创建游戏内核（21）【OO改良版】

创建游戏内核（21）【OO改良版】

 

本篇是创建游戏内核（20）【OO改良版】的续篇，关于该内核的细节说明请参阅创建游戏内核（21）。

接口：

//======================================================================================
// This class encapsulates for downloadable sound.
//======================================================================================
typedef  class  DLS
{
public :
    DLS();
    ~DLS();

    IDirectMusicCollection8* get_dm_colletion();

    BOOL attach(SOUND_PTR sound);
    BOOL load( const   char * filename);
    BOOL free();

     long  get_num_patches();
     long  get_patch( long  index);
    BOOL exists( long  patch);

private :
    SOUND_PTR m_sound;
    IDirectMusicCollection* m_dm_collection;
} *DLS_PTR;

实现：

//------------------------------------------------------------------------------
// Constructor, zero member data.
//------------------------------------------------------------------------------
DLS::DLS()
{
    memset( this , 0,  sizeof (* this ));
}

//------------------------------------------------------------------------------
// Destructor, release DirectMusic resource.
//------------------------------------------------------------------------------
DLS::~DLS()
{
    free();
}

//------------------------------------------------------------------------------
// Release DirectMusic collection object.
//------------------------------------------------------------------------------
BOOL DLS::free()
{
     if (m_sound == NULL || m_sound->get_dm_loader() == NULL)
         return  FALSE;

     if (m_dm_collection)
    {
         if (FAILED(m_sound->get_dm_loader()->ReleaseObjectByUnknown(m_dm_collection)))
             return  FALSE;
    }

    release_com(m_dm_collection);
     return  TRUE;
}

//------------------------------------------------------------------------------
// Create DLS object.
//------------------------------------------------------------------------------
BOOL DLS::attach(SOUND_PTR sound)
{
    free();

    m_sound = sound;

     if (m_sound == NULL || m_sound->get_dm_loader() == NULL)
         return  FALSE;

     return  TRUE;
}

//------------------------------------------------------------------------------
// Load DirectMusic collection object from specified filename.
//------------------------------------------------------------------------------
BOOL DLS::load( const   char * filename)
{
    free();

     if (m_sound == NULL || m_sound->get_dm_loader() == NULL)
         return  FALSE;

    DMUS_OBJECTDESC _object_desc;

    ZeroMemory(&_object_desc,  sizeof (DMUS_OBJECTDESC));

    _object_desc.dwSize    =  sizeof (DMUS_OBJECTDESC);
    _object_desc.guidClass = CLSID_DirectMusicCollection;

     if (filename == NULL)
    {
         // get the default collection
        _object_desc.guidObject  = GUID_DefaultGMCollection;
        _object_desc.dwValidData = DMUS_OBJ_CLASS | DMUS_OBJ_OBJECT;
    }
     else
    {
         // get the colletion object
        _object_desc.dwValidData = DMUS_OBJ_CLASS | DMUS_OBJ_FILENAME | DMUS_OBJ_FULLPATH;
        mbstowcs(_object_desc.wszName, filename, MAX_PATH);
    }

    HRESULT _rv = m_sound->get_dm_loader()->GetObject(&_object_desc, 
                                IID_IDirectMusicCollection8, (LPVOID*)&m_dm_collection);    

     if (_rv != S_OK)
    {
         if (_rv == DMUS_E_LOADER_FAILEDCREATE)
            err_msg_box("The object could not be found or created.");
         else   if (_rv == DMUS_E_LOADER_FAILEDOPEN)
            err_msg_box("File open failed because the file does not exist or is locked.");
         else   if (_rv == DMUS_E_LOADER_FORMATNOTSUPPORTED)            
            err_msg_box("The object cannot be loaded because the data format is not supported.");
         else   if (_rv == DMUS_E_LOADER_NOCLASSID)
            err_msg_box("No class identifier was supplied in the object description.");
         else   if (_rv == E_FAIL)
            err_msg_box("The method did not succeed.");
         else   if (_rv == E_INVALIDARG)
            err_msg_box("Invalid argument. Often, this error results from failing to initialize the dwSize member"
                        " of a structure before passing it to the method.");
         else   if (_rv == E_OUTOFMEMORY)
            err_msg_box("Insufficient memory to complete the task.");
         else   if (_rv == E_POINTER)
            err_msg_box("An invalid pointer, usually NULL, was passed as a parameter.");
         else   if (_rv == REGDB_E_CLASSNOTREG)
            err_msg_box("The object class is not registered.");

         return  FALSE;
    }

     return  TRUE;
}

//------------------------------------------------------------------------------
// Return DirectMusic collection object.
//------------------------------------------------------------------------------
IDirectMusicCollection8* DLS::get_dm_colletion()
{
     return  m_dm_collection;
}

//------------------------------------------------------------------------------
// Return number of patches in DirectMusic collection.
//------------------------------------------------------------------------------
long  DLS::get_num_patches()
{
    DWORD _patch;
     long   _index = 0;

     // retrieves the patch number and name of an instrument by its index in the collection
     while (m_dm_collection->EnumInstrument(_index, &_patch, NULL, 0))
        ++_index;

     return  _index;
}

//------------------------------------------------------------------------------
// Return patch number by index of the instrument.
//------------------------------------------------------------------------------
long  DLS::get_patch( long  index)
{
    DWORD _patch;

     if (m_dm_collection == NULL)
         return  -1;

     if (FAILED(m_dm_collection->EnumInstrument(index, &_patch, NULL, 0)))
         return  -1;

     return  ( long ) _patch;
}

//------------------------------------------------------------------------------
// Judge whether specified patch exists.
//------------------------------------------------------------------------------
BOOL DLS::exists( long  patch)
{
    IDirectMusicInstrument8* _dm_instrument;

     if (m_dm_collection == NULL)
         return  FALSE;

     // retrieve an instrument by its patch number
     if (FAILED(m_dm_collection->GetInstrument(patch, &_dm_instrument)))
         return  FALSE;

    _dm_instrument->Release();

     return  TRUE;
}