ID Number: Q36324
3.00
WINDOWS
Summary:
A Windows application that performs a long, background task, such as
repaginating a word processing document, can be designed in a number
of different ways.
A polling task can be accomplished by setting a timer to fire at the
desired interval. Many nonpolling tasks can be performed in pieces.
Although Windows does not have a method to schedule processing based
on overall system load, an application can wait until there are no
other messages to be processed by that application before proceeding.
This article discusses the code required to implement this method.
More Information:
It is important that each piece of the task be relatively small. This
allows Windows to devote processing time to other applications running
in the system. Similarly, once the task is complete, it is important
that the application signal that it is idle. This allows Windows to
optimize its performance and to prolong battery life on portable
computers.
The following code skeleton demonstrates how this might be
implemented:
WinMain
{
do application initialization
fBackgroundToDo = TRUE;
fRunning = TRUE;
while (fBackgroundToDo && fRunning)
{
if (fBackgroundToDo)
{
if ((PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
if (msg.message == WM_QUIT)
{
fRunning = FALSE;
break;
}
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
fBackgroundToDo = DoABitOfBackground();
}
else if ((fRunning = GetMessage(&msg, NULL, NULL, NULL)) != 0)
{
TranslateMessage(&msg);
DispatchMessage(&msg);
fBackgroundToDo = IsThereBackgroundToDo();
}
}
}
Additional reference words: 3.00