replace fake folder hiding with .nomedia check

app/src/main/kotlin/com/simplemobiletools/gallery/activities/MediaActivity.kt

@@ -94,7 +94,7 @@ class MediaActivity : SimpleActivity(), MediaAdapter.MediaOperationsListener {
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         menuInflater.inflate(R.menu.menu_media, menu)
 
-        val isFolderHidden = config.getIsFolderHidden(mPath)
+        val isFolderHidden = File(mPath).containsNoMedia()
         menu.apply {
             findItem(R.id.hide_folder).isVisible = !isFolderHidden && !mShowAll
             findItem(R.id.unhide_folder).isVisible = isFolderHidden && !mShowAll
@@ -147,8 +147,6 @@ class MediaActivity : SimpleActivity(), MediaAdapter.MediaOperationsListener {
     }
 
     private fun hideFolder() {
-        config.addHiddenFolder(mPath)
-
         if (!config.showHiddenFolders)
             finish()
         else
@@ -156,7 +154,6 @@ class MediaActivity : SimpleActivity(), MediaAdapter.MediaOperationsListener {
     }
 
     private fun unhideFolder() {
-        config.removeHiddenFolder(mPath)
         invalidateOptionsMenu()
     }
 

app/src/main/kotlin/com/simplemobiletools/gallery/adapters/DirectoryAdapter.kt

@@ -24,6 +24,7 @@ import com.simplemobiletools.gallery.activities.SimpleActivity
 import com.simplemobiletools.gallery.dialogs.CopyDialog
 import com.simplemobiletools.gallery.dialogs.RenameDirectoryDialog
 import com.simplemobiletools.gallery.extensions.config
+import com.simplemobiletools.gallery.extensions.containsNoMedia
 import com.simplemobiletools.gallery.extensions.createSelector
 import com.simplemobiletools.gallery.models.Directory
 import kotlinx.android.synthetic.main.directory_item.view.*
@@ -114,7 +115,7 @@ class DirectoryAdapter(val activity: SimpleActivity, val dirs: MutableList<Direc
             var hiddenCnt = 0
             var unhiddenCnt = 0
             positions.map { dirs[it].path }.forEach {
-                if (config.getIsFolderHidden(it))
+                if (File(it).containsNoMedia())
                     hiddenCnt++
                 else
                     unhiddenCnt++
@@ -171,11 +172,6 @@ class DirectoryAdapter(val activity: SimpleActivity, val dirs: MutableList<Direc
     }
 
     private fun toggleFoldersVisibility(hide: Boolean) {
-        if (hide)
-            config.addHiddenFolders(getSelectedPaths())
-        else
-            config.removeHiddenFolders(getSelectedPaths())
-
         listener?.refreshItems()
         actMode?.finish()
     }

app/src/main/kotlin/com/simplemobiletools/gallery/asynctasks/GetDirectoriesAsynctask.kt

@@ -7,6 +7,7 @@ import com.simplemobiletools.commons.extensions.isImageFast
 import com.simplemobiletools.commons.extensions.isVideoFast
 import com.simplemobiletools.gallery.R
 import com.simplemobiletools.gallery.extensions.config
+import com.simplemobiletools.gallery.extensions.containsNoMedia
 import com.simplemobiletools.gallery.extensions.getHumanizedFilename
 import com.simplemobiletools.gallery.extensions.getParents
 import com.simplemobiletools.gallery.helpers.IMAGES
@@ -65,7 +66,7 @@ class GetDirectoriesAsynctask(val context: Context, val isPickVideo: Boolean, va
                 directory.addSize(size)
             } else {
                 var dirName = context.getHumanizedFilename(parentDir)
-                if (config.getIsFolderHidden(parentDir)) {
+                if (File(parentDir).containsNoMedia()) {
                     dirName += " ${context.resources.getString(R.string.hidden)}"
                 }
 

app/src/main/kotlin/com/simplemobiletools/gallery/extensions/context.kt

@@ -97,17 +97,10 @@ fun Context.getArgs(isPickImage: Boolean, isPickVideo: Boolean): Array<String> {
 
 fun Context.filterDirectories(dirs: ArrayList<String>) {
     if (!config.showHiddenFolders) {
-        removeHiddenFolders(dirs)
         removeNoMediaFolders(dirs)
     }
 }
 
-fun Context.removeHiddenFolders(paths: MutableList<String>) {
-    val hiddenPaths = config.hiddenFolders
-    val ignorePaths = paths.filter { hiddenPaths.contains(it) }
-    paths.removeAll(ignorePaths)
-}
-
 private fun removeNoMediaFolders(paths: MutableList<String>) {
     val ignorePaths = ArrayList<String>()
     for (path in paths) {

app/src/main/kotlin/com/simplemobiletools/gallery/extensions/file.kt

@@ -1,6 +1,7 @@
 package com.simplemobiletools.gallery.extensions
 
 import android.graphics.Bitmap
+import com.simplemobiletools.gallery.helpers.NOMEDIA
 import java.io.File
 
 fun File.getCompressionFormat(): Bitmap.CompressFormat {
@@ -10,3 +11,5 @@ fun File.getCompressionFormat(): Bitmap.CompressFormat {
         else -> Bitmap.CompressFormat.JPEG
     }
 }
+
+fun File.containsNoMedia() = isDirectory && File(this, NOMEDIA).exists()

app/src/main/kotlin/com/simplemobiletools/gallery/helpers/Config.kt

@@ -46,38 +46,12 @@ class Config(context: Context) : BaseConfig(context) {
         pinnedFolders = currPinnedFolders
     }
 
-    fun addHiddenFolder(path: String) {
-        addHiddenFolders(HashSet<String>(Arrays.asList(path)))
-    }
-
-    fun addHiddenFolders(paths: Set<String>) {
-        val currHiddenFolders = HashSet<String>(hiddenFolders)
-        currHiddenFolders.addAll(paths)
-        hiddenFolders = currHiddenFolders
-    }
-
-    fun removeHiddenFolder(path: String) {
-        removeHiddenFolders(HashSet<String>(Arrays.asList(path)))
-    }
-
-    fun removeHiddenFolders(paths: Set<String>) {
-        val currHiddenFolders = HashSet<String>(hiddenFolders)
-        currHiddenFolders.removeAll(paths)
-        hiddenFolders = currHiddenFolders
-    }
-
-    fun getIsFolderHidden(path: String) = hiddenFolders.contains(path)
-
     fun saveFolderMedia(path: String, json: String) {
         prefs.edit().putString(SAVE_FOLDER_PREFIX + path, json).apply()
     }
 
     fun loadFolderMedia(path: String) = prefs.getString(SAVE_FOLDER_PREFIX + path, "")
 
-    var hiddenFolders: MutableSet<String>
-        get() = prefs.getStringSet(HIDDEN_FOLDERS, HashSet<String>())
-        set(hiddenFolders) = prefs.edit().remove(HIDDEN_FOLDERS).putStringSet(HIDDEN_FOLDERS, hiddenFolders).apply()
-
     var autoplayVideos: Boolean
         get() = prefs.getBoolean(AUTOPLAY_VIDEOS, false)
         set(autoplay) = prefs.edit().putBoolean(AUTOPLAY_VIDEOS, autoplay).apply()

app/src/main/kotlin/com/simplemobiletools/gallery/helpers/Constants.kt

@@ -4,7 +4,6 @@ package com.simplemobiletools.gallery.helpers
 val IS_SAME_SORTING = "is_same_sorting"
 val SORT_ORDER = "sort_order"
 val DIRECTORY_SORT_ORDER = "directory_sort_order"
-val HIDDEN_FOLDERS = "hidden_folders"
 val SHOW_HIDDEN_FOLDERS = "show_hidden_folders"
 val AUTOPLAY_VIDEOS = "autoplay_videos"
 val LOOP_VIDEOS = "loop_videos"
@@ -16,6 +15,8 @@ val SHOW_ALL = "show_all"   // display images and videos from all folders togeth
 val SHOW_MEDIA = "show_media"
 val SAVE_FOLDER_PREFIX = "folder_"
 
+val NOMEDIA = ".nomedia"
+
 // sorting
 val SORT_BY_NAME = 1
 val SORT_BY_DATE_MODIFIED = 2