MidiFilterTrackEvents

DWORD WINAPI MidiFilterTrackEvents
(
	HANDLE hSequence, 
	WORD wTrack, 
	QWORD qwFirst, 
	QWORD qwLast, 
	DWORD dwFormat, 
	QWORD qwFilter, 
	LPBRELS_FILTERED_EVENT* lpFilteredEvents
);

This function gets a range of events of the specified type from a track.

Parameters

• hSequence: handle of the sequence from where the events will be copied.
• wTrack: index of the track from where the events will be copied.
• qwFirst: first value of the event range to copy.
• qwLast: last value of the event range to copy.
• dwFormat: format of the range. Use MIDI_INDEX for event positions or MIDI_TICKS for tick positions.
• qwFilter: types of events to get. See Remarks below.
• lpFilteredEvents: address of a BRELS_FILTERED_EVENT pointer which will contain the retrieved events.

Return values

Returns the number of retrieved events or zero if none is available or an error occurred. The reasons for an error are an invalid sequence handle, an invalid track index, an invalid event range or event type.

Remarks

You can use an apropriate combination of the following values in the parameter qwFilter:

You do not retrieve the events themselves, but their indexes. You can use functions like MidiEventGet to read the event data or call MidiGetTrackEvents to retrieve the actual data.

The function allocates the lpFilteredEvents events array. After you have finished with it, call MidiFreeBuffer to deallocate it.

The following example counts how many notes a track has:

Example

void NoteCount(HANDLE Sequence, WORD wTrack)
{
	int nFilters, nEvents;
	LPBRELS_FILTERED_EVENT lpFilter;
	char temp[256];

	// Event count
	nEvents = MidiTrackGet(Sequence, wTrack, EVENT_COUNT);

	// Retrieves notes and filters count
	nFilters = MidiFilterTrackEvents(Sequence, wTrack, 0, nEvents-1, MIDI_INDEX, FILTER_NOTES, &lpFilter);

	// Releases the allocated array
	MidiFreeBuffer(lpFilter);

	// Shows the count
	itoa(nFilters, (char*) &temp, 10);
	MessageBox(NULL, (char*) &temp, "Note count", MB_OK);
};

Further information

Released in November 19th, 2003
Updated in April 29th, 2004
Property of Breno de Lima Sarmento
Home page: http://www27.brinkster.com/brels
E-mail: [email protected]
ICQ: 78977999 ()