BOOL PostMessage(
HWND hWnd, // handle of destination window
UINT Msg, // message to post
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);
Parameters
hWnd
Handle to the window whose window procedure is to receive the message. Two values have special meanings: Value Meaning
HWND_BROADCAST The message is posted to all top-level windows in the system, including disabled or invisible unowned windows, overlapped windows, and pop-up windows. The message is not posted to child windows.
NULL The function behaves like a call to PostThreadMessage with the dwThreadId parameter set to the identifier of the current thread.
Msg
Specifies the message to be posted.
wParam
Specifies additional message-specific information.
lParam
Specifies additional message-specific information.
Return Values
If the function succeeds, the return value is nonzero.If the function fails, the return value is zero. To get extended error information, callGetLastError. Res
Applications that need to communicate using HWND_BROADCAST should use the RegisterWindowMessage function to obtain a unique message for inter-application communication.If you send a message in the range below WM_USER to the asynchronous message functions (PostMessage, SendNotifyMessage, and SendMessageCallback), its message parameters can not include pointers. Otherwise, the operation will fail. The functions will return before the receiving thread has had a chance to process the message and the sender will free the memory before it is used.
HWND hWnd, // handle of destination window
UINT Msg, // message to post
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);
Parameters
hWnd
Handle to the window whose window procedure is to receive the message. Two values have special meanings: Value Meaning
HWND_BROADCAST The message is posted to all top-level windows in the system, including disabled or invisible unowned windows, overlapped windows, and pop-up windows. The message is not posted to child windows.
NULL The function behaves like a call to PostThreadMessage with the dwThreadId parameter set to the identifier of the current thread.
Msg
Specifies the message to be posted.
wParam
Specifies additional message-specific information.
lParam
Specifies additional message-specific information.
Return Values
If the function succeeds, the return value is nonzero.If the function fails, the return value is zero. To get extended error information, callGetLastError. Res
Applications that need to communicate using HWND_BROADCAST should use the RegisterWindowMessage function to obtain a unique message for inter-application communication.If you send a message in the range below WM_USER to the asynchronous message functions (PostMessage, SendNotifyMessage, and SendMessageCallback), its message parameters can not include pointers. Otherwise, the operation will fail. The functions will return before the receiving thread has had a chance to process the message and the sender will free the memory before it is used.
另一种是不进队消息,即发给窗口过程
postmessage就是前者,消息放到消息队列后,立即返回
而sendmessage发给窗口过程,等待处理完后才返回