Message Function

The Wxutil.h header file in the DirectShow base classes provides a helper function for processing messages.

Function Description
WaitDispatchingMessages Waits for a for the HANDLE hObject before dispatching messages. While waiting, messages sent to windows on the thread by SendMessage will be processed.

WaitDispatchingMessages

Waits for a for the HANDLE hObject before dispatching messages. While waiting, messages sent to windows on the thread by SendMessage will be processed.

DWORD WINAPI WaitDispatchingMessages(
  HANDLE hObject,
  DWORD dwWait,
  HWND hwnd = NULL,
  UINT uMsg = 0
  );

Parameters

hObject: Handle of object to wait for.
dwWait: Time-out interval in milliseconds.
hwnd: Handle to a window.
uMsg: Win32 message.

Return Values

If the function succeeds, the return value indicates the event that caused the function to return. If the function fails, the return value is WAIT_FAILED.

The return value on success is one of the following values:

Value Meaning
WAIT_ABANDONED The specified object is a mutex object that was not released by the thread that owned the mutex object before the owning thread terminated. Ownership of the mutex object is granted to the calling thread, and the mutex is set to nonsignaled.
WAIT_OBJECT_0 The state of the specified object is signaled.
WAIT_TIMEOUT The time-out interval elapsed, and the object's state is nonsignaled.

Remarks

This function enables sent messages to be processed while waiting for a handle to a window. Use this function to wait for an object to be processed and to perform mutually exclusive operations, consequently avoiding possible deadlocks in objects with windows.

This helper function is similar to the Win32 WaitForSingleObject function.

Function	Description
WaitDispatchingMessages	Waits for a for the HANDLE hObject before dispatching messages. While waiting, messages sent to windows on the thread by SendMessage will be processed.

Value	Meaning
WAIT_ABANDONED	The specified object is a mutex object that was not released by the thread that owned the mutex object before the owning thread terminated. Ownership of the mutex object is granted to the calling thread, and the mutex is set to nonsignaled.
WAIT_OBJECT_0	The state of the specified object is signaled.
WAIT_TIMEOUT	The time-out interval elapsed, and the object's state is nonsignaled.