image: differentiate different parent songs

Differentiate parents based on their song composition.

This way, it's less likely for an artist/genre/playlist image to get
"stuck" after a library change.

app/src/main/java/org/oxycblt/auxio/image/extractor/Components.kt

@@ -35,20 +35,13 @@ import okio.source
 import org.oxycblt.auxio.list.Sort
 import org.oxycblt.auxio.music.*
 
-/**
- * A [Keyer] implementation for [Music] data.
- *
- * @author Alexander Capehart (OxygenCobalt)
- */
-class MusicKeyer : Keyer<Music> {
-    // TODO: Include hashcode of child songs for parents
-    override fun key(data: Music, options: Options) =
-        if (data is Song) {
-            // Group up song covers with album covers for better caching
-            data.album.uid.toString()
-        } else {
-            data.uid.toString()
+class SongKeyer @Inject constructor() : Keyer<Song> {
+    override fun key(data: Song, options: Options) =
+        "${data.album.uid}${data.album.songs.hashCode()}"
 }
+
+class ParentKeyer @Inject constructor() : Keyer<MusicParent> {
+    override fun key(data: MusicParent, options: Options) = "${data.uid}${data.songs.hashCode()}"
 }
 
 /**

app/src/main/java/org/oxycblt/auxio/image/extractor/ExtractorModule.kt

@@ -35,6 +35,8 @@ class ExtractorModule {
     @Provides
     fun imageLoader(
         @ApplicationContext context: Context,
+        songKeyer: SongKeyer,
+        parentKeyer: ParentKeyer,
         songFactory: AlbumCoverFetcher.SongFactory,
         albumFactory: AlbumCoverFetcher.AlbumFactory,
         artistFactory: ArtistImageFetcher.Factory,
@@ -44,7 +46,8 @@ class ExtractorModule {
         ImageLoader.Builder(context)
             .components {
                 // Add fetchers for Music components to make them usable with ImageRequest
-                add(MusicKeyer())
+                add(songKeyer)
+                add(parentKeyer)
                 add(songFactory)
                 add(albumFactory)
                 add(artistFactory)