Generating a Class Identifier for a File Filter

Every file filter must be given a unique CLSID, which identifies class objects to OLE. CLSIDs are universally unique identifiers (UUIDs), also called globally unique identifiers (GUIDs). The file filter's CLSID must be included in your application and it must be registered with the operating system when your application is installed.

If the file filter supports both importing and exporting, a unique CLSID must be associated with each file filter that is to be registered for the respective import and export registry setting.

The GUID Generator tool lets you generate a GUID that you can use to identify your file filter. A GUID Generator application, named Guidgen.exe, is provided with Microsoft Visual C++. The GUID Generator calls the CoCreateGuid function to generate a new GUID. It also lets you copy the GUID to the clipboard for insertion into your application's source code using one of the following formats:

• IMPLEMENT_OLECREATE macro format

  Defined in an IMPLEMENT_OLECREATE macro, which allows instances of a CCmdTarget-derived class to be created by Automation clients. For example:

  // {CA761230-ED42-11CE-BACD-00AA0057B223}
  IMPLEMENT_OLECREATE(<<class>>, <<external_name>>, 
  0xca761230, 0xed42, 0x11ce, 0xba, 0xcd, 0x0, 0xaa,
  0x0, 0x57, 0xb2, 0x23);

• DEFINE_GUID macro format

  Defined in an IMPLEMENT_OLECREATE macro, which is included with Microsoft Visual C++ in the file Afxdisip.h. It allows instances of a CCmdTarget-derived class to be created by Automation clients. For example:

  // {CA761230-ED42-11CE-BACD-00AA0057B223}
  DEFINE_GUID(<<name>>, 
  0xca761230, 0xed42, 0x11ce, 0xba, 0xcd, 0x0, 0xaa, 0x0, 0x57, 0xb2, 0x23);
  

• Statically allocated structure format

  Declared as a statically allocated structure. For example:

  // {CA761232-ED42-11CE-BACD-00AA0057B223}
  static const GUID <<name>> = { 0xca761232, 0xed42, 0x11ce, 
  { 0xba, 0xcd, 0x0, 0xaa, 0x0, 0x57, 0xb2, 0x23 } };
  

• Registry entryf

  Specified in a form suitable for registry entries or registry editor scripts. For example:

  {CA761233-ED42-11CE-BACD-00AA0057B223}