Detect when an android app goes to the background

[Gurgen]

Hi All,

For the application that I'm working on now, I need somehow to change the app image in background mode when displaying all of the open applications on a mobile device(to hide some sensitive data). I'm looking for a way to detect when an android app goes to the background and come back to foreground.

Before spending time to wrap that functionality with Java FFI capabilities I want to ask if somebody does this or know any way to do this without externals?

Many thanks,
Gurgen

[jacque]

I can't tell you how many times I've needed to know that. No messages are sent when an app goes to the background on Android, there are no suspend messages (and no resume messages either.)

If you get something working I'd be grateful if you could share it.

[Gurgen]

Hi Jacque,

I will let you know about progress.

--
Gurgen

[bogs]

Just curious and thinking out loud as it were, but is this something the focusedObject could be used to test for?

(psuedo code)

Code: Select all

on mouseUp // or android equivalent, I don't code mobile...
   if the focusedObject is not a card or control of this stack then // probably needs a repeat loop to test with...
      objectToReturn = empty 
  end if
  end mouseUp

In other words, if the object being focused on isn't part of your android program, doesn't that mean your program is in the background by default?

Course, this could be faulty logic, just woke up

[Gurgen]

For iOS we have found the way how to check it.

mergNotify - part of mergExt

Code: Select all

on openStack
  mergNotify "UIApplicationWillResignActiveNotification"
  mergNotify "UIApplicationDidBecomeActiveNotification"
end openStack

on UIApplicationWillResignActiveNotification pUserInfo
  // Your code before the app goes to background
end UIApplicationWillResignActiveNotification

on UIApplicationDidBecomeActiveNotification pUserInfo
 // Your code after the app comes back to foreground
end UIApplicationDidBecomeActiveNotification

Hope this is helpful .

--
Gurgen

[jacque]

Thanks, but for now I'm mostly developing for Android. I'm hoping Monte wraps all his many iOS externals so they are compatible with that OS.

[jacque]

Just curious and thinking out loud as it were, but is this something the focusedObject could be used to test for?

(psuedo code)

Code: Select all

on mouseUp // or android equivalent, I don't code mobile...
   if the focusedObject is not a card or control of this stack then // probably needs a repeat loop to test with...
      objectToReturn = empty 
  end if
  end mouseUp

In other words, if the object being focused on isn't part of your android program, doesn't that mean your program is in the background by default?

Course, this could be faulty logic, just woke up

Unfortunately no. When an Android app goes into the background it is inaccessible. The user doesn't see it and can't interact with it until they re-open the app. However it does stay in RAM for a varying amount of time until the OS needs the memory, when it is summarily deleted. There is no notification when that happens. If the app is still in RAM but "closed" there are no messages sent when the user re-opens it because technically it is still open; that is, it doesn't relaunch, it just re-appears.

We could really use "suspend" and "resume" messages so the app knows when to take any necessary actions whenever the app comes to the front. If the OS has deleted the app from RAM then you do get all the usual startup/open-whatever messages. The problem is, when it is idling in the background and the user re-opens it, none of those occur.

[bogs]

Good to know Jacque, thank you for the explanation.

[marksmithhfx]

We could really use "suspend" and "resume" messages so the app knows when to take any necessary actions whenever the app comes to the front. If the OS has deleted the app from RAM then you do get all the usual startup/open-whatever messages. The problem is, when it is idling in the background and the user re-opens it, none of those occur.

Hi Jacques,

Do you know if this suspend-resume messages issue was ever resolved for Android (it's a ways off in my plans, but I will be thinking of migrating my Organize app to Android at some point, and a lot of what I do depends on being able to recognize these transitions).

And while I am thinking of it, do you know if there is iOS notification for when the display is turned off? It doesn't appear to me that that in itself triggers a UIApplicationWillResignActiveNotification message, although it might do so after a certain amount of time elapses (not tested).

Mark

[jacque]

As far as I know, suspend/resume are still not implemented on mobile. Here's the bug report:
https://quality.livecode.com/show_bug.cgi?id=16829

I don't know much about the iOS notification behavior, sorry.

[marksmithhfx]

As far as I know, suspend/resume are still not implemented on mobile. Here's the bug report:
https://quality.livecode.com/show_bug.cgi?id=16829

I don't know much about the iOS notification behavior, sorry.

Ok thanks. Just to add to this discussion, I have been testing more carefully and have discovered that the "suspend" and "resume" messages are being sent when the user turns on/off the iOS display. I'm not sure how I missed observing that, but it works fine. I am seeing no more than a 3-4 second delay between turning off the iPhone display and seeing an update to a dropbox copy of the database. Fast enough for my purposes.

Mark

[jacque]

Interesting, I'll have to try it on Android when I get a chance. The dictionary still does not list mobile in the supported platforms and the bug report hasn't updated, so I didn't even try.

[marksmithhfx]

Interesting, I'll have to try it on Android when I get a chance. The dictionary still does not list mobile in the supported platforms and the bug report hasn't updated, so I didn't even try.

I wonder if Monte would be interested in adding Android to his mergNotify library. I'm using...

Code: Select all

   mergNotify "UIApplicationWillResignActiveNotification" -- enables the app to detect when it is moving into the background
   mergNotify "UIApplicationDidBecomeActiveNotification"  -- and when it is being brought back to the foreground

Mark

[marksmithhfx]

Interesting, I'll have to try it on Android when I get a chance. The dictionary still does not list mobile in the supported platforms and the bug report hasn't updated, so I didn't even try.

Hi Jacque, I think your wish has been answered. Check the release notes for LC 10.0.0 dp6...

Mobile suspend and resume messages
The suspend and resume messages are now supported on mobile platforms.

On iOS, suspend and resume messages are now sent to the current card of the default stack when the application becomes active and inactive respectively, corresponding to the lifecycle events applicationWillResignActive and applicationDidBecomeActive.

On Android, suspend and resume messages are now sent to the current card of the default stack when the application is paused and resumed respectively, corresponding to the Activity's onPause and onResume lifecycle events.