The GetQueueStatus function returns flags that indicate the type of messages found in the calling thread’s message queue.
DWORD GetQueueStatus(
|
UINT flags |
// queue-status flags |
|
); |
|
Value |
Meaning |
|
QS_ALLEVENTS |
An input, WM_TIMER, WM_PAINT, WM_HOTKEY, or posted message is in the queue. |
|
QS_ALLINPUT |
Any message is in the queue. |
|
QS_ALLPOSTMESSAGE |
A posted message (other than those listed here) is in the queue. |
|
QS_HOTKEY |
A WM_HOTKEY message is in the queue. |
|
QS_INPUT |
An input message is in the queue. |
|
QS_KEY |
A WM_KEYUP, WM_KEYDOWN, WM_SYSKEYUP, or WM_SYSKEYDOWN message is in the queue. |
|
QS_MOUSE |
A WM_MOUSEMOVE message or mouse-button message (WM_LBUTTONUP, WM_RBUTTONDOWN, and so on). |
|
QS_MOUSEBUTTON |
A mouse-button message (WM_LBUTTONUP, WM_RBUTTONDOWN, and so on). |
|
QS_MOUSEMOVE |
A WM_MOUSEMOVE message is in the queue. |
|
QS_PAINT |
A WM_PAINT message is in the queue. |
|
QS_POSTMESSAGE |
A posted message (other than those listed here) is in the queue. |
|
QS_SENDMESSAGE |
A message sent by another thread or application is in the queue. |
|
QS_TIMER |
A WM_TIMER message is in the queue. |
The high-order word of the return value indicates the types of messages currently in the queue. The low-order word indicates the types of messages that have been added to the queue and that are still in the queue since the last call to the GetQueueStatus, GetMessage, or PeekMessage function.
The presence of a QS_ flag in the return value does not guarantee that a subsequent call to the GetMessage or PeekMessage function will return a message. GetMessage and PeekMessage perform some internal filtering that may cause the message to be processed internally. For this reason, the return value from GetQueueStatus should be considered only a hint as to whether GetMessage or PeekMessage should be called.
The QS_ALLPOSTMESSAGE and QS_POSTMESSAGE flags differ in when they are cleared. QS_ALLPOSTMESSAGE is cleared when you call GetMessage or PeekMessage without filtering messages (wMsgFilterMin and wMsgFilterMax are 0). QS_POSTMESSAGE is cleared when you call GetMessage or PeekMessage, whether or not you are filtering messages.