Win32 getmessage loop stops executing when App window looses focus..! i want to run a infinite loop in my application without stopping - win32gui

Question

Win32 getmessage() loop stops executing when App window looses focus..! i want to run a infinite loop in my application without stopping...
The program works flawless when the mouse pointer moves on the window,as it raises a event and the getmessage processes,but when the application window looses its focus or the mouse is not over it,it STOPS!...
i have a function which needs to be called continuously even when the win32 app is minimized or lost focus...
i am calling the function like this...
MSG msg;
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
showFrame();
}
i know,only when any event is raised the getmessage processes it and in turn the showFrame() function is called,but i want to call the function continuously...
please give me a clue how can i achieve it or do i need to use threading??

Answer 1

GetMessage() blocks until there is a message available to retrieve. If you don't want to wait, then use PeekMessage() instead:
MSG msg;
do
{
...
while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
...
}
...
}
while (...);
You can also use either GetQueueStatus() or MsgWaitForMultipleObjects() to detect when there are messages available before then retrieving them, eg:
MSG msg;
do
{
...
if (GetQueueStatus(QS_ALLINPUT))
{
while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
...
}
}
...
}
while (...);
MSG msg;
do
{
...
if (MsgWaitForMultipleObjects(0, NULL, FALSE, 0, QS_ALLINPUT) == WAIT_OBJECT_0)
{
while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
...
}
}
...
}
while (...);
Alternatively, you can use SetTimer() to post periodic WM_TIMER messages to the queue, and then your loop can show the frames each time it receives that message.
Alternatively, use a standard GetMessage() loop, and have a separate thread drive your frame logic. Whenever it needs to show a new frame, it can post a user-defined message to the main thread queue so your loop can show the frame.