I'm working on an application that continuously logs to a file touch screen information (touch x,y coordinates), I'm using a MotionEvent event to access that information.
I want it to continue working even if the app is closed (home button is pressed).
After some research I found a Service component which can perform long-running operations in the background.
The problem is the MotionEvent is attached to a View and when the app is closed it is not triggering an event anymore.
Is there another way of accessing the screen sensors? or something else I can do?
I'd really appreciate any help I can get!
I want it to continue working even if the app is closed (home button is pressed)
That is not generally possible, for privacy and security reasons. Apps cannot spy on touch input destined for other apps.
You are welcome to explore implementing an accessibility service. Please bear in mind that those APIs are designed for helping people with motor control limitations use their device and its apps. As such, using those APIs for other reasons may not be supported by Google.
Is that possible?
I'm developing a service for disabled people. They can define voice commands and the service can detect the commands and execute them. Like when the user says "scroll down", The service (which is in fact a background process) takes control of screen and scrolls down (regardless of what application is on foreground), or touches a specific position and so forth. I wonder if this is possible in an android device? If not, what about a rooted device? (i.e the service has the root permissions). I know that getting voice input and processing it is possible. My question is about doing actions like touch (Action_Down) or scroll the user interface on behalf of a user.
Note that I don't have access to whatever application is running! In fact my service doesn't know about the application that is running on foreground. It might be a social media app or a messaging app or a game or whatever else! So in fact my service must be capable of defining input events like touch, swipe, scroll etc.
Thanks in advance!
Yes, that is possible.
For example, ListView has two methods for programmatic scroll:
listView.setSelection(id); //For instant scroll
listView.smoothScrollToPosition(id); // For smooth scroll
For an example of how to use voice triggered actions - check this answer out
For an example of how to inject events programmatically - check this link out
I have been trying to design an accessibility application for android for disabled people like that of ios7 switch control point mode. The biggest problem I am facing is how would I make an activity that would appear over all applications and takes switch events and send touch/tap events accordingly to any app over which it is running. I have searched and found that we could have a view that runs on top of other applications using system overlay mode but that does not let me send touch events. Please point me in right direction. Thanks.
You don't want an Activity. You want to develop and AccessibilityService.
http://developer.android.com/training/accessibility/service.html
Accessibility services receive callbacks from the accessibility apis, and are allowed to interact, draw views on top of, and send events to the applications that are running on the device. Once you register yourself as an accessibility service, you have much more power over the way the OS works, than you do within the confines of an application activity. You can even override touch events, and send your own! Though advanced gesture control is lost, as the gestures that you send are within the confines of the accessibility framework.
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
Does anyone knows how to intercept events from other 3rd party Apps, say, games, Maps, etc.
This includes events like motionevents, screen prompts, etc.
We have limited success with capturing touch events via the AccessibilityService, click, longclick, etc. But hitting a blank dealing with motionevents such as gestures or how the users are interacting with the screen.
(we have approval from users to capture such information in a control study)
We believe that if we root the phone (mess with the kernel) we can get such data but this inadvertently void the warranty on the user phone, so is there any other way to obtain such information on the API level?
Many thanks!
In case you are talking about your application gathering information about other applications life time interaction with the user then definitely no.
If this would be possible you could easily write a key logger and steal someones private data.