Android Wear OS - AmbientModeSupport not working properly in release-mode

Question

I'm using AmbientModeSupport for an Androi Wear OS application: https://developer.android.com/training/wearables/overlays/always-on

Just finished implementing/testing it and everything worked as expected. After app release I noticed that the feature is not working properly when the app is downloaded from Google Play.

I did some extra testing and:

• Everything works if app is installed in debug-mode.
• The Ambient feature is not working well if app is installed in release-mode.

In release-mode, the screen just lowers it's brightness, but there are no changes on the UI (changes performed in onEnterAmbient). The WAKE_LOCK permission is already provided in AndroidManifest:

<uses-permission android:name="android.permission.WAKE_LOCK" />

Any ideas?

---

UPDATE: After I thought I'm completely out of ideas, I realized that my build.gradle has 2 extra things for the release-mode, the proguard and the minify flags:

buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}

It seems that the minifyEnabled caused the problem. I don't know why this behavior occured, but the Ambient Mode is working if I remove the minifyEnabled flag.

Answer 1

Further update:
Turning off minifying of course has the added problem of making your app larger. Here are the settings for Flutter in order to enable minifying in release mode and ALSO allow ambient mode support. This assumes that you are using the standard pub.dev packages 'wear' (and this also includes commands to keep classes needed for the 'wear_os_plugin' and 'wearable_rotary' packages). The 'my-proguard-rules.pro' file that we create/add to the options here will direct the build to NOT remove the kotlin/java classes that we need for support of the ambient mode pub.dev packages.

Changes to buildTypes section of android\app\build.gradle:

 buildTypes {
   release {
     signingConfig signingConfigs.release

     // THIS will make Ambient mode work, but app is larger by around 15 mb..
     //minifyEnabled false
     //shrinkResources false

     minifyEnabled true
     shrinkResources true
     // optimized default: 'proguard-android-optimize.txt'
     //      or unoptimized default: 'proguard-android.txt')
     proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'my-proguard-rules.pro'
   }
 }

and in the file new file you will create in `android\app\my-proguard-rules.pro' :

# Flutter
-keep class io.flutter.app.** { *; }
-keep class io.flutter.plugin.** { *; }
-keep class io.flutter.util.** { *; }
-keep class io.flutter.view.** { *; }
-keep class io.flutter.** { *; }
-keep class io.flutter.plugins.** { *; }

# Keep all these android wear package classes 
# (these are from the packages wear, wear_os_plugin and wearable_rotary)
-keep class com.mjohnsullivan.flutterwear.wear.** { *; }
-keep class org.qooapps.wear_os_plugin.** { *; }
-keep class com.samsung.wearable_rotary.** { *; }

Answer 2

I was having the same issue within my Flutter app, and my build.gradle file did not explicitly have minifyEnabled set to true, but it is the default in release mode. For flutter you also need to set shrinkResources to false (because it is set to true by default also in release mode, and if minifyEnabled is false then shrinkResources must be also be false. Flutter will error on build if you do not do this).

(within android\app\build.grade):

buildTypes {
    release {
        minifyEnabled false                   <<< add these
        shrinkResources false                 <<< lines
    }
}

Once I did this Ambient mode support also worked in release mode.