I have a service that detects when the display of my Android phone is turned on or off. When turned off, the service calls an activity that uses dispatchKeyEvent to detect when the volume up button has been pressed. Unfortunately, apparently the activity can't do this when the screen is off. (See this post.)
I've noticed, though, that something at some level is detecting that event, since the following LogCat message appears when I press the volume-up button when the screen is off: "CatService: Return current sInstance". The message seems to be device specific, since on a different device something different appears in the log, but I'm really only concerned about the first device.
I've done some research into CatService, but haven't found much and can't figure out how I might be able to use it, or whatever is generating the log message, to detect the volume up button press. I'd appreciate any light that anyone can shed on this.
The only way to keep detecting things like this when the screen is off is to acquire a WakeLock that will allow the screen to turn off, and still let your app function. However, this drains the battery life quite a bit, and should only be used when absolutely necessary.
In this case, you will need a PARTIAL_WAKE_LOCK.
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What I have so far is a Service with a registered BroadcastReceiver for the following actions: ACTION_SCREEN_ON/ACTION_SCREEN_OFF.
So far so good. If the screen goes ON or OFF I get the notification. But this happens for various reasons: user pushes a button (POWER, HOME, etc), battery gets fully charged, incoming call, etc.
What I need is to detect what was the reason for turning the screen ON. And more precisely to detect if it was because of the user pushing power or home button. I've read some opinions that there is no reliable way to do this, but would like to ask again before giving up.
Thanks in advance!
I am aware that this question has been asked already in this site, but I could not find my answer. SO this is what i am trying ot do. My power button in my phone is not working properly. So could is there a way to override my volume up button to unlock my phone.
I am planning to implement broadcast receiver But could not find the appropriate intent-filter. Another alternative that I thought was to run a service when the screen is locked, but I am not quite sure if I can listen to key events.
So if any of the above mentioned is possible, could you hint on how to get it done or suggest another alternative?
No, It do not think so. This can not be done.
There is no broadcast for volume up or down button presently. You can implement a service that will listen for any changes in the volume but it is not recommended to run a service all the time since that consumes both battery and memory.
The only solution that I can think of is using ContentObservers for listening to the changes in the settings such as volume of streams. This answer here will provide you with the code to use ContentObserver to listen for volume up or down. https://stackoverflow.com/a/7017516/1979347
This functionality you speak of has already been done multiple times and can be found on Google Play. However, I'm not sure how they did it, or how much their solution drains the battery.
I just did a test on my G2 (Android 4.2.2), I launched a broadcast monitor, I switched to the homescreen, and I changed the volume from there.
Apparently, it can detect if the volume is turned up only when it changes from silent mode > to Vibration mode > or to Sound mode. Conversely, when pressing the down volume, I think we can detect the change when it goes from the Sound Mode > to Vibration Mode > or to Silent Mode.
This is probably not what you wanted to hear, but I just wanted to confirm what the others were saying. On a non-rooted phone, what they're saying is mostly correct. On a rooted phone however, there are custom ROMs that have solved this issue.
By the way, what brand/model is your phone? On my phone, when the headset gets connected, the phone lights up. So I suppose, one could always do it the way iPhone owners do it for their phones. You'd have to cut the extremity of a head phone jack, coat half of the pin in plastic, and super glue a button on top of it to allow you to easily twist the head.
i am currently collecting information, if it is possible to make some kind of quickdraw-application for emergency purposes; i want to get the device to start a customized camera-intent once some certain key-combo is pressed.
I have check quite some information on the topic already, but it is still not clear to me how doable this whole idea is.
So far i figured, that it is not meant to be by android-design. My first idea was to build some kind of InputService and make it teach the hard power-button to listen for a triple-click. But the Services arent allowed to catch KeyEvents. So, the volume-button is out of the equasion aswell.
Then i came across the idea reacting on the SCREEN ON/OFF event, but 80% of the ppl say that it is not going to work, while 20% state, that they got it. But im not really sure if they really did it.
Last but not least the question, if it is possible to launch this customized-camera-intent/application out of the locked mode.
resumé: i need to check if its possible in general to launch this camera-app (that does some quick fotos for emergency purposes) while phone is in the pocket in lock-mode. Anybody got some opinion for me? thx
The solution is to setup a BroadcastReceiver that is listening for the SCREEN_ON-Event. I did this one inside a backgroundservice that was waiting for at least two SCREEN_ON-Events within a short period of time. (less than two events obviously can't work)...
The Service then dismissed the Keyguard and was able to even pass past password/gesture and run the App. Funny fact: closing the app does pop back to desktop still beeing logged in.
I did this at Android 4.2.. Sources told me that dismissing the keyguard is not working with current Android-versions no more.
For this question I'm going to quote another user who got no response to their question:
I've written an Andoid app that uses the hardware Volume buttons for another purpose.
It works fine if the app is running and visible, but when I turn the
screen off or let it time out, the button clicks don't get into my
handlers.
Does anyone know if there is a way to detect these button clicks when
the screen is off?
Source: AV695's question
I'm working on an app myself that makes use of the volume buttons, but as this user also noted, the normal behavior of checking buttons with onKeyPress stops working once the screen is off. This is because the Activity gets paused on screen off.
Is there a way to keep the activity running while the screen is off, or check for the usage of the volume buttons when the screen is off? I tried using a Service for this before but it's impossible to check for the volume keys like that as noted by Commonsware.
I doubt that this is supported (without resorting to a battery-draining wakelock) at either the platform, kernel, or underlying radio firmware levels without modifications to the last to bring volume presses during sleep to the attention of the kernel.
Within the realm of reasonable system-ROM modifications, a more reasonable one might be to modify an existing open source ROM for the device to insert some custom platform level code into the handling of the power button usually used to wake up the device preparatory to unlocking it - that at least we know does get the attention of the kernel. That code could then inform the user by sound or vibration if there are unacknowledged notifications.
You could optionally wait briefly, check device orientation, or look for another key press to avoid doing this in an annoying way when the user is holding the device outside their pocket and trying to unlock it.
Or you could not use the volume key and just set a timer to wake up every 15 minutes and vibrate if there are unacknowledged notifications, avoiding the need to fumble in ones pockets.
You mention it's a custom request: if implies it's one off or low-volume, another option to consider would be that a few vendors have "bluetooth watches" out with an SDK that lets you push notifications from an android device.
If you can capture the notification when it's generated, you could push it to the user's wrist, and then let the phone go back to sleep.
You cannot intercept the key while your application is in background, but instead of listening to the KeyPress itself. You can register a ContentObserver, as described in this question.
As Chris Stratton mentioned, the only way to keep your App alive is by using battery-draining wake locks.
However, since I found myself in the same situation, I came up with another solution. Unfortunately, you'll need a rooted device as well as the Xposed framework.
With Xposed, which replaces the zygot process so you can hook yourself into any constructor and method of the system, you will be able to catch the raw KeyEvents before the system handles them.
This is done in PhoneWindowManager.interceptKeyBeforeQueueing(). By using a XC_MethodHook, you can use beforeHookedMethod() on the afore mentioned method to catch every hardware button event, even if the device is in deep sleep.
After catching events you are interested in, you can create a temporary wake lock to do your things but don't forget to release the wake lock after you finished your work.
A good example of how to accomplish this is the Xposed Torch Module.
If you, however, rely on a non rooted system, the bad news is that it's simply not possible without draining the battery...
I was also trying to implement volume button press detection in my app and I left that part to be developed later once the core part is done. I was able to detect volume key press while screen is on even when phone is locked, from a background service.
Background Video Recorder 2 (BVR2) (and possible BVR1 also, I did not try) is one of the apps that can detect volume key press even when screen is off. While trying to implement volume key detection while screen is off in my app, I installed BVR2, hoping to find how it works. To my surprise it gave my app the ablity to detect volume keys even when screen is off. My app had a ContentObserver to monitor volume changes, but was not working when screen is off. When BVR2 is active my app also could detect volume key press when screen is off. Still digging.
But BVR2 has its own trigger action, that is to record video, an action you may not want to occur just for the sake of you application detecting volume key presses.
Another app is QuickClick. This app can give your app what it lacks, the power to detect volume key presses even when screen is off, without extra unwanted actions. Just install QuickClick and do not configure any action. Create a ContentObserver to monitor for stream volume changes and you are ready. You app will now be able to detect volume key presses even when screen is off.
Please note that my app runs as a background service.
Both of the apps mentioned above are meant for other uses, but uses volume key detection to perform action. I am in no way connected to any of the apps mentioned.
If these apps, and possibly dozens others, can detect volume key press, it can be done. I request experts to find out how to do it, so that we can implement in our app without relying on another app.
If you find this answer useful, please up-vote.
I am not sure if it is as simple as this but check this android blog:
Allowing applications to play nice(r) with each other: Handling remote control buttons
It explains the usage of a broadcast receiver that receives the up/down volume controls and other music controls.
In summary you should use registerMediaButtonEventReceiver
I'm developing an app which requires the system to get the touch events even after the system goes to sleep mode or after the user locks the screen, I tried searching for a solution but it is hard to find one.
Should I want to set any permissions or is there any inbuilt methods or can I override any methods to perform this functionality.
I'm developing an app which requires the system to get the touch events even after the system goes to sleep mode or after the user locks the screen
Fortunately, this is not possible. Otherwise, the device would not be asleep, and battery life would suffer as a result.
Here is a link that shows how to prevent the phone from sleeping.
If you couple that with, say a black screen to 'pretend' the hone is sleeping but actually running your code. So your code can still intercept touch event
Then you need to install your app as a service and make it start when the device is turned on.
You will not need NDK or rooted device for that (sorry, got a short night :) )