Associating files programatically

Hi all.

I have a small program which I use when I have to restore some file association silently modified by a new program installed. For instance I have recently installed VideoPad and it has associated many video files with itself without prompting for this. The code (working perfectly some time ago) is something like:

Extension := '.avi';
Prog := 'C:\Program files\VideoLAN\VLC\vlc.exe';

procedure writeAssociation(Extension, Prog: string);
var
  reg: TRegistry;
  Log: string;
begin
  Log := '';
  reg := TRegistry.Create;
  try
    try
      reg.RootKey := HKEY_CLASSES_ROOT;
      reg.LazyWrite := false;
      reg.OpenKey(Extension + '\shell\open\command', true);
      reg.WriteString('', Prog + ' %1');
      reg.CloseKey;
      reg.OpenKey(Extension + '\DefaultIcon', true);
      reg.WriteString('', Prog + ',0');
      reg.CloseKey;
      Log := 'File type ' + Extension + ' is now associated with ' + Prog;
    except
      Log := 'Association failed for file type ' + Extension;
    end;
  finally
    reg.free;
  end;
  mmo1.Lines.Add(Log);
end;

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Now this code changes the registry values correctly, but avi files are still opened by VideoPad when I double-click on them and the icon is not vlc icon but VideoPad one.

Now, my problem is not to reassociate the avi extension with vlc: I can do it manually. My problem is how to write a program which set the files associations in the registry and makes these associations be respected by Windows. That is, I have to understand why the registry values set by my code above are ignored by Windows.

Hope to have been clear.

Thanks in advance for any advice.

Cheers
Marco
LVL 31
Marco GasiFreelancerAsked:
Who is Participating?
 
Sinisa VukConnect With a Mentor Commented:
try my example:

uses ...  Registry, ShlObj;

procedure AssocFileExt(sExt, sFileName:String);
var
  reg: TRegistry;
  sExtWOPoint: String;
  buf: Byte;
begin
  sExt := Trim(sExt);
  if Length(sExt) = 0 then exit;
  sExtWOPoint := sExt;
  if sExtWOPoint[1] = '.' then Delete(sExtWOPoint, 1, 1);
  buf := 0;
  
  reg := TRegistry.Create;
  try
    reg.RootKey := HKEY_CLASSES_ROOT;
    if reg.OpenKey('\'+sExt, True) then
    begin
      reg.WriteString('', sExtWOPoint + 'file');
      reg.CloseKey;
      reg.OpenKey('\'+sExt+'\OpenWithList\ehshell.exe\', True);
      reg.CloseKey;
      if reg.OpenKey('\'+sExt+'\OpenWithProgIds\', True) then
      begin
        reg.WriteBinaryData(sExtWOPoint + 'file', buf, SizeOf(buf));
      end;
      reg.CloseKey;
      if reg.OpenKey('\'+sExtWOPoint + 'file\shell\open\command\', True) then
        reg.WriteString('', '"'+sFileName+'" "%1"');
      reg.CloseKey;
    end;

    reg.RootKey := HKEY_CURRENT_USER;
    if reg.OpenKey('\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\'+sExt+'\OpenWithProgids\', True) then
    begin
      reg.WriteBinaryData('avifile', buf, SizeOf(buf));
    end;
  finally
    reg.Free;
  end;
  SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST, 0, 0);
end;

....
AssocFileExt('.avi', 'C:\Program files\VideoLAN\VLC\vlc.exe');

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... and here is another example

... for per user ext registration (and avoid admin rules) there is similar values under
HKEY_CURRENT_USER\SOFTWARE\Classes
0
 
accountsworldsCommented:
1) I wanted the option to "open with" from all file types so i added
  reg := TRegistry.Create;
  reg.RootKey := HKEY_CLASSES_ROOT;
  reg.LazyWrite := false;
  reg.OpenKey('*\OpenWithList\EncryptionSystem', true);
  reg.WriteString('','C:\Program Files\EncryptionSystem\EncryptionSystem.exe "%1"');
  reg.CloseKey;
  reg.free;

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If I look in the registry using regedit it's sure there as it should seem to be but when I right click on a file and select Open With it's not there...

So I then added this
 
 reg.OpenKey('*\shell\Encrypt\command', true);
  reg.WriteString('','C:\Program Files\EncryptionSystem\EncryptionSystem.exe "%1"');
  reg.CloseKey;

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Source: http://stackoverflow.com/questions/590892/windows-registry-file-association-menu
0
 
Marco GasiFreelancerAuthor Commented:
Sorry, but i really don't see a solution in the source you posted.
0
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Marco GasiFreelancerAuthor Commented:
Hi sinisav, ho do you do? :-)

Yes your code works: I didn't test it yet, but I know beacause I understood that I can simply empty the data of the default value to make the new association work.

Many thanks: you're becoming my personal expert ;-)

Merry Christmas and Happy New Year!
0
 
Marco GasiFreelancerAuthor Commented:
Merry Christmas and Happy New Year!
0
 
Sinisa VukCommented:
Merry Christmas and successful New Year to you, your family and to all who comes to experts-exchange to expand their knowledge or share it as well.
0
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