocateHWnd(WndMethod);
dbh := Default(DEV_BROADCAST_HANDLE);
dbh.dbch_size := SizeOf(dbh);
dbh.dbch_devicetype := DBT_DEVTYP_DEVICEINTERFACE;
dbh.dbch_eventguid := GUID_IO_VOLUME_MOUNT;
FDevNotificationHandle := RegisterDeviceNotification(FWindow, @dbh,
DEVICE_NOTIFY_WINDOW_HANDLE);
Win32Check(FDevNotificationHandle <> nil);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
if FDevNotificationHandle <> nil then
Win32Check(UnregisterDeviceNotification(FDevNotificationHandle));
DeallocateHWnd(FWindow);
end;
procedure TForm1.WndMethod(var Message: TMessage);
begin
case Message.Msg of
WM_DEVICECHANGE:
Message.Result := ord(HandleDeviceChange(Message.WParam,
Pointer(Message.LParam)));
else
Message.Result := DefWindowProc(FWindow, Message.Msg, Message.WParam,
Message.LParam);
end;
end;
function TForm1.HandleDeviceChange(Event: DWORD; Data: Pointer): Boolean;
begin
Memo1.Lines.Add(Format('%4x', [Event]));
Result := True;
end;
end.
Note that a default set of notifications is broadcast to top-level windows. So you may not even need to register because I believe that volume changes are part of the default set.
回答2:
You have to declare your WMDeviceChange method like this to receive message:
procedure WMDeviceChange(var Msg: TMessage); message WM_DEVICECHANGE;
Also, since your WMDeviceChange method is part of the Form you should use Form window Handle to register message.
r := RegisterDeviceNotification(Handle, @dbv, DEVICE_NOTIFY_WINDOW_HANDLE);
Since Handle can be recreated during Form's lifetime you should override Form's CreateWnd method and add registration there.
Or even better, you can encapsulate functionality in another class:
TDeviceDetector = class
protected
fHandle: THandle;
procedure WndProc(var Message: TMessage);
public
constructor Create;
destructor Destroy; override;
function RegisterThis: Boolean;
end;
constructor TDeviceDetector.Create;
begin
inherited;
fHandle := AllocateHWnd(WndProc);
end;
destructor TDeviceDetector.Destroy;
begin
DeallocateHWnd(fHandle);
inherited;
end;
function TDeviceDetector.RegisterThis: Boolean;
var
dbv: DEV_BROADCAST_HANDLE;
Size: Integer;
r: Pointer;
begin
Size := SizeOf(DEV_BROADCAST_HANDLE);
ZeroMemory(@dbv, Size);
dbv.dbch_size := Size;
dbv.dbch_devicetype := DBT_DEVTYP_HANDLE;
dbv.dbch_reserved := 0;
dbv.dbch_handle := 0;
dbv.dbch_hdevnotify := nil;
dbv.dbch_eventguid := GUID_IO_VOLUME_MOUNT;
dbv.dbch_nameoffset := 0;
dbv.dbch_data := 0;
r := RegisterDeviceNotification(fHandle, @dbv, DEVICE_NOTIFY_WINDOW_HANDLE);
if Assigned(r) then Result := True;
end;
procedure TDeviceDetector.WndProc(var Message: TMessage);
begin
if Message.Msg = WM_DEVICECHANGE then
begin
ShowMessage('Hello!');
end
else Message.Result := DefWindowProc(FHandle, Message.Msg, Message.wParam, Message.lParam); // Default Message Handler
end;
回答3:
EDIT: Found a component on a forum regarding this. It is called TSHChangeNotify and was written by Elliott Shevinm back in 2000 (!)
See the forum thread here. It contains the sourcecode and a fix. Theres also an article written by Zarko Gajic which explains how it works found here
It works perfectly fine in Delphi XE7 on Windows 8.1 when using VCL only.
UPDATE: I modified the code so it now runs on Delphi XE7 with Firemonkey. The updated code can be found here.
The way I set it up is by setting TSHChangeNotify.HardDriveOnly to FALSE
and putting TSHChangeNotify.Execute inside main forms OnCreate procedure.
Thanks to Dalija and David, I received some good information and code which came in handy.
However their answers did not solve my problem.
Like David said in one of the comments, he just wanted to "push me in the right direction" as I myself suggested in my question. Fair enough.
I started Googling for "guid_io_volume_mount c++" to see if I could find some usable code elsewhere that I could port.
I came across this forum post: http://www.mofeel.net/957-microsoft-public-vc-language/2343.aspx
The OP mentioned in his code that CreateFileA should be used in order to basically "monitor" whenever a mount point has changed.
A mount point seems to be the drive letter, for example C:, D:, E: etc...
So basically what happens is that by using the following code
var
dbv: DEV_BROADCAST_HANDLE;
Size: Integer;
r: Pointer;
begin
Size := SizeOf(DEV_BROADCAST_HANDLE);
ZeroMemory(@dbv, Size);
dbv.dbch_size := Size;
dbv.dbch_devicetype := DBT_DEVTYP_HANDLE;
dbv.dbch_reserved := 0;
dbv.dbch_handle := CreateFileA('\\.\C:', GENERIC_READ, FILE_SHARE_READ+FILE_SHARE_WRITE, nil, OPEN_EXISTING, FILE_FLAG_NO_BUFFERING + FILE_ATTRIBUTE_NORMAL + FILE_FLAG_SEQUENTIAL_SCAN, 0);
dbv.dbch_hdevnotify := 0;
dbv.dbch_nameoffset := 0;
r := RegisterDeviceNotification(fHandle, @dbv, DEVICE_NOTIFY_WINDOW_HANDLE);
if Assigned(r) then Result := True;
we let the OS know that whenever "C:" has changed its mount state (mount/dismount), the OS will send a message to our WndProc message catcher.
My full source is avaible below, still a bit buggy, but it presents a concept so far.
It can detect when a specified volume is mounted, at least. Dismount is detected when you right click on a volume and select "Eject".
Now remember, this code can do more than just detecting when mount points are changed, this MSDN article has all the GUID's you need to do some pretty neat stuff.
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Classes,
Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.StdCtrls, Vcl.dialogs;
type
TDeviceDetector = class
protected
fHandle: THandle;
fLogger: TMemo;
fOnCDROM_EXCLUSIVE_LOCK ,
fOnCDROM_EXCLUSIVE_UNLOCK ,
fOnDEVICE_BECOMING_READY ,
fOnDEVICE_EXTERNAL_REQUEST ,
fOnMEDIA_ARRIVAL ,
fOnMEDIA_EJECT_REQUEST ,
fOnMEDIA_REMOVAL ,
fOnVOLUME_CHANGE ,
fOnVOLUME_CHANGE_SIZE ,
fOnVOLUME_DISMOUNT ,
fOnVOLUME_DISMOUNT_FAILED ,
fOnVOLUME_FVE_STATUS_CHANGE ,
fOnVOLUME_LOCK ,
fOnVOLUME_LOCK_FAILED ,
fOnVOLUME_MOUNT ,
fOnVOLUME_NAME_CHANGE ,
fOnVOLUME_NEED_CHKDSK ,
fOnVOLUME_PHYSICAL_CONFIGURATION_CHANGE ,
fOnVOLUME_PREPARING_EJECT ,
fOnVOLUME_UNIQUE_ID_CHANGE ,
fOnVOLUME_UNLOCK ,
fOnVOLUME_WEARING_OUT : TNotifyEvent;
procedure WndProc(var Message: TMessage);
procedure Log(AStr: string);
public
constructor Create;
destructor Destroy; override;
function RegisterThis: Boolean;
property Logger: TMemo read fLogger write fLogger;
published
property OnCDROM_EXCLUSIVE_LOCK : TNotifyEvent read fOnCDROM_EXCLUSIVE_LOCK write fOnCDROM_EXCLUSIVE_LOCK ;
property OnCDROM_EXCLUSIVE_UNLOCK : TNotifyEvent read fOnCDROM_EXCLUSIVE_UNLOCK write fOnCDROM_EXCLUSIVE_UNLOCK ;
property OnDEVICE_BECOMING_READY : TNotifyEvent read fOnDEVICE_BECOMING_READY write fOnDEVICE_BECOMING_READY ;
property OnDEVICE_EXTERNAL_REQUEST : TNotifyEvent read fOnDEVICE_EXTERNAL_REQUEST write fOnDEVICE_EXTERNAL_REQUEST ;
property OnMEDIA_ARRIVAL : TNotifyEvent read fOnMEDIA_ARRIVAL write fOnMEDIA_ARRIVAL ;
property OnMEDIA_EJECT_REQUEST : TNotifyEvent read fOnMEDIA_EJECT_REQUEST write fOnMEDIA_EJECT_REQUEST ;
property OnMEDIA_REMOVAL : TNotifyEvent read fOnMEDIA_REMOVAL write fOnMEDIA_REMOVAL ;
property OnVOLUME_CHANGE : TNotifyEvent read fOnVOLUME_CHANGE write fOnVOLUME_CHANGE ;
property OnVOLUME_CHANGE_SIZE : TNotifyEvent read fOnVOLUME_CHANGE_SIZE write fOnVOLUME_CHANGE_SIZE ;
property OnVOLUME_DISMOUNT : TNotifyEvent read fOnVOLUME_DISMOUNT write fOnVOLUME_DISMOUNT ;
property OnVOLUME_DISMOUNT_FAILED : TNotifyEvent read fOnVOLUME_DISMOUNT_FAILED write fOnVOLUME_DISMOUNT_FAILED ;
property OnVOLUME_FVE_STATUS_CHANGE : TNotifyEvent read fOnVOLUME_FVE_STATUS_CHANGE write fOnVOLUME_FVE_STATUS_CHANGE ;
property OnVOLUME_LOCK : TNotifyEvent read fOnVOLUME_LOCK write fOnVOLUME_LOCK ;
property OnVOLUME_LOCK_FAILED : TNotifyEvent read fOnVOLUME_LOCK_FAILED write fOnVOLUME_LOCK_FAILED ;
property OnVOLUME_MOUNT : TNotifyEvent read fOnVOLUME_MOUNT write fOnVOLUME_MOUNT ;
property OnVOLUME_NAME_CHANGE : TNotifyEvent read fOnVOLUME_NAME_CHANGE write fOnVOLUME_NAME_CHANGE ;
property OnVOLUME_NEED_CHKDSK : TNotifyEvent read fOnVOLUME_NEED_CHKDSK write fOnVOLUME_NEED_CHKDSK ;
property OnVOLUME_PHYSICAL_CONFIGURATION_CHANGE : TNotifyEvent read fOnVOLUME_PHYSICAL_CONFIGURATION_CHANGE write fOnVOLUME_PHYSICAL_CONFIGURATION_CHANGE;
property OnVOLUME_PREPARING_EJECT : TNotifyEvent read fOnVOLUME_PREPARING_EJECT write fOnVOLUME_PREPARING_EJECT ;
property OnVOLUME_UNIQUE_ID_CHANGE : TNotifyEvent read fOnVOLUME_UNIQUE_ID_CHANGE write fOnVOLUME_UNIQUE_ID_CHANGE ;
property OnVOLUME_UNLOCK : TNotifyEvent read fOnVOLUME_UNLOCK write fOnVOLUME_UNLOCK ;
property OnVOLUME_WEARING_OUT : TNotifyEvent read fOnVOLUME_WEARING_OUT write fOnVOLUME_WEARING_OUT ;
end;
TForm1 = class(TForm)
Memo1: TMemo;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
end;
var
Form1: TForm1;
dd: TDeviceDetector;
implementation
{$R *.dfm}
type
PDevBroadcastHdr = ^DEV_BROADCAST_HDR;
DEV_BROADCAST_HDR = packed record
dbch_size : DWORD;
dbch_devicetype : DWORD;
dbch_reserved : DWORD;
end;
PDevBroadcastHandle = ^DEV_BROADCAST_HANDLE;
DEV_BROADCAST_HANDLE = record
dbch_size : DWORD;
dbch_devicetype : DWORD;
dbch_reserved : DWORD;
dbch_handle : THandle;
dbch_hdevnotify : HDEVNOTIFY;
dbch_eventguid : TGUID;
dbch_nameoffset : LONG;
dbch_data: array [0..0] of Byte;
end;
const
DEVICE_NOTIFY_ALL_INTERFACE_CLASSES = $00000004;
DBT_CUSTOMEVENT = $8006;
DBT_DEVTYP_HANDLE = $0006;
GUID_IO_CDROM_EXCLUSIVE_LOCK : TGUID = '{bc56c139-7a10-47ee-a294-4c6a38f0149a}';
GUID_IO_CDROM_EXCLUSIVE_UNLOCK : TGUID = '{a3b6d27d-5e35-4885-81e5-ee18c00ed779}';
GUID_IO_DEVICE_BECOMING_READY : TGUID = '{d07433f0-a98e-11d2-917a-00a0c9068ff3}';
GUID_IO_DEVICE_EXTERNAL_REQUEST : TGUID = '{d07433d0-a98e-11d2-917a-00a0c9068ff3}';
GUID_IO_MEDIA_ARRIVAL : TGUID = '{d07433c0-a98e-11d2-917a-00a0c9068ff3}';
GUID_IO_MEDIA_EJECT_REQUEST : TGUID = '{d07433d1-a98e-11d2-917a-00a0c9068ff3}';
GUID_IO_MEDIA_REMOVAL : TGUID = '{d07433c1-a98e-11d2-917a-00a0c9068ff3}';
GUID_IO_VOLUME_CHANGE : TGUID = '{7373654a-812a-11d0-bec7-08002be2092f}';
GUID_IO_VOLUME_CHANGE_SIZE : TGUID = '{3a1625be-ad03-49f1-8ef8-6bbac182d1fd}';
GUID_IO_VOLUME_DISMOUNT : TGUID = '{d16a55e8-1059-11d2-8ffd-00a0c9a06d32}';
GUID_IO_VOLUME_DISMOUNT_FAILED : TGUID = '{E3C5B178-105D-11D2-8FFD-00A0C9A06D32}';
GUID_IO_VOLUME_FVE_STATUS_CHANGE : TGUID = '{062998b2-ee1f-4b6a-b857-e76cbbe9a6da}';
GUID_IO_VOLUME_LOCK : TGUID = '{50708874-c9af-11d1-8fef-00a0c9a06d32}';
GUID_IO_VOLUME_LOCK_FAILED : TGUID = '{ae2eed10-0ba8-11d2-8ffb-00a0c9a06d32}';
GUID_IO_VOLUME_MOUNT : TGUID = '{b5804878-1a96-11d2-8ffd-00a0c9a06d32}';
GUID_IO_VOLUME_NAME_CHANGE : TGUID = '{2de97f83-4c06-11d2-a532-00609713055a}';
GUID_IO_VOLUME_NEED_CHKDSK : TGUID = '{799a0960-0a0b-4e03-ad88-2fa7c6ce748a}';
GUID_IO_VOLUME_PHYSICAL_CONFIGURATION_CHANGE : TGUID = '{2de97f84-4c06-11d2-a532-00609713055a}';
GUID_IO_VOLUME_PREPARING_EJECT : TGUID = '{c79eb16e-0dac-4e7a-a86c-b25ceeaa88f6}';
GUID_IO_VOLUME_UNIQUE_ID_CHANGE : TGUID = '{af39da42-6622-41f5-970b-139d092fa3d9}';
GUID_IO_VOLUME_UNLOCK : TGUID = '{9a8c3d68-d0cb-11d1-8fef-00a0c9a06d32}';
GUID_IO_VOLUME_WEARING_OUT : TGUID = '{873113ca-1486-4508-82ac-c3b2e5297aaa}';
function WDE_GUID_To_String(AGUID: TGUID): string; //WDE stands for Windows Device Events
begin
if AGUID = GUID_IO_CDROM_EXCLUSIVE_LOCK then result := 'GUID_IO_CDROM_EXCLUSIVE_LOCK' else
if AGUID = GUID_IO_CDROM_EXCLUSIVE_UNLOCK then result := 'GUID_IO_CDROM_EXCLUSIVE_UNLOCK' else
if AGUID = GUID_IO_DEVICE_BECOMING_READY then result := 'GUID_IO_DEVICE_BECOMING_READY' else
if AGUID = GUID_IO_DEVICE_EXTERNAL_REQUEST then result := 'GUID_IO_DEVICE_BECOMING_READY' else
if AGUID = GUID_IO_MEDIA_ARRIVAL then result := 'GUID_IO_MEDIA_ARRIVAL' else
if AGUID = GUID_IO_MEDIA_EJECT_REQUEST then result := 'GUID_IO_MEDIA_EJECT_REQUEST' else
if AGUID = GUID_IO_MEDIA_REMOVAL then result := 'GUID_IO_MEDIA_REMOVAL' else
if AGUID = GUID_IO_VOLUME_CHANGE then result := 'GUID_IO_VOLUME_CHANGE' else
if AGUID = GUID_IO_VOLUME_CHANGE_SIZE then result := 'GUID_IO_VOLUME_CHANGE_SIZE' else
if AGUID = GUID_IO_VOLUME_DISMOUNT then result := 'GUID_IO_VOLUME_DISMOUNT' else
if AGUID = GUID_IO_VOLUME_DISMOUNT_FAILED then result := 'GUID_IO_VOLUME_DISMOUNT_FAILED' else
if AGUID = GUID_IO_VOLUME_FVE_STATUS_CHANGE then result := 'GUID_IO_VOLUME_FVE_STATUS_CHANGE' else
if AGUID = GUID_IO_VOLUME_LOCK then result := 'GUID_IO_VOLUME_LOCK' else
if AGUID = GUID_IO_VOLUME_LOCK_FAILED then result := 'GUID_IO_VOLUME_LOCK_FAILED' else
if AGUID = GUID_IO_VOLUME_MOUNT then result := 'GUID_IO_VOLUME_MOUNT' else
if AGUID = GUID_IO_VOLUME_NAME_CHANGE then result := 'GUID_IO_VOLUME_NAME_CHANGE' else
if AGUID = GUID_IO_VOLUME_NEED_CHKDSK then result := 'GUID_IO_VOLUME_NEED_CHKDSK' else
if AGUID = GUID_IO_VOLUME_PHYSICAL_CONFIGURATION_CHANGE then result := 'GUID_IO_VOLUME_PHYSICAL_CONFIGURATION_CHANGE' else
if AGUID = GUID_IO_VOLUME_PREPARING_EJECT then result := 'GUID_IO_VOLUME_PREPARING_EJECT' else
if AGUID = GUID_IO_VOLUME_UNIQUE_ID_CHANGE then result := 'GUID_IO_VOLUME_UNIQUE_ID_CHANGE' else
if AGUID = GUID_IO_VOLUME_UNLOCK then result := 'GUID_IO_VOLUME_UNLOCK' else
if AGUID = GUID_IO_VOLUME_WEARING_OUT then result := 'GUID_IO_VOLUME_WEARING_OUT';
end;
constructor TDeviceDetector.Create;
begin
inherited;
fHandle := AllocateHWnd(WndProc);
end;
destructor TDeviceDetector.Destroy;
begin
DeallocateHWnd(fHandle);
inherited;
end;
function TDeviceDetector.RegisterThis: Boolean;
var
dbv: DEV_BROADCAST_HANDLE;
Size: Integer;
r: Pointer;
begin
Size := SizeOf(DEV_BROADCAST_HANDLE);
ZeroMemory(@dbv, Size);
dbv.dbch_size := Size;
dbv.dbch_devicetype := DBT_DEVTYP_HANDLE;
dbv.dbch_reserved := 0;
dbv.dbch_handle := CreateFileA('\\.\E:', GENERIC_READ, FILE_SHARE_READ + FILE_SHARE_WRITE, nil, OPEN_EXISTING, FILE_FLAG_NO_BUFFERING + FILE_ATTRIBUTE_NORMAL + FILE_FLAG_SEQUENTIAL_SCAN, 0);
dbv.dbch_hdevnotify := RegisterDeviceNotification(fHandle, @dbv, DEVICE_NOTIFY_ALL_INTERFACE_CLASSES);;
dbv.dbch_nameoffset := 0;
if Assigned(dbv.dbch_hdevnotify) then Result := True;
end;
procedure TDeviceDetector.WndProc(var Message: TMessage);
var data: PDevBroadcastHdr;
data_H: PDevBroadcastHandle;
begin
if Message.wParam = DBT_CUSTOMEVENT then //according to MSDN, DEV_BROADCAST_HANDLE structure is treated as a custom event.
begin
Data := PDevBroadcastHdr(Message.LParam); //we need to treat this custom evend a DEV_BROADCAST_HDR structure first...
if Data^.dbch_devicetype = DBT_DEVTYP_HANDLE then //then we check if the device type is DBT_DEVTYP_HANDLE
begin
data_H := PDevBroadcastHandle(Message.lParam); //if the device type is DBT_DEVTYP_HANDLE, we treat the custom event as a DEV_BROADCAST_HANDLE structure
//final step is to see what GUID the event of the structure DEV_BROADCAST_HANDLE has
Log(WDE_GUID_To_String(data_H^.dbch_eventguid));
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_CDROM_EXCLUSIVE_LOCK) = true then if assigned(fOnCDROM_EXCLUSIVE_LOCK) then fOnCDROM_EXCLUSIVE_LOCK(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_CDROM_EXCLUSIVE_UNLOCK) = true then if assigned(fOnCDROM_EXCLUSIVE_UNLOCK) then fOnCDROM_EXCLUSIVE_UNLOCK(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_DEVICE_BECOMING_READY) = true then if assigned(fOnDEVICE_BECOMING_READY) then fOnDEVICE_BECOMING_READY(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_DEVICE_EXTERNAL_REQUEST) = true then if assigned(fOnDEVICE_EXTERNAL_REQUEST) then fOnDEVICE_EXTERNAL_REQUEST(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_MEDIA_ARRIVAL) = true then if assigned(fOnMEDIA_ARRIVAL) then fOnMEDIA_ARRIVAL(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_MEDIA_EJECT_REQUEST) = true then if assigned(fOnMEDIA_EJECT_REQUEST) then fOnMEDIA_EJECT_REQUEST(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_MEDIA_REMOVAL) = true then if assigned(fOnMEDIA_REMOVAL) then fOnMEDIA_REMOVAL(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_CHANGE) = true then if assigned(fOnVOLUME_CHANGE) then fOnVOLUME_CHANGE(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_CHANGE_SIZE) = true then if assigned(fOnVOLUME_CHANGE_SIZE) then fOnVOLUME_CHANGE_SIZE(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_DISMOUNT) = true then if assigned(fOnVOLUME_DISMOUNT) then fOnVOLUME_DISMOUNT(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_DISMOUNT_FAILED) = true then if assigned(fOnVOLUME_DISMOUNT_FAILED) then fOnVOLUME_DISMOUNT_FAILED(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_FVE_STATUS_CHANGE) = true then if assigned(fOnVOLUME_FVE_STATUS_CHANGE) then fOnVOLUME_FVE_STATUS_CHANGE(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_LOCK) = true then if assigned(fOnVOLUME_LOCK) then fOnVOLUME_LOCK(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_LOCK_FAILED) = true then if assigned(fOnVOLUME_LOCK_FAILED) then fOnVOLUME_LOCK_FAILED(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_MOUNT) = true then if assigned(fOnVOLUME_MOUNT) then fOnVOLUME_MOUNT(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_NAME_CHANGE) = true then if assigned(fOnVOLUME_NAME_CHANGE) then fOnVOLUME_NAME_CHANGE(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_NEED_CHKDSK) = true then if assigned(fOnVOLUME_NEED_CHKDSK) then fOnVOLUME_NEED_CHKDSK(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_PHYSICAL_CONFIGURATION_CHANGE) = true then if assigned(fOnVOLUME_PHYSICAL_CONFIGURATION_CHANGE) then fOnVOLUME_PHYSICAL_CONFIGURATION_CHANGE(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_PREPARING_EJECT) = true then if assigned(fOnVOLUME_PREPARING_EJECT) then fOnVOLUME_PREPARING_EJECT(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_UNIQUE_ID_CHANGE) = true then if assigned(fOnVOLUME_UNIQUE_ID_CHANGE) then fOnVOLUME_UNIQUE_ID_CHANGE(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_UNLOCK) = true then if assigned(fOnVOLUME_UNLOCK) then fOnVOLUME_UNLOCK(self) else
if IsEqualGUID(data_H^.dbch_eventguid, GUID_IO_VOLUME_WEARING_OUT) = true then if assigned(fOnVOLUME_WEARING_OUT) then fOnVOLUME_WEARING_OUT(self);
end;
end;
end;
procedure TDeviceDetector.Log(AStr: string);
begin
fLogger.Lines.Add(AStr);
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
dd := TDeviceDetector.Create;
dd.Logger := Memo1;
if dd.RegisterThis = true then Memo1.Lines.Add('Registered!') else Memo1.Lines.Add('Failed to register!');
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
dd.free;
end;
end.
来源：https://stackoverflow.com/questions/28927683/detecting-when-a-volume-is-mounted-in-windows-with-delphi