#3520 Searchable Settings (#3683)

* Adding class stubs for settings search, UI elements.

* -  implement searchable settings
- `SettingsController.setupPreferenceScreen` must return a PreferenceScreen

* Remove unneeded SettingsControllerFactory.

* Set query hint, clean up code smell.

* Add search button to MoreController, stop infinite recursion.

* - initialize SearchResultCollection once in Activity.onCreate

* - implement prefernce highlighting after settings search

* - Ensure all Preferences have a key set or else the highlighting effect will have no effect on it.
- remove ExtensionFilterController and SourceFilterController from settingControllersList in SettingsSearchHelper, since those are related to Extensions and not Settings

* Limiting search to settings menu only, localized breadcrumb string, and code cleanup after code review.

* - moved call to SettingsSearchHelper.initPreferenceSearchResultCollection() into SettingsSearchController

* Code review cleanup and refactoring.

* Inlined non-reused key strings.

* Adding more UI polish, add comments for future enhancements.

* - retain search query when navigating *away* from SettingsSearchController
- keep `searchItem` in `expandActionView` state until user goes back (fixes the empty view in `SettingsSearchSearchController` issue)

Co-authored-by: mpm11011 <markuscicero5@gmail.com>
Co-authored-by: lmj0011 <9396189+lmj0011@users.noreply.github.com>

app/build.gradle

@@ -273,6 +273,8 @@ dependencies {
     testImplementation "org.robolectric:shadows-multidex:$robolectric_version"
     testImplementation "org.robolectric:shadows-play-services:$robolectric_version"
 
+    implementation "org.jetbrains.kotlin:kotlin-reflect:$BuildPluginsVersion.KOTLIN"
+
     final coroutines_version = '1.3.9'
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"

app/src/main/java/eu/kanade/tachiyomi/data/preference/PreferencesHelper.kt

@@ -253,6 +253,10 @@ class PreferencesHelper(val context: Context) {
 
     fun enableDoh() = prefs.getBoolean(Keys.enableDoh, false)
 
+    fun lastSearchQuerySearchSettings() = prefs.getString("last_search_query", "")
+    
+    fun lastSearchQuerySearchSettings(query: String) = prefs.edit { putString("last_search_query", query) }
+
     fun filterChapterByRead() = prefs.getInt(Keys.defaultChapterFilterByRead, Manga.SHOW_ALL)
 
     fun filterChapterByDownloaded() = prefs.getInt(Keys.defaultChapterFilterByDownloaded, Manga.SHOW_ALL)

app/src/main/java/eu/kanade/tachiyomi/ui/browse/extension/ExtensionFilterController.kt

@@ -13,7 +13,7 @@ import uy.kohesive.injekt.api.get
 
 class ExtensionFilterController : SettingsController() {
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.label_extensions
 
         val activeLangs = preferences.enabledLanguages().get()

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/SourceFilterController.kt

@@ -24,7 +24,7 @@ class SourceFilterController : SettingsController() {
 
     private val onlineSources by lazy { Injekt.get<SourceManager>().getOnlineSources() }
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.label_sources
 
         // Get the list of active language codes.
@@ -46,7 +46,7 @@ class SourceFilterController : SettingsController() {
 
             // Create a preference group and set initial state and change listener
             switchPreferenceCategory {
-                preferenceScreen.addPreference(this)
+                this@apply.addPreference(this)
                 title = LocaleHelper.getSourceDisplayName(lang, context)
                 isPersistent = false
                 if (lang in activeLangsCodes) {

app/src/main/java/eu/kanade/tachiyomi/ui/more/AboutController.kt

@@ -41,10 +41,11 @@ class AboutController : SettingsController() {
 
     private val isUpdaterEnabled = BuildConfig.INCLUDE_UPDATER
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_about
 
         preference {
+            key = "pref_about_version"
             titleRes = R.string.version
             summary = if (BuildConfig.DEBUG) {
                 "Preview r${BuildConfig.COMMIT_COUNT} (${BuildConfig.COMMIT_SHA})"
@@ -55,17 +56,20 @@ class AboutController : SettingsController() {
             onClick { copyDebugInfo() }
         }
         preference {
+            key = "pref_about_build_time"
             titleRes = R.string.build_time
             summary = getFormattedBuildTime()
         }
         if (isUpdaterEnabled) {
             preference {
+                key = "pref_about_check_for_updates"
                 titleRes = R.string.check_for_updates
 
                 onClick { checkVersion() }
             }
         }
         preference {
+            key = "pref_about_whats_new"
             titleRes = R.string.whats_new
 
             onClick {
@@ -81,6 +85,7 @@ class AboutController : SettingsController() {
         }
         if (BuildConfig.DEBUG) {
             preference {
+                key = "pref_about_notices"
                 titleRes = R.string.notices
 
                 onClick {
@@ -92,6 +97,7 @@ class AboutController : SettingsController() {
 
         preferenceCategory {
             preference {
+                key = "pref_about_website"
                 titleRes = R.string.website
                 val url = "https://tachiyomi.org"
                 summary = url
@@ -101,6 +107,7 @@ class AboutController : SettingsController() {
                 }
             }
             preference {
+                key = "pref_about_discord"
                 title = "Discord"
                 val url = "https://discord.gg/tachiyomi"
                 summary = url
@@ -110,6 +117,7 @@ class AboutController : SettingsController() {
                 }
             }
             preference {
+                key = "pref_about_github"
                 title = "GitHub"
                 val url = "https://github.com/inorichi/tachiyomi"
                 summary = url
@@ -119,6 +127,7 @@ class AboutController : SettingsController() {
                 }
             }
             preference {
+                key = "pref_about_label_extensions"
                 titleRes = R.string.label_extensions
                 val url = "https://github.com/inorichi/tachiyomi-extensions"
                 summary = url
@@ -128,6 +137,7 @@ class AboutController : SettingsController() {
                 }
             }
             preference {
+                key = "pref_about_licenses"
                 titleRes = R.string.licenses
 
                 onClick {

app/src/main/java/eu/kanade/tachiyomi/ui/more/MoreController.kt

@@ -38,7 +38,7 @@ class MoreController :
     private var isDownloading: Boolean = false
     private var downloadQueueSize: Int = 0
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.label_more
 
         val tintColor = context.getResourceColor(R.attr.colorAccent)

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsAdvancedController.kt

@@ -33,7 +33,6 @@ import uy.kohesive.injekt.injectLazy
 import eu.kanade.tachiyomi.data.preference.PreferenceKeys as Keys
 
 class SettingsAdvancedController : SettingsController() {
-
     private val network: NetworkHelper by injectLazy()
 
     private val chapterCache: ChapterCache by injectLazy()
@@ -41,9 +40,8 @@ class SettingsAdvancedController : SettingsController() {
     private val db: DatabaseHelper by injectLazy()
 
     @SuppressLint("BatteryLife")
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_advanced
-
         switchPreference {
             key = "acra.enable"
             titleRes = R.string.pref_enable_acra
@@ -53,6 +51,7 @@ class SettingsAdvancedController : SettingsController() {
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             preference {
+                key = "pref_disable_battery_optimization"
                 titleRes = R.string.pref_disable_battery_optimization
                 summaryRes = R.string.pref_disable_battery_optimization_summary
 
@@ -86,6 +85,7 @@ class SettingsAdvancedController : SettingsController() {
                 onClick { clearChapterCache() }
             }
             preference {
+                key = "pref_clear_database"
                 titleRes = R.string.pref_clear_database
                 summaryRes = R.string.pref_clear_database_summary
 
@@ -101,6 +101,7 @@ class SettingsAdvancedController : SettingsController() {
             titleRes = R.string.label_network
 
             preference {
+                key = "pref_clear_cookies"
                 titleRes = R.string.pref_clear_cookies
 
                 onClick {
@@ -120,11 +121,13 @@ class SettingsAdvancedController : SettingsController() {
             titleRes = R.string.label_library
 
             preference {
+                key = "pref_refresh_library_covers"
                 titleRes = R.string.pref_refresh_library_covers
 
                 onClick { LibraryUpdateService.start(context, target = Target.COVERS) }
             }
             preference {
+                key = "pref_refresh_library_tracking"
                 titleRes = R.string.pref_refresh_library_tracking
                 summaryRes = R.string.pref_refresh_library_tracking_summary
 

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsBackupController.kt

@@ -49,10 +49,11 @@ class SettingsBackupController : SettingsController() {
         requestPermissionsSafe(arrayOf(WRITE_EXTERNAL_STORAGE), 500)
     }
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.backup
 
         preference {
+            key = "pref_create_backup"
             titleRes = R.string.pref_create_backup
             summaryRes = R.string.pref_create_backup_summ
 
@@ -67,6 +68,7 @@ class SettingsBackupController : SettingsController() {
             }
         }
         preference {
+            key = "pref_restore_backup"
             titleRes = R.string.pref_restore_backup
             summaryRes = R.string.pref_restore_backup_summ
 

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsBrowseController.kt

@@ -12,7 +12,7 @@ import eu.kanade.tachiyomi.data.preference.PreferenceKeys as Keys
 
 class SettingsBrowseController : SettingsController() {
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.browse
 
         preferenceCategory {

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsController.kt

@@ -1,6 +1,9 @@
 package eu.kanade.tachiyomi.ui.setting
 
+import android.animation.ArgbEvaluator
+import android.animation.ValueAnimator
 import android.content.Context
+import android.graphics.Color
 import android.os.Bundle
 import android.util.TypedValue
 import android.view.ContextThemeWrapper
@@ -9,12 +12,14 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.app.AppCompatActivity
 import androidx.preference.PreferenceController
+import androidx.preference.PreferenceGroup
 import androidx.preference.PreferenceScreen
 import com.bluelinelabs.conductor.ControllerChangeHandler
 import com.bluelinelabs.conductor.ControllerChangeType
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.preference.PreferencesHelper
 import eu.kanade.tachiyomi.ui.base.controller.BaseController
+import eu.kanade.tachiyomi.util.system.getResourceColor
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
@@ -26,6 +31,7 @@ import uy.kohesive.injekt.api.get
 
 abstract class SettingsController : PreferenceController() {
 
+    var preferenceKey: String? = null
     val preferences: PreferencesHelper = Injekt.get()
     val scope = CoroutineScope(Job() + Dispatchers.Main)
 
@@ -39,6 +45,24 @@ abstract class SettingsController : PreferenceController() {
         return super.onCreateView(inflater, container, savedInstanceState)
     }
 
+    override fun onAttach(view: View) {
+        super.onAttach(view)
+
+        preferenceKey?.let { prefKey ->
+            val adapter = listView.adapter
+            scrollToPreference(prefKey)
+
+            listView.post {
+                if (adapter is PreferenceGroup.PreferencePositionCallback) {
+                    val pos = adapter.getPreferenceAdapterPosition(prefKey)
+                    listView.findViewHolderForAdapterPosition(pos)?.let {
+                        animatePreferenceHighlight(it.itemView)
+                    }
+                }
+            }
+        }
+    }
+
     override fun onDestroyView(view: View) {
         super.onDestroyView(view)
         untilDestroySubscriptions.unsubscribe()
@@ -50,7 +74,7 @@ abstract class SettingsController : PreferenceController() {
         setupPreferenceScreen(screen)
     }
 
-    abstract fun setupPreferenceScreen(screen: PreferenceScreen): Any?
+    abstract fun setupPreferenceScreen(screen: PreferenceScreen): PreferenceScreen
 
     private fun getThemedContext(): Context {
         val tv = TypedValue()
@@ -58,6 +82,17 @@ abstract class SettingsController : PreferenceController() {
         return ContextThemeWrapper(activity, tv.resourceId)
     }
 
+    private fun animatePreferenceHighlight(view: View) {
+        ValueAnimator
+            .ofObject(ArgbEvaluator(), Color.TRANSPARENT, view.context.getResourceColor(R.attr.rippleColor))
+            .apply {
+                duration = 500L
+                repeatCount = 2
+                addUpdateListener { animator -> view.setBackgroundColor(animator.animatedValue as Int) }
+                reverse()
+            }
+    }
+
     open fun getTitle(): String? {
         return preferenceScreen?.title?.toString()
     }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsDownloadController.kt

@@ -40,7 +40,7 @@ class SettingsDownloadController : SettingsController() {
 
     private val db: DatabaseHelper by injectLazy()
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_downloads
 
         preference {

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsGeneralController.kt

@@ -24,7 +24,7 @@ import eu.kanade.tachiyomi.data.preference.PreferenceValues as Values
 
 class SettingsGeneralController : SettingsController() {
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_general
 
         intListPreference {
@@ -47,6 +47,7 @@ class SettingsGeneralController : SettingsController() {
         }
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             preference {
+                key = "pref_manage_notifications"
                 titleRes = R.string.pref_manage_notifications
                 onClick {
                     val intent = Intent(Settings.ACTION_APP_NOTIFICATION_SETTINGS).apply {

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsLibraryController.kt

@@ -40,7 +40,7 @@ class SettingsLibraryController : SettingsController() {
 
     private val db: DatabaseHelper = Injekt.get()
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_library
 
         val dbCategories = db.getCategories().executeAsBlocking()
@@ -50,6 +50,7 @@ class SettingsLibraryController : SettingsController() {
             titleRes = R.string.pref_category_display
 
             preference {
+                key = "pref_library_columns"
                 titleRes = R.string.pref_library_columns
                 onClick {
                     LibraryColumnsDialog().showDialog(router)
@@ -83,6 +84,7 @@ class SettingsLibraryController : SettingsController() {
             titleRes = R.string.pref_category_library_categories
 
             preference {
+                key = "pref_action_edit_categories"
                 titleRes = R.string.action_edit_categories
 
                 val catCount = dbCategories.size

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsMainController.kt

@@ -1,8 +1,13 @@
 package eu.kanade.tachiyomi.ui.setting
 
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import androidx.appcompat.widget.SearchView
 import androidx.preference.PreferenceScreen
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.ui.base.controller.withFadeTransaction
+import eu.kanade.tachiyomi.ui.setting.settingssearch.SettingsSearchController
 import eu.kanade.tachiyomi.util.preference.iconRes
 import eu.kanade.tachiyomi.util.preference.iconTint
 import eu.kanade.tachiyomi.util.preference.onClick
@@ -12,7 +17,7 @@ import eu.kanade.tachiyomi.util.system.getResourceColor
 
 class SettingsMainController : SettingsController() {
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.label_settings
 
         val tintColor = context.getResourceColor(R.attr.colorAccent)
@@ -82,4 +87,29 @@ class SettingsMainController : SettingsController() {
     private fun navigateTo(controller: SettingsController) {
         router.pushController(controller.withFadeTransaction())
     }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        // Inflate menu
+        inflater.inflate(R.menu.settings_main, menu)
+
+        // Initialize search option.
+        val searchItem = menu.findItem(R.id.action_search)
+        val searchView = searchItem.actionView as SearchView
+        searchView.maxWidth = Int.MAX_VALUE
+
+        // Change hint to show global search.
+        searchView.queryHint = applicationContext?.getString(R.string.action_search_settings)
+
+        searchItem.setOnActionExpandListener(object : MenuItem.OnActionExpandListener {
+            override fun onMenuItemActionExpand(item: MenuItem?): Boolean {
+                preferences.lastSearchQuerySearchSettings("") // reset saved search query
+                router.pushController(SettingsSearchController().withFadeTransaction())
+                return true
+            }
+
+            override fun onMenuItemActionCollapse(item: MenuItem?): Boolean {
+                return true
+            }
+        })
+    }
 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsParentalControlsController.kt

@@ -13,7 +13,7 @@ import eu.kanade.tachiyomi.data.preference.PreferenceValues as Values
 
 class SettingsParentalControlsController : SettingsController() {
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_parental_controls
 
         listPreference {

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsReaderController.kt

@@ -19,7 +19,7 @@ import eu.kanade.tachiyomi.data.preference.PreferenceKeys as Keys
 
 class SettingsReaderController : SettingsController() {
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_reader
 
         intListPreference {

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsSecurityController.kt

@@ -14,7 +14,7 @@ import eu.kanade.tachiyomi.data.preference.PreferenceKeys as Keys
 
 class SettingsSecurityController : SettingsController() {
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_security
 
         if (BiometricManager.from(context).canAuthenticate() == BiometricManager.BIOMETRIC_SUCCESS) {

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsTrackingController.kt

@@ -31,7 +31,7 @@ class SettingsTrackingController :
 
     private val trackManager: TrackManager by injectLazy()
 
-    override fun setupPreferenceScreen(screen: PreferenceScreen) = with(screen) {
+    override fun setupPreferenceScreen(screen: PreferenceScreen) = screen.apply {
         titleRes = R.string.pref_category_tracking
 
         switchPreference {

app/src/main/java/eu/kanade/tachiyomi/ui/setting/settingssearch/SettingsSearchAdapter.kt

@@ -0,0 +1,80 @@
+package eu.kanade.tachiyomi.ui.setting.settingssearch
+
+import android.os.Bundle
+import android.os.Parcelable
+import android.util.SparseArray
+import androidx.recyclerview.widget.RecyclerView
+import eu.davidea.flexibleadapter.FlexibleAdapter
+import eu.kanade.tachiyomi.ui.setting.SettingsController
+
+/**
+ * Adapter that holds the search cards.
+ *
+ * @param controller instance of [SettingsSearchController].
+ */
+class SettingsSearchAdapter(val controller: SettingsSearchController) :
+    FlexibleAdapter<SettingsSearchItem>(null, controller, true) {
+
+    val titleClickListener: OnTitleClickListener = controller
+
+    /**
+     * Bundle where the view state of the holders is saved.
+     */
+    private var bundle = Bundle()
+
+    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int, payloads: List<Any?>) {
+        super.onBindViewHolder(holder, position, payloads)
+        restoreHolderState(holder)
+    }
+
+    override fun onViewRecycled(holder: RecyclerView.ViewHolder) {
+        super.onViewRecycled(holder)
+        saveHolderState(holder, bundle)
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        val holdersBundle = Bundle()
+        allBoundViewHolders.forEach { saveHolderState(it, holdersBundle) }
+        outState.putBundle(HOLDER_BUNDLE_KEY, holdersBundle)
+        super.onSaveInstanceState(outState)
+    }
+
+    override fun onRestoreInstanceState(savedInstanceState: Bundle) {
+        super.onRestoreInstanceState(savedInstanceState)
+        bundle = savedInstanceState.getBundle(HOLDER_BUNDLE_KEY)!!
+    }
+
+    /**
+     * Saves the view state of the given holder.
+     *
+     * @param holder The holder to save.
+     * @param outState The bundle where the state is saved.
+     */
+    private fun saveHolderState(holder: RecyclerView.ViewHolder, outState: Bundle) {
+        val key = "holder_${holder.bindingAdapterPosition}"
+        val holderState = SparseArray<Parcelable>()
+        holder.itemView.saveHierarchyState(holderState)
+        outState.putSparseParcelableArray(key, holderState)
+    }
+
+    /**
+     * Restores the view state of the given holder.
+     *
+     * @param holder The holder to restore.
+     */
+    private fun restoreHolderState(holder: RecyclerView.ViewHolder) {
+        val key = "holder_${holder.bindingAdapterPosition}"
+        bundle.getSparseParcelableArray<Parcelable>(key)?.let {
+            holder.itemView.restoreHierarchyState(it)
+            bundle.remove(key)
+        }
+    }
+
+    interface OnTitleClickListener {
+        fun onTitleClick(ctrl: SettingsController)
+    }
+
+    private companion object {
+        const val HOLDER_BUNDLE_KEY = "holder_bundle"
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/setting/settingssearch/SettingsSearchController.kt

@@ -0,0 +1,168 @@
+package eu.kanade.tachiyomi.ui.setting.settingssearch
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
+import androidx.appcompat.widget.SearchView
+import androidx.recyclerview.widget.LinearLayoutManager
+import eu.kanade.tachiyomi.R
+import eu.kanade.tachiyomi.databinding.SettingsSearchControllerBinding
+import eu.kanade.tachiyomi.ui.base.controller.NucleusController
+import eu.kanade.tachiyomi.ui.base.controller.withFadeTransaction
+import eu.kanade.tachiyomi.ui.setting.SettingsController
+
+/**
+ * This controller shows and manages the different search result in settings search.
+ * [SettingsSearchAdapter.OnTitleClickListener] called when preference is clicked in settings search
+ */
+class SettingsSearchController :
+    NucleusController<SettingsSearchControllerBinding, SettingsSearchPresenter>(),
+    SettingsSearchAdapter.OnTitleClickListener {
+
+    /**
+     * Adapter containing search results grouped by lang.
+     */
+    protected var adapter: SettingsSearchAdapter? = null
+    lateinit var searchView: SearchView
+
+    init {
+        setHasOptionsMenu(true)
+    }
+
+    /**
+     * Initiate the view with [R.layout.settings_search_controller].
+     *
+     * @param inflater used to load the layout xml.
+     * @param container containing parent views.
+     * @return inflated view
+     */
+    override fun inflateView(inflater: LayoutInflater, container: ViewGroup): View {
+        binding = SettingsSearchControllerBinding.inflate(inflater)
+        return binding.root
+    }
+
+    override fun getTitle(): String? {
+        return presenter.query
+    }
+
+    /**
+     * Create the [SettingsSearchPresenter] used in controller.
+     *
+     * @return instance of [SettingsSearchPresenter]
+     */
+    override fun createPresenter(): SettingsSearchPresenter {
+        return SettingsSearchPresenter()
+    }
+
+    /**
+     * Adds items to the options menu.
+     *
+     * @param menu menu containing options.
+     * @param inflater used to load the menu xml.
+     */
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        // Inflate menu.
+        inflater.inflate(R.menu.settings_main, menu)
+
+        // Initialize search menu
+        val searchItem = menu.findItem(R.id.action_search)
+        searchView = searchItem.actionView as SearchView
+        searchView.maxWidth = Int.MAX_VALUE
+
+        // Change hint to show "search settings."
+        searchView.queryHint = applicationContext?.getString(R.string.action_search_settings)
+
+        searchItem.expandActionView()
+        setItems(getResultSet())
+
+        searchItem.setOnActionExpandListener(object : MenuItem.OnActionExpandListener {
+            override fun onMenuItemActionExpand(item: MenuItem?): Boolean {
+                return true
+            }
+
+            override fun onMenuItemActionCollapse(item: MenuItem?): Boolean {
+                router.popCurrentController()
+                return false
+            }
+        })
+
+        searchView.setOnQueryTextListener(object : SearchView.OnQueryTextListener {
+            override fun onQueryTextSubmit(query: String?): Boolean {
+                setItems(getResultSet(query))
+                return false
+            }
+
+            override fun onQueryTextChange(newText: String?): Boolean {
+                setItems(getResultSet(newText))
+                return false
+            }
+        })
+
+        searchView.setQuery(presenter.preferences.lastSearchQuerySearchSettings(), true)
+    }
+
+    override fun onViewCreated(view: View) {
+        super.onViewCreated(view)
+
+        adapter = SettingsSearchAdapter(this)
+
+        // Create recycler and set adapter.
+        binding.recycler.layoutManager = LinearLayoutManager(view.context)
+        binding.recycler.adapter = adapter
+
+        // load all search results
+        SettingsSearchHelper.initPreferenceSearchResultCollection(presenter.preferences.context)
+    }
+
+    override fun onDestroyView(view: View) {
+        adapter = null
+        super.onDestroyView(view)
+    }
+
+    override fun onSaveViewState(view: View, outState: Bundle) {
+        super.onSaveViewState(view, outState)
+        adapter?.onSaveInstanceState(outState)
+    }
+
+    override fun onRestoreViewState(view: View, savedViewState: Bundle) {
+        super.onRestoreViewState(view, savedViewState)
+        adapter?.onRestoreInstanceState(savedViewState)
+    }
+
+    /**
+     * returns a list of `SettingsSearchItem` to be shown as search results
+     * Future update: should we add a minimum length to the query before displaying results? Consider other languages.
+     */
+    fun getResultSet(query: String? = null): List<SettingsSearchItem> {
+        if (!query.isNullOrBlank()) {
+            return SettingsSearchHelper.getFilteredResults(query)
+                .map { SettingsSearchItem(it, null) }
+        }
+
+        return mutableListOf()
+    }
+
+    /**
+     * Add search result to adapter.
+     *
+     * @param searchResult result of search.
+     */
+    fun setItems(searchResult: List<SettingsSearchItem>) {
+        adapter?.updateDataSet(searchResult)
+    }
+
+    /**
+     * Opens a catalogue with the given search.
+     */
+    override fun onTitleClick(ctrl: SettingsController) {
+        searchView.query.let {
+            presenter.preferences.lastSearchQuerySearchSettings(it.toString())
+        }
+
+        router.pushController(ctrl.withFadeTransaction())
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/setting/settingssearch/SettingsSearchHelper.kt

@@ -0,0 +1,136 @@
+package eu.kanade.tachiyomi.ui.setting.settingssearch
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.content.res.Resources
+import androidx.preference.Preference
+import androidx.preference.PreferenceCategory
+import androidx.preference.PreferenceGroup
+import androidx.preference.PreferenceManager
+import eu.kanade.tachiyomi.ui.setting.SettingsAdvancedController
+import eu.kanade.tachiyomi.ui.setting.SettingsBackupController
+import eu.kanade.tachiyomi.ui.setting.SettingsBrowseController
+import eu.kanade.tachiyomi.ui.setting.SettingsController
+import eu.kanade.tachiyomi.ui.setting.SettingsDownloadController
+import eu.kanade.tachiyomi.ui.setting.SettingsGeneralController
+import eu.kanade.tachiyomi.ui.setting.SettingsLibraryController
+import eu.kanade.tachiyomi.ui.setting.SettingsParentalControlsController
+import eu.kanade.tachiyomi.ui.setting.SettingsReaderController
+import eu.kanade.tachiyomi.ui.setting.SettingsSecurityController
+import eu.kanade.tachiyomi.ui.setting.SettingsTrackingController
+import eu.kanade.tachiyomi.util.lang.launchNow
+import eu.kanade.tachiyomi.util.system.isLTR
+import kotlin.reflect.KClass
+import kotlin.reflect.full.createInstance
+
+object SettingsSearchHelper {
+    var prefSearchResultList: MutableList<SettingsSearchResult> = mutableListOf()
+        private set
+
+    /**
+     * All subclasses of `SettingsController` should be listed here, in order to have their preferences searchable.
+     */
+    private val settingControllersList: List<KClass<out SettingsController>> = listOf(
+        SettingsAdvancedController::class,
+        SettingsBackupController::class,
+        SettingsBrowseController::class,
+        SettingsDownloadController::class,
+        SettingsGeneralController::class,
+        SettingsLibraryController::class,
+        SettingsParentalControlsController::class,
+        SettingsReaderController::class,
+        SettingsSecurityController::class,
+        SettingsTrackingController::class
+    )
+
+    /**
+     * Must be called to populate `prefSearchResultList`
+     */
+    @SuppressLint("RestrictedApi")
+    fun initPreferenceSearchResultCollection(context: Context) {
+        val preferenceManager = PreferenceManager(context)
+        prefSearchResultList.clear()
+
+        launchNow {
+            settingControllersList.forEach { kClass ->
+                val ctrl = kClass.createInstance()
+                val settingsPrefScreen = ctrl.setupPreferenceScreen(preferenceManager.createPreferenceScreen(context))
+                val prefCount = settingsPrefScreen.preferenceCount
+                for (i in 0 until prefCount) {
+                    val rootPref = settingsPrefScreen.getPreference(i)
+                    if (rootPref.title == null) continue // no title, not a preference. (note: only info notes appear to not have titles)
+                    getSettingSearchResult(ctrl, rootPref, "${settingsPrefScreen.title}")
+                }
+            }
+        }
+    }
+
+    fun getFilteredResults(query: String): List<SettingsSearchResult> {
+        return prefSearchResultList.filter {
+            val inTitle = it.title.contains(query, true)
+            val inSummary = it.summary.contains(query, true)
+            val inBreadcrumb = it.breadcrumb.contains(query, true)
+
+            return@filter inTitle || inSummary || inBreadcrumb
+        }
+    }
+
+    /**
+     * Extracts the data needed from a `Preference` to create a `SettingsSearchResult`, and then adds it to `prefSearchResultList`
+     * Future enhancement: make bold the text matched by the search query.
+     */
+    private fun getSettingSearchResult(ctrl: SettingsController, pref: Preference, breadcrumbs: String = "") {
+        when (pref) {
+            is PreferenceGroup -> {
+                val breadcrumbsStr = addLocalizedBreadcrumb(breadcrumbs, "${pref.title}")
+
+                for (x in 0 until pref.preferenceCount) {
+                    val subPref = pref.getPreference(x)
+                    getSettingSearchResult(ctrl, subPref, breadcrumbsStr) // recursion
+                }
+            }
+            is PreferenceCategory -> {
+                val breadcrumbsStr = addLocalizedBreadcrumb(breadcrumbs, "${pref.title}")
+
+                for (x in 0 until pref.preferenceCount) {
+                    val subPref = pref.getPreference(x)
+                    getSettingSearchResult(ctrl, subPref, breadcrumbsStr) // recursion
+                }
+            }
+            else -> {
+                // Is an actual preference
+                val title = pref.title.toString()
+                val summary = if (pref.summary != null) pref.summary.toString() else ""
+                val breadcrumbsStr = addLocalizedBreadcrumb(breadcrumbs, "${pref.title}")
+
+                prefSearchResultList.add(
+                    SettingsSearchResult(
+                        key = pref.key,
+                        title = title,
+                        summary = summary,
+                        breadcrumb = breadcrumbsStr,
+                        searchController = ctrl
+                    )
+                )
+            }
+        }
+    }
+
+    private fun addLocalizedBreadcrumb(path: String, node: String): String {
+        return if (Resources.getSystem().isLTR) {
+            // This locale reads left to right.
+            "$path > $node"
+        } else {
+            // This locale reads right to left.
+            "$node < $path"
+        }
+    }
+
+    data class SettingsSearchResult(
+        val key: String?,
+        val title: String,
+        val summary: String,
+        val breadcrumb: String,
+        val searchController: SettingsController
+    )
+}

app/src/main/java/eu/kanade/tachiyomi/ui/setting/settingssearch/SettingsSearchHolder.kt

@@ -0,0 +1,42 @@
+package eu.kanade.tachiyomi.ui.setting.settingssearch
+
+import android.view.View
+import eu.kanade.tachiyomi.ui.base.holder.BaseFlexibleViewHolder
+import kotlin.reflect.full.createInstance
+import kotlinx.android.synthetic.main.settings_search_controller_card.search_result_pref_breadcrumb
+import kotlinx.android.synthetic.main.settings_search_controller_card.search_result_pref_summary
+import kotlinx.android.synthetic.main.settings_search_controller_card.search_result_pref_title
+import kotlinx.android.synthetic.main.settings_search_controller_card.title_wrapper
+
+/**
+ * Holder that binds the [SettingsSearchItem] containing catalogue cards.
+ *
+ * @param view view of [SettingsSearchItem]
+ * @param adapter instance of [SettingsSearchAdapter]
+ */
+class SettingsSearchHolder(view: View, val adapter: SettingsSearchAdapter) :
+    BaseFlexibleViewHolder(view, adapter) {
+
+    init {
+        title_wrapper.setOnClickListener {
+            adapter.getItem(bindingAdapterPosition)?.let {
+                val ctrl = it.settingsSearchResult.searchController::class.createInstance()
+                ctrl.preferenceKey = it.settingsSearchResult.key
+
+                // must pass a new Controller instance to avoid this error https://github.com/bluelinelabs/Conductor/issues/446
+                adapter.titleClickListener.onTitleClick(ctrl)
+            }
+        }
+    }
+
+    /**
+     * Show the loading of source search result.
+     *
+     * @param item item of card.
+     */
+    fun bind(item: SettingsSearchItem) {
+        search_result_pref_title.text = item.settingsSearchResult.title
+        search_result_pref_summary.text = item.settingsSearchResult.summary
+        search_result_pref_breadcrumb.text = item.settingsSearchResult.breadcrumb
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/setting/settingssearch/SettingsSearchItem.kt

@@ -0,0 +1,51 @@
+package eu.kanade.tachiyomi.ui.setting.settingssearch
+
+import android.view.View
+import androidx.recyclerview.widget.RecyclerView
+import eu.davidea.flexibleadapter.FlexibleAdapter
+import eu.davidea.flexibleadapter.items.AbstractFlexibleItem
+import eu.davidea.flexibleadapter.items.IFlexible
+import eu.kanade.tachiyomi.R
+
+/**
+ * Item that contains search result information.
+ *
+ * @param pref the source for the search results.
+ * @param results the search results.
+ */
+class SettingsSearchItem(val settingsSearchResult: SettingsSearchHelper.SettingsSearchResult, val results: List<SettingsSearchItem>?) :
+    AbstractFlexibleItem<SettingsSearchHolder>() {
+
+    override fun getLayoutRes(): Int {
+        return R.layout.settings_search_controller_card
+    }
+
+    /**
+     * Create view holder (see [SettingsSearchAdapter].
+     *
+     * @return holder of view.
+     */
+    override fun createViewHolder(view: View, adapter: FlexibleAdapter<IFlexible<RecyclerView.ViewHolder>>): SettingsSearchHolder {
+        return SettingsSearchHolder(view, adapter as SettingsSearchAdapter)
+    }
+
+    override fun bindViewHolder(
+        adapter: FlexibleAdapter<IFlexible<RecyclerView.ViewHolder>>,
+        holder: SettingsSearchHolder,
+        position: Int,
+        payloads: List<Any?>?
+    ) {
+        holder.bind(this)
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (other is SettingsSearchItem) {
+            return settingsSearchResult == settingsSearchResult
+        }
+        return false
+    }
+
+    override fun hashCode(): Int {
+        return settingsSearchResult.hashCode()
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/setting/settingssearch/SettingsSearchPresenter.kt

@@ -0,0 +1,32 @@
+package eu.kanade.tachiyomi.ui.setting.settingssearch
+
+import android.os.Bundle
+import eu.kanade.tachiyomi.data.preference.PreferencesHelper
+import eu.kanade.tachiyomi.ui.base.presenter.BasePresenter
+import uy.kohesive.injekt.Injekt
+import uy.kohesive.injekt.api.get
+
+/**
+ * Presenter of [SettingsSearchController]
+ * Function calls should be done from here. UI calls should be done from the controller.
+ */
+open class SettingsSearchPresenter : BasePresenter<SettingsSearchController>() {
+
+    /**
+     * Query from the view.
+     */
+    var query = ""
+        private set
+
+    val preferences: PreferencesHelper = Injekt.get()
+
+    override fun onCreate(savedState: Bundle?) {
+        super.onCreate(savedState)
+        query = savedState?.getString(SettingsSearchPresenter::query.name) ?: "" // TODO - Some way to restore previous query?
+    }
+
+    override fun onSave(state: Bundle) {
+        state.putString(SettingsSearchPresenter::query.name, query)
+        super.onSave(state)
+    }
+}

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

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content">
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/recycler"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:clipToPadding="false"
+        android:paddingTop="4dp"
+        android:paddingBottom="4dp"
+        tools:listitem="@layout/settings_search_controller_card" />
+
+    <FrameLayout
+        android:id="@+id/progress"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:visibility="gone">
+
+        <FrameLayout
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:background="?attr/colorSurface"
+            android:alpha="0.75" />
+
+        <ProgressBar
+            style="?android:attr/progressBarStyleLarge"
+            android:layout_width="wrap_content"
+            android:layout_height="match_parent"
+            android:layout_gravity="center" />
+
+    </FrameLayout>
+
+</FrameLayout>

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

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/title_wrapper"
+    android:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:layout_marginStart="48dp"
+    android:layout_marginTop="16dp"
+    android:layout_marginBottom="16dp"
+    android:background="?attr/selectableItemBackground">
+
+    <TextView
+        android:id="@+id/search_result_pref_title"
+        style="@style/TextAppearance.Regular.SubHeading"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        tools:text="Title" />
+
+    <TextView
+        android:id="@+id/search_result_pref_summary"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/search_result_pref_title"
+        tools:text="Summary" />
+
+    <TextView
+        android:id="@+id/search_result_pref_breadcrumb"
+        style="@style/TextAppearance.Regular.Caption"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:ellipsize="end"
+        android:maxLines="1"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/search_result_pref_summary"
+        tools:text="Location" />
+</androidx.constraintlayout.widget.ConstraintLayout>
+

app/src/main/res/menu/settings_main.xml

@@ -0,0 +1,12 @@
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <item
+        android:id="@+id/action_search"
+        android:icon="@drawable/ic_search_24dp"
+        android:title="@string/action_search"
+        app:actionViewClass="androidx.appcompat.widget.SearchView"
+        app:iconTint="?attr/colorOnPrimary"
+        app:showAsAction="collapseActionView|ifRoom" />
+
+</menu>

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

@@ -44,6 +44,7 @@
     <string name="action_sort_latest_chapter">Latest chapter</string>
     <string name="action_sort_date_added">Date added</string>
     <string name="action_search">Search</string>
+    <string name="action_search_settings">Search settings</string>
     <string name="action_global_search">Global search</string>
     <string name="action_select_all">Select all</string>
     <string name="action_select_inverse">Select inverse</string>
@@ -411,6 +412,7 @@
     <string name="licenses">Open source licenses</string>
     <string name="check_for_updates">Check for updates</string>
     <string name="updated_version">Updated to v%1$s</string>
+    <string name="about_resources">Resources</string>
 
     <!-- ACRA -->
     <string name="pref_enable_acra">Send crash reports</string>