Hi..

I have been looking for the same thing (read the toggle status, which
will not work at all)!!

There is one command that may be worth looking at:

SysLCDBrightness(Boolean set, UInt8 newBrightnessLevel)

in SystemMgr.h file.

Robert

--- In [EMAIL PROTECTED], Jeff Ishaq <[EMAIL PROTECTED]> wrote:
> At 08:34 PM 6/27/2003 -0700, [EMAIL PROTECTED] wrote:
> >Hello,
> >
> >    I need to check whether backlight is on or off.
> >How can i check?
> 
> Good question, I couldn't find a good way to tell for sure whether the 
> backlight is on.  Surely there's a bit somewhere in the low-memory
globals 
> that will tell you precisely the information you need, but I suspect
you'd 
> need to become a Palm OS licensee to get the official documentation
(and 
> support) for this bit.
> 
> I found a few ways of getting close to the info you need.  :)
> 
> I know in OSes 3.5 and earlier, there is a HwrBacklight() function you 
> could call to get the status of the backlight.  I think it was an 
> undocumented function that you just had to trap into manually with
inline 
> assembly.  That API has been deprecated in newer versions of Palm OS.
> 
> There is a vchrBacklight character defined in Chars.h that appears to 
> toggle the state of the backlight.  I would imagine this key gets
enqueued 
> when the user holds down the power-on button long enough to toggle the 
> backlight.  When the OS gets ahold of this character, it calls internal 
> routine(s) to physically toggle the backlight's state.  Your app can 
> intercept these characters in your event loop, and this will tell
you when 
> the user has toggled the backlight while your app is running. 
However, it 
> won't give you any indication of the state of the backlight, so
might not 
> be of any use to you.
> 
> Other ways to get close to the information you need is to use the 
> notification manager to determine when the device is asleep or
awake.  You 
> can use SysBatteryInfo() to determine if the device is on the cradle 
> (charging) and combine that with the state of
prefStayLitWhenPluggedIn (aka 
> stayLitWhenPluggedIn) OS preference.
> 
> Maybe somebody else on this forum has a better technique?
> 
> -Jeff Ishaq
> 
> 
> 
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