Screen Saver

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3 total messages Started by M J Heneghan Thu, 10 Aug 2006 06:18

#3256

Author: M J Heneghan
Date: Thu, 10 Aug 2006 06:18

21 lines
1523 bytes

I want to ensure the screensaver is turned off when running a demo video 
running under windows XP.  At the beginning of the routine calling the demo 
I have added

 bool *IsScreenSave;
 SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, IsScreenSave, 0);
 SystemParametersInfo(SPI_SETSCREENSAVEACTIVE, FALSE, NULL, 
SPIF_SENDCHANGE);
....
then call the demo using
spawnl(P_WAIT, demo, demo, NULL);
... and at end of routine

 if (IsScreenSave) SystemParametersInfo(SPI_SCREENSAVEACTIVE, TRUE, NULL, 
SPIF_SENDCHANGE);

however, the screensaver still kicks in.  What am I missing?  Thanks in 
advance.

-- 
M J Heneghan.

Re: Screen Saver

#3257

Author: Remy Lebeau (TeamB)
Date: Thu, 10 Aug 2006 06:48

26 lines
1886 bytes

"M J Heneghan" <mjheneghan@ntlworld.com> wrote in message
news:44dacfb0$1@newsgroups.borland.com...

>  bool *IsScreenSave;
>  SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, IsScreenSave, 0);

That is not the correct way to pass the boolean.  You have to use the '&'
operator instead:

    BOOL IsScreenSave;
    SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, &IsScreenSave, 0);

> however, the screensaver still kicks in.

As it should be.  You are not preventing it from running at all.
SPI_SETSCREENSAVEACTIVE does not deactive the screensaver if it is already
running.  It is only a flag to tell the OS whether the screensaver is
running or not.  Screensavers use SPI_SETSCREENSAVEACTIVE when they run.  If
anything, you should be setting SPI_SETSCREENSAVEACTIVE to TRUE instead of
FALSE to trick the OS into thinking a screensaver is running when none
actually is.  That way, the actual screen saver will not kick in until you
set SPI_SETSCREENSAVEACTIVE back to FALSE later.


Gambit

Re: Screen Saver

#3258

Author: M J Heneghan
Date: Thu, 10 Aug 2006 14:47

34 lines
2179 bytes

Thanks for the information.  I have a lot to learn!


"Remy Lebeau (TeamB)" <no.spam@no.spam.com> wrote in message 
news:44dae467$1@newsgroups.borland.com...
>
> "M J Heneghan" <mjheneghan@ntlworld.com> wrote in message
> news:44dacfb0$1@newsgroups.borland.com...
>
>>  bool *IsScreenSave;
>>  SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, IsScreenSave, 0);
>
> That is not the correct way to pass the boolean.  You have to use the '&'
> operator instead:
>
>    BOOL IsScreenSave;
>    SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, &IsScreenSave, 0);
>
>> however, the screensaver still kicks in.
>
> As it should be.  You are not preventing it from running at all.
> SPI_SETSCREENSAVEACTIVE does not deactive the screensaver if it is already
> running.  It is only a flag to tell the OS whether the screensaver is
> running or not.  Screensavers use SPI_SETSCREENSAVEACTIVE when they run. 
> If
> anything, you should be setting SPI_SETSCREENSAVEACTIVE to TRUE instead of
> FALSE to trick the OS into thinking a screensaver is running when none
> actually is.  That way, the actual screen saver will not kick in until you
> set SPI_SETSCREENSAVEACTIVE back to FALSE later.
>
>
> Gambit
>
>

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