add the exclusion functionality

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

@@ -179,7 +179,8 @@ class MediaActivity : SimpleActivity(), MediaAdapter.MediaOperationsListener {
     }
 
     private fun excludeFolder() {
-
+        config.addExcludedFolder(mPath)
+        finish()
     }
 
     private fun deleteDirectoryIfEmpty() {

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

@@ -197,7 +197,9 @@ class DirectoryAdapter(val activity: SimpleActivity, val dirs: MutableList<Direc
     }
 
     private fun excludeFolder() {
-
+        activity.config.addExcludedFolders(getSelectedPaths())
+        listener?.refreshItems()
+        actMode?.finish()
     }
 
     private fun noMediaHandled() {

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

@@ -23,6 +23,7 @@ class GetDirectoriesAsynctask(val context: Context, val isPickVideo: Boolean, va
         val showMedia = config.showMedia
         val fileSorting = config.fileSorting
         val parents = context.getParents()
+        removeExcludedFolders(parents)
 
         parents.forEach {
             val filenames = File(it).list()
@@ -92,6 +93,12 @@ class GetDirectoriesAsynctask(val context: Context, val isPickVideo: Boolean, va
         return directories
     }
 
+    private fun removeExcludedFolders(paths: MutableList<String>) {
+        val excludedPaths = config.excludedFolders
+        val ignorePaths = paths.filter { excludedPaths.contains(it) }
+        paths.removeAll(ignorePaths)
+    }
+
     private fun movePinnedToFront(dirs: ArrayList<Directory>): ArrayList<Directory> {
         val foundFolders = ArrayList<Directory>()
         val pinnedFolders = config.pinnedFolders

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

@@ -54,6 +54,20 @@ class Config(context: Context) : BaseConfig(context) {
         pinnedFolders = currPinnedFolders
     }
 
+    fun addExcludedFolder(path: String) {
+        addExcludedFolders(HashSet<String>(Arrays.asList(path)))
+    }
+
+    fun addExcludedFolders(paths: Set<String>) {
+        val currExcludedFolders = HashSet<String>(excludedFolders)
+        currExcludedFolders.addAll(paths)
+        excludedFolders = currExcludedFolders
+    }
+
+    var excludedFolders: MutableSet<String>
+        get() = prefs.getStringSet(EXCLUDED_FOLDERS, HashSet<String>())
+        set(excludedFolders) = prefs.edit().remove(EXCLUDED_FOLDERS).putStringSet(EXCLUDED_FOLDERS, excludedFolders).apply()
+
     fun saveFolderMedia(path: String, json: String) {
         prefs.edit().putString(SAVE_FOLDER_PREFIX + path, json).apply()
     }

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

@@ -16,6 +16,7 @@ val SHOW_MEDIA = "show_media"
 val SAVE_FOLDER_PREFIX = "folder_"
 val HIDE_FOLDER_TOOLTIP_SHOWN = "hide_folder_tooltip_shown"
 val EXCLUDE_FOLDER_TOOLTIP_SHOWN = "exclude_folder_tooltip_shown"
+val EXCLUDED_FOLDERS = "excluded_folders"
 
 val NOMEDIA = ".nomedia"