Re: animation in MFC with threading
On Oct 5, 8:24 pm, Jim <j...@trainplayer.com> wrote:
Thanks to both of you. This is just the kind of guidance I was
looking for. I'll put a new sheet on the drawing board and start
over.
An example of a time-consuming operation is: as the user moves the
mouse, figuring out what to highlight. It might be necessary to look
at a thousand objects to find the one at the cursor position. I don't
see creating a new thread every time the user moves the mouse. If
there is some worker thread running to do such calculations, then it
becomes a matter of telling it what to do and getting back the
answer. I can think of some hacks, but I don't know an elegant way to
do this.
Each thread has a message queue. You can create your secondary thread
(a CWinThread derived class) so that it accepts requests that tell it
what to do via its message queue. The main thread uses
PostThreadMessage, the secondary thread puts ON_THREAD_MESSAGE into
its message map. To send the answer back to the main thread the
secondary thread uses PostMessage to a window in the main thread,
which uses ON_MESSAGE in its message map to catch the message.
In short: if it makes sense only to thread lengthy jobs, what about a
lot of semi-lengthy ones?
-- Jim
If these semi-lengthy jobs are jittering your animation objectionally,
then yes.