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Frequently Asked Questions

Testing/setting the CD autorun option under Win32

Question:

How can I test and set the CD autorun option under 32 bit versions of Windows?

Answer:

You can check the 4 byte value in the Windows registry under:

Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\
NoDriveTypeAutoRun

Setting the following bit numbers of the value of this key will 
cause Windows not to use any auto run capabilities that may be 
present for the device denoted by the bit number.

DRIVE_UNKNOWN = bit # 0
DRIVE_NO_ROOT_DIR = bit #1
DRIVE_REMOVABLE= Bit # 2
DRIVE_FIXED = Bit #3
DRIVE_REMOTE= Bit #4
DRIVE_CDROM= Bit #5
DRIVE_RAMDISK= Bit #6

You can also set this value to test the autorun capability of a
program you are developing from a floppy or network drive, by 
setting the value to boot the autorun program from a floppy disk
(DRIVE_REMOVEABLE) or network drive (DRIVE_REMOTE). If the 
device does not have auto-insert detection capabilities, simply 
inserting the disk and pressing F-5 from the Windows explorer 
should cause the autorun program to boot.

The following example demonstrates the ability to check if the 
autorun detection of the CD is enabled, and also demonstrates 
the ability of turning the autorun detection both on and off 
for the CD.

Example

uses
  Registry;

function IsCdAutoRunOn : bool;
var
  reg: TRegistry;
  AutoRunSetting : integer;
begin
  reg := TRegistry.Create;
  reg.RootKey := HKEY_CURRENT_USER;
  reg.OpenKey(
    'Software\Microsoft\Windows\CurrentVersion\Policies\Explorer',
              false);
  reg.ReadBinaryData('NoDriveTypeAutoRun',
                     AutoRunSetting ,
                     sizeof(AutoRunSetting));
  reg.CloseKey;
  reg.free;
  result :=  not ((AutoRunSetting and (1 shl 5)) <> 0);
end;

procedure SetCdAutoRun(bOn : bool);
var
  reg: TRegistry;
  AutoRunSetting : integer;
begin
  reg := TRegistry.Create;
  reg.RootKey := HKEY_CURRENT_USER;
  reg.LazyWrite := false;
  reg.OpenKey(
    'Software\Microsoft\Windows\CurrentVersion\Policies\Explorer',
              false);
  reg.ReadBinaryData('NoDriveTypeAutoRun',
                     AutoRunSetting ,
                     sizeof(AutoRunSetting));
  if bOn then
    AutoRunSetting := AutoRunSetting and not (1 shl 5)
  else
    AutoRunSetting := AutoRunSetting or (1 shl 5);
  reg.WriteBinaryData('NoDriveTypeAutoRun',
                      AutoRunSetting ,
                      sizeof(AutoRunSetting));
  reg.CloseKey;
  reg.free;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if IsCdAutoRunOn then
    ShowMessage('CD AutoRun Is On') else
    ShowMessage('CD AutoRun Is Off');
end;


procedure TForm1.Button2Click(Sender: TObject);
begin
  SetCdAutoRun(True);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  SetCdAutoRun(False);
end;

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