Local manga in zip/cbz/folder format (#648)

* add local source

* small fixes

* change Chapter to SChapter and and Manga to SManga in ChapterRecognition.
Use ChapterRecognition.parseChapterNumber() to recognize chapter numbers.

* use thread poll

* update isImage()

* add isImage() function to DiskUtil

* improve cover handling

* Support external SD cards

* use R.string.app_name as root folder name

app/src/main/java/eu/kanade/tachiyomi/data/glide/MangaModelLoader.kt

@@ -1,8 +1,10 @@
 package eu.kanade.tachiyomi.data.glide
 
 import android.content.Context
+import android.net.Uri
 import android.util.LruCache
 import com.bumptech.glide.Glide
+import com.bumptech.glide.Priority
 import com.bumptech.glide.load.data.DataFetcher
 import com.bumptech.glide.load.model.*
 import com.bumptech.glide.load.model.stream.StreamModelLoader
@@ -43,6 +45,12 @@ class MangaModelLoader(context: Context) : StreamModelLoader<Manga> {
     private val baseLoader = Glide.buildModelLoader(GlideUrl::class.java,
             InputStream::class.java, context)
 
+    /**
+     * Base file loader.
+     */
+    private val baseFileLoader = Glide.buildModelLoader(Uri::class.java,
+            InputStream::class.java, context)
+
     /**
      * LRU cache whose key is the thumbnail url of the manga, and the value contains the request url
      * and the file where it should be stored in case the manga is a favorite.
@@ -82,6 +90,18 @@ class MangaModelLoader(context: Context) : StreamModelLoader<Manga> {
             return null
         }
 
+        if (url!!.startsWith("file://")) {
+            val cover = File(url.substring(7))
+            val id = url + File.separator + cover.lastModified()
+            val rf = baseFileLoader.getResourceFetcher(Uri.fromFile(cover), width, height)
+            return object : DataFetcher<InputStream> {
+                override fun cleanup() = rf.cleanup()
+                override fun loadData(priority: Priority?): InputStream = rf.loadData(priority)
+                override fun cancel() = rf.cancel()
+                override fun getId() = id
+            }
+        }
+
         // Obtain the request url and the file for this url from the LRU cache, or calculate it
         // and add them to the cache.
         val (glideUrl, file) = lruCache.get(url) ?: