Title: get notified when a CD is removed or inserted?
{
Some applications need to know when the user inserts or
removes a compact disc or DVD from a CD-ROM drive without
polling for media changes. Windows provide a way to notify these
applications through the WM_DEVICECHANGE message.
}
type
TForm1 = class(TForm)
private
procedure WMDeviceChange(var Msg: TMessage); message WM_DEVICECHANGE;
public
end;
{...}
implementation
{$R *.DFM}
procedure TForm1.WMDeviceChange(var Msg: TMessage);
const
DBT_DEVICEARRIVAL = $8000; // system detected a new device
DBT_DEVICEREMOVECOMPLETE = $8004; // device is gone
var
myMsg: string;
begin
inherited;
case Msg.wParam of
DBT_DEVICEARRIVAL: myMsg := 'CD inserted!';
DBT_DEVICEREMOVECOMPLETE: myMsg := 'CD removed!';
end;
ShowMessage(myMsg);
end;
{*********************************************}
// Advanced Code:
// When the device is of type volume, then we can get some device specific
// information, namely specific information about a logical volume.
// by Juergen Kantz
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
label1: TLabel;
private
procedure WMDeviceChange(var Msg: TMessage); message WM_DeviceChange;
{ Private declarations }
public
{ Public declarations }
end;
const
DBT_DeviceArrival = $8000;
DBT_DeviceRemoveComplete = $8004;
DBTF_Media = $0001;
DBT_DevTyp_Volume = $0002;
type
PDevBroadcastHdr = ^TDevBroadcastHdr;
TDevBroadcastHdr = packed record
dbcd_size: DWORD;
dbcd_devicetype: DWORD;
dbcd_reserved: DWORD;
end;
type
PDevBroadcastVolume = ^TDevBroadcastVolume;
TDevBroadcastVolume = packed record
dbcv_size: DWORD;
dbcv_devicetype: DWORD;
dbcv_reserved: DWORD;
dbcv_unitmask: DWORD;
dbcv_flags: Word;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
function GetDrive(pDBVol: PDevBroadcastVolume): string;
var
i: Byte;
Maske: DWORD;
begin
if (pDBVol^.dbcv_flags and DBTF_Media) = DBTF_Media then
begin
Maske := pDBVol^.dbcv_unitmask;
for i := 0 to 25 do
begin
if (Maske and 1) = 1 then
Result := Char(i + Ord('A')) + ':';
Maske := Maske shr 1;
end;
end;
end;
procedure TForm1.WMDeviceChange(var Msg: TMessage);
var
Drive: string;
begin
case Msg.wParam of
DBT_DeviceArrival:
if PDevBroadcastHdr(Msg.lParam)^.dbcd_devicetype = DBT_DevTyp_Volume then
begin
Drive := GetDrive(PDevBroadcastVolume(Msg.lParam));
label1.Caption := 'CD inserted in Drive ' + Drive;
end;
DBT_DeviceRemoveComplete:
if PDevBroadcastHdr(Msg.lParam)^.dbcd_devicetype = DBT_DevTyp_Volume then
begin
Drive := GetDrive(PDevBroadcastVolume(Msg.lParam));
label1.Caption := 'CD removed from Drive ' + Drive;
end;
end;
end;
end.