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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;
}