^{DMUS_OBJECTDESC}

The DMUS_OBJECTDESC structure is used to describe a loadable object. This structure is passed to the IDirectMusicLoader8::GetObject method to identify the object that the loader should retrieve from storage. Information about an object is retrieved in this structure by the IDirectMusicLoader8::EnumObject and IDirectMusicObject8::GetDescriptor methods.

Syntax

typedef struct _DMUS_OBJECTDESC {
  DWORD         dwSize;
  DWORD         dwValidData;
  GUID          guidObject;
  GUID          guidClass;
  FILETIME      ftDate;
  DMUS_VERSION  vVersion;
  WCHAR         wszName[DMUS_MAX_NAME];
  WCHAR         wszCategory[DMUS_MAX_CATEGORY];
  WCHAR         wszFileName[DMUS_MAX_FILENAME];
  LONGLONG      llMemLength;
  LPBYTE        pbMemData;
  IStream*      pStream
} DMUS_OBJECTDESC, *LPDMUS_OBJECTDESC;

Members

dwSize

Size of the structure, in bytes. This member must be initialized to sizeof(DMUS_OBJECTDESC) before the structure is passed to any method.

dwValidData

Flags describing which members are valid and giving further information about some members. The following values are defined:

guidObject

Unique identifier for this object.

guidClass

Unique identifier for the class of object. See DirectMusic Component GUIDs.

ftDate

Date that the object was last edited.

vVersion

DMUS_VERSION structure containing version information.

wszName

Name of the object.

wszCategory

Category for the object.

wszFileName

File path. If DMUS_OBJ_FULLPATH is set, this is the full path; otherwise, it is the file name. If the IDirectMusicLoader8::SetSearchDirectory method has been called, this member must contain only a file name.

llMemLength

Size of data in memory.

pbMemData

Pointer to data in memory. Do not use this value except when loading from a resource contained in the executable file.

pStream

Address of the IStream interface of a custom stream that can be used to load the object into memory. In most cases this value should be NULL.See Remarks.

Remarks

At least one of wszName, guidObject, and wszFileName must contain valid data to retrieve the object by using the IDirectMusicLoader8::GetObject method.

The name and category strings use 16-bit characters in the WCHAR format, not 8-bit ANSI characters. Be sure to convert as appropriate. You can use the C library mbstowcs function to convert from multibyte to Unicode and the wcstombs function to convert from Unicode back to multibyte.

Instead of passing on object descriptor to IDirectMusicLoader8::GetObject or IDirectMusicLoader8::SetObject with a filename or memory pointer, an application can pass a stream. This is done by setting the DMUS_OBJ_STREAM flag in dwValidData and a pointer to the stream in pStream. When the application calls GetObject, the loader saves the stream's current location, reads the object from the stream, and then restores the saved location. The application can continue reading from the stream without being affected by the call to GetObject.

When SetObject is called with a stream, the loader makes a clone of the stream object, and this clone is used if the object is later loaded. Thus an application can release a stream or continue to read from it after passing it to the loader by using SetObject. The actual data of the stream is not copied, so the application should not change or delete the data.

Requirements

  Header: Declared in dmusici.h.

See Also

• DirectMusic Structures