BezelServices is not used to control ALS but to display visual
notification like the one you see when you change the audio volume, or
when you press the eject key.
Le 3 juin 08 à 20:58, Gabriel ROUSSEAU a écrit :
Hi,
There is one thing that should be accessible from UserDefaults or by
AppleScript, or some kind of CGDisplay or NSScreen methods, but it
is not the case.
On MacBooks Pro and PowerBooks (don't know for MacBooks and iBooks),
there is a feature called ALS (Ambient Light Sensors) in the
hardware. The computer know the ambint light level.
Thats cool, and it is used to automatically adjust keyboard
backlight and display brigthness. In System Preferences theses
features can be enabled or disabled.
I will concentrate on the Display side : In System Preferences, in
the Display Tab, there is a way to activate or deactivate the
feature. Great, but wait a minute ! It is the ONLY way to activate
or deactivate it !
No way to AppleScript this, no way to do this using defaults, no way
to change it programatically.
Why ? Because in fact, this feature is managed by a loginwindow
plugin called BezelServices.loginPlugin that resides in /System/
Library/LoginPlugins/
It seems that SystemPreferences is using a PrivateFramework to
communicate with loginwindow ; this Framework is called
"BezelServices.Framework".
Of course, since this is a private Framework, no way to activate or
deactivate ALS officialy, and it means no support, no
documentation :-(
I have managed to have some more info using classdump, Instruments
developer tool, but I am stuck. Here are all the info I have found :
– The BezelServices.plist preference file is only read and write at
startup and shutdown, or probably User session starting and
stopping. Thats means trying to change values in this plist are
useless.
– The BezelServices.Framework can be classdumped, here is the dump :
----------
/*
* Generated by class-dump 3.1.2.
*
* class-dump is Copyright (C) 1997-1998, 2000-2001, 2004-2007 by
Steve Nygard.
*/
#include "CDStructures.h"
@class NSMutableDictionary;
@interface BSFWClient : NSObject
{
NSMutableDictionary *addCall; // 4 = 0x4
// struct ProcessSerialNumber _process; // 8 = 0x8
}
- (id)init;
- (void)dealloc;
- (short)addCallback:(void *)fp8 ForType:(unsigned long)fp12;
- (short)removeCallbackForType:(unsigned long)fp8;
- (int)callbackCount;
- (BOOL)isValidEventType:(unsigned long)fp8;
- (unsigned short)handleBSProxyEvent:(CDAnonymousStruct1)fp8;
@end
----------
/*
* Generated by class-dump 3.1.2.
*
* class-dump is Copyright (C) 1997-1998, 2000-2001, 2004-2007 by
Steve Nygard.
*/
/*
struct ProcessSerialNumber {
unsigned int highLongOfPSN;
unsigned int lowLongOfPSN;
};
*/
typedef struct {
unsigned int _field1;
unsigned int _field2;
unsigned int _field3;
unsigned int _field4[6];
} CDAnonymousStruct1;
-----------
/*
* Generated by class-dump 3.1.2.
*
* class-dump is Copyright (C) 1997-1998, 2000-2001, 2004-2007 by
Steve Nygard.
*/
@protocol BezelServicesWireProtocol
- (BOOL)registerProxyClient:(id)fp8 ForProcess:(id)fp12;
- (BOOL)unregisterProxyClientForProcess:(id)fp8;
- (id)preference;
- (int)setPreference:(id)fp8;
- (id)objectForPrefKey:(id)fp8;
- (int)setObject:(id)fp8 forPrefKey:(id)fp12;
- (int)ambientFeatureAvailable;
- (int)isKeyboardSaturated:(int *)fp8;
- (void)setKeyboardHold:(int)fp8;
- (void)setDisplayHold:(int)fp8;
- (void)setKeyboardValue:(float)fp8;
- (void)setDisplayValue:(float)fp8;
- (void)kernelPreferenceChanged:(id)fp8;
- (void)kernelPreferenceCreate:(id)fp8 ResetToDefaults:(BOOL)fp12;
- (int)remoteControlFeatureAvailable;
- (void)remoteUIToggle;
- (void)handleRemoteEventWithPage:(unsigned short)fp8 usage:
(unsigned short)fp12 flags:(unsigned short)fp16 value:(long)fp20;
@end
-----------
Interesting, we can see that the BezelServicesWireProtocol is what
we need ! But wait, what object conforms to this protocol ? How to
get an instance ? What the hell is a WireProtocol ?
To have an idea, I have used Instruments to sample SystemPreferences
exactly when I click the checkbox to change the ALS setting, and I
have found this :
Library Symbol Name
...
AppKit -[NSApplication sendAction:to:from:]
Brightness 0x1667f01a
BezelServices BSSetPreferenceBool
CoreFoundation _CF_forwarding_prep_0
...
Very interesting, whe have a BezelServices Framework object using
BSSetPreferenceBool ! Exactly what I want, but I don't know the
Class of this object, the way to instantiate it, etc… I am still
stuck.
What is this "Brightness" library ? Another Private Framework ? I am
lost at this point.
So, if someone have an idea, that would be kind. The only tihng I
want to do is activate or deactivate this ALS setting. I am not
really insterested in the reverse engineering challenge or anything
like that, only to find a way to activate or deactivate this ALS
thing from my code.
Regards._______________________________________________
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