Screen Saver and Windowed Mode

I seem to remember some discussion a while back about making BMax itself more resistant to screensavers interrupting it, but I don't recall the details. In any case, I looked around and found a thread on it (by netmaestro & Indiepath) with a solution, resulting in this code (not cross-platform, it's Windows-only, but that's one down and two to go):

' Below is from <a href="http://www.blitzbasic.com/Community/posts.php?topic=48372" target="_blank">http://www.blitzbasic.com/Community/posts.php?topic=48372</a>


Import "-luser32"

Extern "win32"
	Function SystemParametersInfoW(stuff1:Int,Stuff2:Int,Stuff3:Int,Stuff4:Int) = "SystemParametersInfoW@16"
EndExtern
Const SPI_SETSCREENSAVEACTIVE	:Int = 17
Const SPIF_SENDWININICHANGE	:Int = 2

SystemParametersInfoW(SPI_SETSCREENSAVEACTIVE, False, Null, SPIF_SENDWININICHANGE) ' saver off

Local start = MilliSecs()
Graphics 800,600',32,85 '<-uncomment for full screen
Repeat
	Cls
	DrawText ( MilliSecs() - start ) / 1000, 10,10
	Flip
	' below reenables it after 70 seconds (with a 1 minute delay, it does kick in at 130 secs)
	'If( ( MilliSecs() - start ) / 1000 ) = 70 ..
	'  SystemParametersInfoW(SPI_SETSCREENSAVEACTIVE, True, Null, SPIF_SENDWININICHANGE) ' saver on

Until KeyDown(KEY_ESCAPE)

SystemParametersInfoW(SPI_SETSCREENSAVEACTIVE, True, Null, SPIF_SENDWININICHANGE) ' saver on



Rem
	There's also this, from <a href="http://www.devx.com/vb2themax/Tip/19033" target="_blank">http://www.devx.com/vb2themax/Tip/19033</a> 
	which provides additional functionality that could be converted:

	Private Const SPI_SETSCREENSAVEACTIVE = 17
	Private Const SPI_GETSCREENSAVEACTIVE = 16
	Private Const SPIF_SENDWININICHANGE = &H2
	Private Const SPIF_UPDATEINIFILE = &H1
	
	Private Declare Function SystemParametersInfo Lib "user32" Alias _
	    "SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, _
	    ByRef lpvParam As Any, ByVal fuWinIni As Long) As Long
	
	' return the Enabled state of the screen saver
	
	Function GetScreenSaverState() As Boolean
	    Dim result As Long
	    SystemParametersInfo SPI_GETSCREENSAVEACTIVE, 0, result, 0
	    GetScreenSaverState = (result <> 0)
	End Function
	
	' enable or disable the screen saver
	'
	' if second argument is true, it writes changes in user's profile
	' returns True if the operation was successful, False otherwise
	
	Function SetScreenSaverState(ByVal enabled As Boolean, _
	    Optional ByVal PermanentChange As Boolean) As Boolean
	    Dim fuWinIni As Long
	    If PermanentChange Then
	        fuWinIni = SPIF_SENDWININICHANGE Or SPIF_UPDATEINIFILE
	    End If
	    SetScreenSaverState = SystemParametersInfo(SPI_SETSCREENSAVEACTIVE, enabled, _
	        ByVal 0&, fuWinIni) <> 0
	End Function
EndRem

In my tests (setting my saver to a 1-minute delay), I found that the saver wouldn't a start in fullscreen or windowed while a BlitzMax program was running, even without the "turn off" function above - I think that might be BlitzMax being resistant as I seem to recall reading. Actually, the saver did start in windowed mode (my cursor briefly became an arrow/hourglass at the 1-minute mark), but didn't appear on screen (or interfere with my BlitzMax program's window) until I pressed Escape to end the program, at which point I saw my saver.

With the above code, though, that didn't happen. So it seems to disable the saver for real. I added the re-enable call to make sure that the saver would come back up after this program finished, and it did. I also tried out the commented-out test to see if the saver could be re-enabled after 70 seconds, while the program was running and it worked (the hourglass didn't appear at 60 seconds, but did at 130 seconds).