Add callbacks for if in the background

.travis.yml

@@ -7,11 +7,10 @@ android:
   components:
     - platform-tools
     - tools
-    - build-tools-25.0.2
-    - android-25
-    - extra-android-m2repository
 
 before_script:
-    - chmod +x gradlew
+  # Install SDK license so Android Gradle plugin can install deps.
+  - mkdir "$ANDROID_HOME/licenses" || true
+  - echo "8933bad161af4178b1185d1a37fbf41ea5269c55" > "$ANDROID_HOME/licenses/android-sdk-license"
 
 script: "./gradlew build"

app/build.gradle

@@ -1,13 +1,12 @@
 apply plugin: 'com.android.application'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion "25.0.2"
+    compileSdkVersion 26
 
     defaultConfig {
         applicationId "com.commit451.lifeline.sample"
         minSdkVersion 14
-        targetSdkVersion 25
+        targetSdkVersion 26
         versionCode 1
         versionName "1.0"
     }
@@ -23,7 +22,6 @@ android {
 }
 
 dependencies {
-    compile fileTree(include: ['*.jar'], dir: 'libs')
-    compile 'com.android.support:appcompat-v7:25.2.0'
+    compile 'com.android.support:appcompat-v7:26.1.0'
     compile project(':lifeline')
 }

app/src/main/java/com/commit451/lifeline/sample/App.java

@@ -1,8 +1,10 @@
 package com.commit451.lifeline.sample;
 
 import android.app.Application;
+import android.widget.Toast;
 
 import com.commit451.lifeline.Lifeline;
+import com.commit451.lifeline.OnBackgroundedListener;
 
 /**
  * Here is where you would initialize {@link com.commit451.lifeline.Lifeline}
@@ -13,5 +15,12 @@ public class App extends Application {
     public void onCreate() {
         super.onCreate();
         Lifeline.init(this);
+        Lifeline.register(new OnBackgroundedListener() {
+            @Override
+            public void onBackgrounded() {
+                Toast.makeText(App.this, "On backgrounded", Toast.LENGTH_SHORT)
+                        .show();
+            }
+        });
     }
 }

build.gradle

@@ -1,21 +1,18 @@
-// Top-level build file where you can add configuration options common to all sub-projects/modules.
-
 buildscript {
     repositories {
         jcenter()
+        google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.3.0'
+        classpath 'com.android.tools.build:gradle:3.0.0-beta7'
         classpath 'com.github.dcendents:android-maven-gradle-plugin:1.5'
-
-        // NOTE: Do not place your application dependencies here; they belong
-        // in the individual module build.gradle files
     }
 }
 
 allprojects {
     repositories {
         jcenter()
+        google()
     }
 }
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Wed Mar 08 10:06:00 CST 2017
+#Mon Oct 09 11:06:41 CDT 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip

lifeline/build.gradle

@@ -1,12 +1,11 @@
 apply plugin: 'com.android.library'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion "25.0.2"
+    compileSdkVersion 26
 
     defaultConfig {
         minSdkVersion 14
-        targetSdkVersion 25
+        targetSdkVersion 26
         versionCode 1
         versionName "1.0"
     }
@@ -22,10 +21,7 @@ android {
 }
 
 dependencies {
-    compile fileTree(include: ['*.jar'], dir: 'libs')
-    compile 'com.android.support:support-annotations:25.3.0'
-
-    testCompile 'junit:junit:4.12'
+    compile 'com.android.support:support-annotations:26.1.0'
 }
 
 apply from: 'https://raw.githubusercontent.com/Commit451/gradle-android-javadocs/1.0.0/gradle-android-javadocs.gradle'

lifeline/src/main/java/com/commit451/lifeline/InternalBackgroundListener.java

@@ -0,0 +1,6 @@
+package com.commit451.lifeline;
+
+interface InternalBackgroundListener {
+
+    void onBackgrounded();
+}

lifeline/src/main/java/com/commit451/lifeline/Lifeline.java

@@ -2,17 +2,22 @@
 
 import android.app.Activity;
 import android.app.Application;
+import android.content.ComponentCallbacks2;
+import android.content.res.Configuration;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 
 import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Keeps a pulse on your application
  */
 public class Lifeline {
 
     private static TrackedLifecycleCallbacks lifecycleHandler;
+    private static List<OnBackgroundedListener> onBackgroundedListeners = new ArrayList<>();
 
     /**
      * Hooks your Application up to this Lifeline
@@ -21,6 +26,14 @@ public class Lifeline {
      */
     public static void init(Application application) {
         lifecycleHandler = new TrackedLifecycleCallbacks();
+        application.registerComponentCallbacks(new BackgroundComponentCallbacks2(new InternalBackgroundListener() {
+            @Override
+            public void onBackgrounded() {
+                for (OnBackgroundedListener listener : onBackgroundedListeners) {
+                    listener.onBackgrounded();
+                }
+            }
+        }));
         application.registerActivityLifecycleCallbacks(lifecycleHandler);
     }
 
@@ -96,12 +109,45 @@ public static Activity getCurrentStartedActivity() {
         return null;
     }
 
+    public static void register(OnBackgroundedListener listener) {
+        onBackgroundedListeners.add(listener);
+    }
+
+    public static void unregister(OnBackgroundedListener listener) {
+        onBackgroundedListeners.remove(listener);
+    }
+
     private static void checkInit() {
         if (lifecycleHandler == null) {
             throw new IllegalStateException("You need to first call `init()` on this class before using it");
         }
     }
 
+    private static class BackgroundComponentCallbacks2 implements ComponentCallbacks2 {
+
+        private InternalBackgroundListener listener;
+
+        public BackgroundComponentCallbacks2(InternalBackgroundListener listener) {
+            this.listener = listener;
+        }
+
+        @Override
+        public void onTrimMemory(int level) {
+            if (level == ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN) {
+                // We're in the Background
+                listener.onBackgrounded();
+            }
+        }
+
+        @Override
+        public void onLowMemory() {
+        }
+
+        @Override
+        public void onConfigurationChanged(Configuration newConfig) {
+        }
+    }
+
     /**
      * Inspired by
      * http://stackoverflow.com/questions/3667022/checking-if-an-android-application-is-running-in-the-background/13809991#13809991

lifeline/src/main/java/com/commit451/lifeline/OnBackgroundedListener.java

@@ -0,0 +1,12 @@
+package com.commit451.lifeline;
+
+/**
+ * Listener for when the app is backgrounded
+ */
+public interface OnBackgroundedListener {
+
+    /**
+     * The app has been backgrounded
+     */
+    void onBackgrounded();
+}