Refrain your device from sleeping

How to refrain your device from sleeping with App Inventor

Note: with the extension feature, this workaround is now obsolete. Thank you MIT!
Now you can use my Tools Extension and its KeepScreenOn method instead.

As we know, after a certain time the Android device goes inactive. And if the device is sleeping, for example a countdown ends without alarm ... There is no perfect solution with App Inventor to refrain the device from sleeping, because all solutions will drain the battery of your device! Please use these workarounds wisely!

There are the following possibilities:

• Use SL4A to acquire a partial wake lock and release it later again. You will need SL4A installed on the device. See my App Inventor Classic example here.
• >Use a timer together with an empty notifier, thank you Piotr for finding this out! See my snippet how this works here.
• Use a videoplayer continuously playing an invisible video. Thank you Omar for finding it out! See the countdown example below how this works.

Description:
Include a videoplayer component width x height = 1x1, the videoplayer component must be visible on the screen. Upload a small dummy video. Start the video. In the video completed event start it again (or under some condition desired). By playing the video the application is running without sleep. It fades out the screen, then black, but the application still is running.

Note:
This does not work for all components, but it works fine with the Player component.

Thank you freesfx.co.uk for the car alarm sound.
You might be interested in the simplified countdown example for App Inventor 2 provided by richard.

Screenshots

App Inventor blocks

These are the blocks used for the "wake lock"


Further blocks used

Test

Tested successfully on Nexus 5 running Android 5.1.

Download

Download aia file for App Inventor

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This work by Pura Vida Apps is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License
with attribution (name=Pura Vida Apps and link to the source site) required.