DMUS_PMSG

The DMUS_PMSG structure contains information common to all DirectMusic messages. Because C does not support inheritance, the members of this structure are included in all message types (including DMUS_PMSG itself) by the inclusion of the DMUS_PMSG_PART macro, which expands to the syntax shown here.

typedef struct DMUS_PMSG {
    DWORD              dwSize;
    REFERENCE_TIME     rtTime;
    MUSIC_TIME         mtTime;
    DWORD              dwFlags;
    DWORD              dwPChannel;
    DWORD              dwVirtualTrackID;
    IDirectMusicTool*  pTool;
    IDirectMusicGraph* pGraph;
    DWORD              dwType;
    DWORD              dwVoiceID;
    DWORD              dwGroupID;
    IUnknown*          punkUser;
} DMUS_PMSG;

dwSize

Size of the structure, in bytes. This member is initialized by IDirectMusicPerformance::AllocPMsg.

rtTime

Reference time at which the message is to be played, modified by dwFlags. Used only if DMUS_PMSGF_REFTIME is present in dwFlags.

mtTime

Music time at which the message is to be played, modified by dwFlags. Used only if DMUS_PMSGF_MUSICTIME is present in dwFlags.

dwFlags

Various bits (see DMUS_PMSGF_FLAGS and DMUS_TIME_RESOLVE_FLAGS). Must contain DMUS_PMSGF_REFTIME or DMUS_PMSGF_MUSICTIME.

dwPChannel

Performance channel (PChannel). The port, channel group, and MIDI channel can be derived from this value by using the IDirectMusicPerformance::PChannelInfo method. Set this value to 0 for messages that are not channel-specific, such as tempo messages.

dwVirtualTrackID

Identifier of the track. Set to 0 if the message is not being sent by a track.

pTool

Address of the tool interface. Can be set by using IDirectMusicGraph::StampPMsg, or can be NULL if the message is not to go to tools other than the output tool.

pGraph

Address of the tool graph interface. Can be set by using IDirectMusicGraph::StampPMsg, or can be NULL if the message is not to go to tools other than the output tool.

dwType

Message type (see DMUS_PMSGT_TYPES).

dwVoiceID

Reserved for future use. Should be set to 0.

dwGroupID

Identifier of the track group or groups that the message belongs to if the message is being generated by a track. (Tracks are assigned to groups in the IDirectMusicSegment::InsertTrack method.) For most purposes, this value can be 0xFFFFFFF.

punkUser

Address of an IUnknown interface supplied by the application. This pointer is always released when the message is freed. If the application wants to retain the object, it should call AddRef before the message is freed. If the message does not need a COM pointer, this value should be NULL.

Remarks

The DMUS_PMSG structure is used by itself for messages containing the following values in the dwType member:

DMUS_PMSGT_STOP

Sending a message of this type stops the performance at the specified time.

DMUS_PMSGT_DIRTY

When a control segment starts or ends, all tools in the segment and performance graphs receive a message of this type, indicating that if they cache data from GetParam calls, they must call GetParam again to refresh their data. Tools that want to receive this message type must indicate this through a call to IDirectMusicTool::GetMediaTypes. Tools in the performance graph receive one copy of the message for each segment in the performance. Such tools can safely ignore the extra messages with the same time stamp.

Requirements

  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in dmusici.h.

See Also

IDirectMusicPerformance::SendPMsg