implement #93 - treat back button as a gesture

app/src/main/java/de/jrpie/android/launcher/actions/Action.kt

@@ -21,6 +21,9 @@ sealed interface Action {
     fun getIcon(context: Context): Drawable?
     fun isAvailable(context: Context): Boolean
 
+    // Can the action be used to reach µLauncher settings?
+    fun canReachSettings(): Boolean
+
 
     fun bindToGesture(prefEditor: Editor, id: String) {
         prefEditor.putString(id, Json.encodeToString(this))
@@ -50,7 +53,10 @@ sealed interface Action {
                     .map { Pair(it, Json.decodeFromString<Action>(it)) }
                     .firstOrNull { it.second.isAvailable(context) }
                     ?.apply {
-                        boundActions.add(first)
+                        // allow to bind CHOOSE to multiple gestures
+                        if (second != LauncherAction.CHOOSE) {
+                            boundActions.add(first)
+                        }
                         second.bindToGesture(editor, gesture.id)
                     }
             }

app/src/main/java/de/jrpie/android/launcher/actions/AppAction.kt

@@ -74,4 +74,8 @@ class AppAction(val app: AppInfo) : Action {
         // check if app is installed
         return DetailedAppInfo.fromAppInfo(app, context) != null
     }
+
+    override fun canReachSettings(): Boolean {
+        return false
+    }
 }

app/src/main/java/de/jrpie/android/launcher/actions/Gesture.kt

@@ -168,6 +168,12 @@ enum class Gesture(
         R.string.settings_gesture_description_double_right,
         R.array.default_double_right,
         R.anim.left_right
+    ),
+    BACK(
+        "action.back",
+        R.string.settings_gesture_back,
+        R.string.settings_gesture_description_back,
+        R.array.default_up
     );
 
     enum class Edge {

app/src/main/java/de/jrpie/android/launcher/actions/LauncherAction.kt

@@ -13,6 +13,7 @@ import android.os.UserManager
 import android.provider.Settings
 import android.view.KeyEvent
 import android.widget.Toast
+import androidx.appcompat.widget.AppCompatDrawableManager
 import de.jrpie.android.launcher.Application
 import de.jrpie.android.launcher.R
 import de.jrpie.android.launcher.apps.AppFilter
@@ -40,25 +41,29 @@ enum class LauncherAction(
     val label: Int,
     val icon: Int,
     val launch: (Context) -> Unit,
-    val available: (Context) -> Boolean = { true }
+    private val canReachSettings: Boolean = false,
+    val available: (Context) -> Boolean = { true },
 ) : Action {
     SETTINGS(
         "settings",
         R.string.list_other_settings,
         R.drawable.baseline_settings_24,
-        ::openSettings
+        ::openSettings,
+        true
     ),
     CHOOSE(
         "choose",
         R.string.list_other_list,
         R.drawable.baseline_menu_24,
-        ::openAppsList
+        ::openAppsList,
+        true
     ),
     CHOOSE_FROM_FAVORITES(
         "choose_from_favorites",
         R.string.list_other_list_favorites,
         R.drawable.baseline_favorite_24,
-        { context -> openAppsList(context, true) }
+        { context -> openAppsList(context, true) },
+        true
     ),
     TOGGLE_PRIVATE_SPACE_LOCK(
         "toggle_private_space_lock",
@@ -127,7 +132,11 @@ enum class LauncherAction(
     }
 
     override fun isAvailable(context: Context): Boolean {
-        return true
+        return this.available(context)
+    }
+
+    override fun canReachSettings(): Boolean {
+        return this.canReachSettings
     }
 
     companion object {

app/src/main/java/de/jrpie/android/launcher/preferences/Preferences.kt

@@ -7,6 +7,7 @@ import de.jrpie.android.launcher.actions.Action
 import de.jrpie.android.launcher.apps.AppInfo
 import de.jrpie.android.launcher.apps.DetailedAppInfo
 import de.jrpie.android.launcher.preferences.legacy.migratePreferencesFromVersion1
+import de.jrpie.android.launcher.preferences.legacy.migratePreferencesFromVersion2
 import de.jrpie.android.launcher.preferences.legacy.migratePreferencesFromVersionUnknown
 import de.jrpie.android.launcher.ui.HomeActivity
 
@@ -14,7 +15,7 @@ import de.jrpie.android.launcher.ui.HomeActivity
  * Increase when breaking changes are introduced and write an appropriate case in
  * `migratePreferencesToNewVersion`
  */
-const val PREFERENCE_VERSION = 2
+const val PREFERENCE_VERSION = 3
 const val UNKNOWN_PREFERENCE_VERSION = -1
 private const val TAG = "Launcher - Preferences"
 
@@ -32,13 +33,16 @@ fun migratePreferencesToNewVersion(context: Context) {
 
             UNKNOWN_PREFERENCE_VERSION -> { /* still using the old preferences file */
                 migratePreferencesFromVersionUnknown(context)
-
+                Log.i(TAG, "migration of preferences  complete (${UNKNOWN_PREFERENCE_VERSION} -> ${PREFERENCE_VERSION}).")
-                Log.i(TAG, "migration of preferences complete.")
             }
 
             1 -> {
                 migratePreferencesFromVersion1()
-                Log.i(TAG, "migration of preferences complete.")
+                Log.i(TAG, "migration of preferences  complete (1 -> ${PREFERENCE_VERSION}).")
+            }
+            2 -> {
+                migratePreferencesFromVersion2()
+                Log.i(TAG, "migration of preferences  complete (2 -> ${PREFERENCE_VERSION}).")
             }
 
             else -> {

app/src/main/java/de/jrpie/android/launcher/preferences/legacy/Version1.kt

@@ -117,11 +117,12 @@ private fun migrateAction(key: String) {
  * (see [PREFERENCE_VERSION])
  */
 fun migratePreferencesFromVersion1() {
-    assert(PREFERENCE_VERSION == 2)
     assert(LauncherPreferences.internal().versionCode() == 1)
     Gesture.entries.forEach { g -> migrateAction(g.id) }
     migrateAppInfoSet(LauncherPreferences.apps().keys().hidden())
     migrateAppInfoSet(LauncherPreferences.apps().keys().favorites())
     migrateAppInfoStringMap(LauncherPreferences.apps().keys().customNames())
     LauncherPreferences.internal().versionCode(2)
+
+    migratePreferencesFromVersion2()
 }

app/src/main/java/de/jrpie/android/launcher/preferences/legacy/Version2.kt

@@ -0,0 +1,20 @@
+package de.jrpie.android.launcher.preferences.legacy
+
+import de.jrpie.android.launcher.actions.Action
+import de.jrpie.android.launcher.actions.Gesture
+import de.jrpie.android.launcher.actions.LauncherAction
+import de.jrpie.android.launcher.preferences.LauncherPreferences
+import de.jrpie.android.launcher.preferences.PREFERENCE_VERSION
+
+
+/**
+ * Migrate preferences from version 2 (used until version 0.0.21) to the current format
+ * (see [PREFERENCE_VERSION])
+ */
+fun migratePreferencesFromVersion2() {
+    assert(PREFERENCE_VERSION == 3)
+    assert(LauncherPreferences.internal().versionCode() == 2)
+    // previously there was no setting for this
+    Action.setActionForGesture(Gesture.BACK, LauncherAction.CHOOSE)
+    LauncherPreferences.internal().versionCode(3)
+}

app/src/main/java/de/jrpie/android/launcher/preferences/legacy/VersionUnknown.kt

@@ -50,7 +50,6 @@ private const val TAG = "Preferences ? -> 1"
  * and a different file was used.
  */
 fun migratePreferencesFromVersionUnknown(context: Context) {
-    assert(PREFERENCE_VERSION == 2)
 
     Log.i(
         TAG,

app/src/main/java/de/jrpie/android/launcher/ui/HomeActivity.kt

@@ -9,6 +9,7 @@ import android.util.DisplayMetrics
 import android.view.GestureDetector
 import android.view.KeyEvent
 import android.view.MotionEvent
+import android.view.View
 import android.view.ViewConfiguration
 import android.window.OnBackInvokedDispatcher
 import androidx.appcompat.app.AppCompatActivity
@@ -54,6 +55,10 @@ class HomeActivity : UIObject, AppCompatActivity(),
             ) {
                 recreate()
             }
+
+            if (prefKey?.startsWith("action.") == true) {
+                updateSettingsFallbackButtonVisibility()
+            }
         }
 
     private var edgeWidth = 0.15f
@@ -80,6 +85,10 @@ class HomeActivity : UIObject, AppCompatActivity(),
                 handleBack()
             }
         }
+        binding.buttonFallbackSettings.setOnClickListener {
+            LauncherAction.SETTINGS.invoke(this)
+        }
+
 
     }
 
@@ -96,6 +105,20 @@ class HomeActivity : UIObject, AppCompatActivity(),
 
     }
 
+    private fun updateSettingsFallbackButtonVisibility() {
+        // If µLauncher settings can not be reached from any action bound to an enabled gesture,
+        // show the fallback button.
+        binding.buttonFallbackSettings.visibility = if (
+            !Gesture.entries.any { g ->
+                g.isEnabled() && Action.forGesture(g)?.canReachSettings() == true
+            }
+        ) {
+            View.VISIBLE
+        } else {
+            View.GONE
+        }
+    }
+
     private fun initClock() {
         val locale = Locale.getDefault()
         val dateVisible = LauncherPreferences.clock().dateVisible()
@@ -152,6 +175,7 @@ class HomeActivity : UIObject, AppCompatActivity(),
         edgeWidth = LauncherPreferences.enabled_gestures().edgeSwipeEdgeWidth() / 100f
 
         initClock()
+        updateSettingsFallbackButtonVisibility()
     }
 
     override fun onDestroy() {
@@ -299,7 +323,7 @@ class HomeActivity : UIObject, AppCompatActivity(),
 
 
     private fun handleBack() {
-        LauncherAction.CHOOSE.launch(this)
+        Gesture.BACK(this)
     }
 
     override fun isHomeScreen(): Boolean {

app/src/main/res/layout/home.xml

@@ -34,4 +34,18 @@
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent" />
 
+    <!-- only shown when µLauncher settings can't be reached by a gesture -->
+    <ImageView
+        android:id="@+id/button_fallback_settings"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:contentDescription="@string/settings"
+        android:visibility="gone"
+        tools:visibility="visible"
+        android:padding="20dp"
+        android:alpha="0.4"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:srcCompat="@drawable/baseline_settings_24"/>
+
 </androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/values/defaults.xml

@@ -3,6 +3,12 @@
 <resources>
     <!-- Default Apps for different actions (button-press, swipes ...) -->
 
+    <!-- Back - Apps list -->
+    <string-array name="default_back">
+        <item>{\"type\": \"action:launcher\", \"value\": \"choose\"}</item> <!-- All Apps -->
+    </string-array>
+
+
     <!-- Swipe up - Apps list -->
     <string-array name="default_up">
         <item>{\"type\": \"action:launcher\", \"value\": \"choose\"}</item> <!-- All Apps -->

app/src/main/res/values/strings.xml

@@ -25,6 +25,8 @@
       - Settings : Apps
       -
       -->
+    <string name="settings_gesture_back">Back</string>
+    <string name="settings_gesture_description_back">Back button / back gesture</string>
     <string name="settings_gesture_up">Up</string>
     <string name="settings_gesture_description_up">Swipe up</string>
     <string name="settings_gesture_double_up">Double Up</string>