Add configurable behavior of the back button

This PR allows users to change how the back button functions. Closes #2196

Possible choices are following:

 - **Default** - back button functions how it currently functions (closes the app if there is nowhere to go back to)

 - **Open navigation drawer** - back button always opens the navigation drawer instead of closing the app

 - **Double tap to exit** - like default, but requires two taps to close the app

 - **Confirm to exit** - like default, but prompts user if they really want to exit

1 files changed, 15 insertions, 0 deletions

diff --git a/core/src/main/java/de/danoeh/antennapod/core/preferences/UserPreferences.java b/core/src/main/java/de/danoeh/antennapod/core/preferences/UserPreferences.java
index e6b5f9e1b..c80cfacba 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/preferences/UserPreferences.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/preferences/UserPreferences.java
@@ -52,6 +52,7 @@ public class UserPreferences {
     public static final String PREF_COMPACT_NOTIFICATION_BUTTONS = "prefCompactNotificationButtons";
     public static final String PREF_LOCKSCREEN_BACKGROUND = "prefLockscreenBackground";
     private static final String PREF_SHOW_DOWNLOAD_REPORT = "prefShowDownloadReport";
+    private static final String PREF_BACK_BUTTON_BEHAVIOR = "prefBackButtonBehavior";
 
     // Queue
     private static final String PREF_QUEUE_ADD_TO_FRONT = "prefQueueAddToFront";
@@ -809,4 +810,18 @@ public class UserPreferences {
     public enum VideoBackgroundBehavior {
         STOP, PICTURE_IN_PICTURE, CONTINUE_PLAYING
     }
+
+    public enum BackButtonBehavior {
+        DEFAULT, OPEN_DRAWER, DOUBLE_TAP, SHOW_PROMPT
+    }
+
+    public static BackButtonBehavior getBackButtonBehavior() {
+        switch (prefs.getString(PREF_BACK_BUTTON_BEHAVIOR, "default")) {
+            case "default": return BackButtonBehavior.DEFAULT;
+            case "drawer": return BackButtonBehavior.OPEN_DRAWER;
+            case "doubletap": return BackButtonBehavior.DOUBLE_TAP;
+            case "prompt": return BackButtonBehavior.SHOW_PROMPT;
+            default: return BackButtonBehavior.DEFAULT;
+        }
+    }
 }