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g-Lock, force-based phone locker

g-Lock is designed to change default Android lock pattern behaviour. In Android 1.x, the lock pattern is activated every time your device screen is powered off. With g-Lock you can now change this, and choose to use accelerometer or timer (or a combination of both) to control your Lock Pattern.
With accelerometer control, you can enable locking with a simple movement, or just prevent phone from locking when still moving.
g-Lock is extendable, its framework makes adding new lock schemes very easy, if you have some suggestions, you are welcome.

If you are in trouble, or this software does not match your expectations, please send a mail to the developer, we will do our best to solve the problem.

WARNING: If your device is one of these:
HTC Hero;
HTC Magic with latest firmware;
it is probable that accelerometer events are disabled while the screen is off, thus g-Lock force based events cannot work. This issue can affect also other devices based on same Android codebase. This is under investigation, please check here.

Like most Android applications, g-Lock must be installed from the Android Market. Installation steps do not differ from standard installation phases.
The full version is now available for purchase on the Android Market.

DEMO version limits
The demo version has the following limits:
  • the program will work for one week.

  • Android 1.5, 1.6
  • Android 2.0

g-Lock is controlling the Lock Pattern flag in the Security Settings with a different logic than Android. It is designed to enable locking on specific events, not related to the screen off event.
Current supported events are timer and accelerometer: it means you can control the locking logic by setting a delay (since screen off) or a specific accelerometer sequence.

Basic event is to set a timeout, g-Lock will enable the lock pattern after the required delay. This is the simplest way to control events, and also the one with lowest impact on battery life: when the screen goes off on Android devices, also the CPU is stopped to prevent battery usage, but this means also processes are suspended.

The second way to control the lock pattern is using the accelerometer: when the screen goes off, g-Lock starts listening to the accelerometer data flow, and tries to recognize the desired event. When this happens, g-Lock enables the lock pattern and stops controlling events. This explain why more battery usage is required in this case: while the screen is off, g-Lock must keep the CPU alive to process its data. This task does not require high CPU usage, and since the screen has the biggest impact on battery, you will not eat all of your battery. To prevent excessive use of accelerometer and CPU, you can combine accelerometer with timers.

After the first startup, g-Lock will check your configuration to make sure a lock pattern has already be defined. If you are not sure about the lock pattern, please check its shape in Security Settings before going off!

The main activity panel of g-Lock (screenshot 1) does not have many functions, it allows only to manually enable the lock and enter program settings (screenshot 2).

Setup example (How to recognize a device on the table): this will lock your device once it will be put on the table for at least 1 minute; enter g-Lock settings, click Lock action and select Timed without move. Click Timeout delay and select 1 minute delay. Set Sensibility level to 2 (medium high). Enable Notify when ready option. Under Notification options enable vibration. Now turn off the screen. Try moving the phone, the led should flash with a magenta color. Now put it on the table, the led should stop flashing after a while. Wait 1 minute (slightly more probably) and it should vibrate to notify you the lock action executed.

Testing configuration: with version 1.4 a new Test lock setup options has been added to settings; once the configuration is ready, you can use the test to verify if lock works as designed. You need to enable notification options to get feedback about locking. Once you get the notification, you can put screen off to test lock pattern. Click OK to terminate the test and restore locking status.

g-Lock settings
Settings are grouped in different sections to make them easier to identify.
  1. Disable g-Lock service can be used to turn off/on g-Lock functions without changing current settings.
  1. Lock settings group is related to possible events:
    1. Lock action defines which kind of event you want to enable
      1. None no action defined;
      1. Timed use only a delay;
      1. Force use a movement with a delay;
      1. Timed without move allows locking only if the phone is not moving for a predefined delay (e.g. you if leave it on your table it will lock, if you keep it with you it will not lock);
    1. Timeout delay allows selection of delay from screen off event;
    1. Tap Notification options to select which kind of notification you prefer when activating lock (screenshot 3); you can enable vibration, light flashing, ringtone play.
  1. Force settings group defines how to use accelerometer.
    1. Force type selects the kind of movement required to activate g-Lock;
      1. None nothing defined;
      1. Shake you have to shake your phone;
      1. Up Down Up put phone with screen up, then rotate until screen is facing down, then go up again;
      1. (left,right,up,down,push,pull) move phone in the direction. This is experimental code, and due to accelerometer design, it could be difficult to get an acceptable recognition for some movements. The phone must be held with the screen facing you, otherwise proper acceleration data cannot be analyzed.
    1. Sensibility level defines the minimal threshold to activate events, you need to try different values to suit your needs.
    1. Notify when ready will show a flashing magenta led when accelerometer sequence is starting, useful for testing.
  1. No lock options allows disabling locking:
    1. USB plugged does not lock if you are connected to a PC using the USB cable;
    1. AC plugged does not lock if you plugged the AC adapter.
  1. Locale settings: use this to change current user interface language, currently EN, IT, FR locales are supported (DE, NL to come).

Known problems
  • When many programs are using the CPU/accelerometer, it may happen that sensor events rate is not enough fast to allow proper analysys; enabling the 'Notify when ready' option, helps understanding such situations, mainly because the light does not start flashing. Be aware: if light is flashing, this does not means data rate is good.
  • For devices like HTC Hero/Magic (and possibly others) accelerometer events are disabled while the screen is off, thus g-Lock force based events cannot work. This issue can affect also other devices based on same Android codebase.

  • The hardware accelerometer in G1 phones is not extremely precise; the error associated to data flow is comparable to small phone movements. Also the orientation sensor can returns wrong values, making things ever worse. This makes difficult to recognize phone movement in 3D directions. E.g. if you rotate the phone around it, it will likely generate wrong results for g-Lock (this will be addressed in a later release).
You need to test every kind of movement with different sensibility setting, because its effect are different.

screenshot 1 - main screenshot 2 - settings screenshot 3 - notify options screenshot 4 - events

Initial release, base accelerometer control
Direction movements.

And suggestions are welcome :-)

Guillame Gay - french translation
Herwig Bauerfeind - german translation
Elbert Pol - dutch translation

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