CMsg class
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The CMsgThread class provides support for a worker thread to which requests can be posted asynchronously instead of sent directly. The CAMThread class provides a worker thread to which single requests can be sent. Only one client can make a request at a time, and the client blocks until the worker thread has completed the request. By contrast, the CMsgThread class provides a worker thread to which any number of requests can be posted. The requests (in the form of a CMsg object) are queued and executed in order, asynchronously. No reply or return value is received.
| Data Members | Description |
|---|---|
| dwFlags | Flag parameter to the request code. |
| lpParam | Data required by the worker thread as parameter or return values. This data should not be stack-based, as it will be referenced some time after completing the queuing operation. |
| pEvent | Event object that a worker thread can signal to indicate the completion of the operation. |
| uMsg | Request code that is defined by the client of the thread class and understood by the overridden worker thread function. |
| Member Functions | Description |
| CMsg | Constructs a CMsg object. |