musikr.cover: refactor cover

Instead of using a weird sealed class, instead go for a
Cover/CoverCollection system instead that removes some implicit
design dependence in musikr.

app/src/main/java/org/oxycblt/auxio/image/CoverView.kt

@@ -64,7 +64,7 @@ import org.oxycblt.musikr.Artist
 import org.oxycblt.musikr.Genre
 import org.oxycblt.musikr.Playlist
 import org.oxycblt.musikr.Song
-import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
 
 /**
  * Auxio's extension of [ImageView] that enables cover art loading and playing indicator and
@@ -327,7 +327,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
      */
     fun bind(album: Album) =
         bindImpl(
-            album.cover,
+            album.covers,
             context.getString(R.string.desc_album_cover, album.name),
             R.drawable.ic_album_24)
 
@@ -338,7 +338,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
      */
     fun bind(artist: Artist) =
         bindImpl(
-            artist.cover,
+            artist.covers,
             context.getString(R.string.desc_artist_image, artist.name),
             R.drawable.ic_artist_24)
 
@@ -349,7 +349,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
      */
     fun bind(genre: Genre) =
         bindImpl(
-            genre.cover,
+            genre.covers,
             context.getString(R.string.desc_genre_image, genre.name),
             R.drawable.ic_genre_24)
 
@@ -360,7 +360,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
      */
     fun bind(playlist: Playlist) =
         bindImpl(
-            playlist.cover,
+            playlist.covers,
             context.getString(R.string.desc_playlist_image, playlist.name),
             R.drawable.ic_playlist_24)
 
@@ -372,9 +372,9 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
      * @param errorRes The resource of the error drawable to use if the cover cannot be loaded.
      */
     fun bind(songs: List<Song>, desc: String, @DrawableRes errorRes: Int) =
-        bindImpl(Cover.multi(songs), desc, errorRes)
+        bindImpl(CoverCollection.from(songs.mapNotNull { it.cover }), desc, errorRes)
 
-    private fun bindImpl(cover: Cover?, desc: String, @DrawableRes errorRes: Int) {
+    private fun bindImpl(cover: Any?, desc: String, @DrawableRes errorRes: Int) {
         val request =
             ImageRequest.Builder(context)
                 .data(cover)

app/src/main/java/org/oxycblt/auxio/image/coil/CoilModule.kt

@@ -36,14 +36,17 @@ class CoilModule {
     @Provides
     fun imageLoader(
         @ApplicationContext context: Context,
-        keyer: CoverKeyer,
-        factory: CoverFetcher.Factory
+        coverKeyer: CoverKeyer,
+        coverFactory: CoverFetcher.Factory,
+        coverCollectionKeyer: CoverCollectionKeyer,
+        coverCollectionFactory: CoverCollectionFetcher.Factory
     ) =
         ImageLoader.Builder(context)
             .components {
-                // Add fetchers for Music components to make them usable with ImageRequest
-                add(keyer)
-                add(factory)
+                add(coverKeyer)
+                add(coverFactory)
+                add(coverCollectionKeyer)
+                add(coverCollectionFactory)
             }
             // Use our own crossfade with error drawable support
             .transitionFactory(ErrorCrossfadeTransitionFactory())

app/src/main/java/org/oxycblt/auxio/image/coil/CoverCollectionFetcher.kt

@@ -1,6 +1,6 @@
 /*
- * Copyright (c) 2021 Auxio Project
- * Components.kt is part of Auxio.
+ * Copyright (c) 2024 Auxio Project
+ * CoverCollectionFetcher.kt is part of Auxio.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -31,7 +31,6 @@ import coil3.fetch.FetchResult
 import coil3.fetch.Fetcher
 import coil3.fetch.ImageFetchResult
 import coil3.fetch.SourceFetchResult
-import coil3.key.Keyer
 import coil3.request.Options
 import coil3.size.Dimension
 import coil3.size.Size
@@ -39,36 +38,24 @@ import coil3.size.pxOrElse
 import java.io.InputStream
 import javax.inject.Inject
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.asFlow
+import kotlinx.coroutines.flow.mapNotNull
+import kotlinx.coroutines.flow.take
+import kotlinx.coroutines.flow.toList
 import kotlinx.coroutines.withContext
 import okio.FileSystem
 import okio.buffer
 import okio.source
-import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
 
-class CoverKeyer @Inject constructor() : Keyer<Cover> {
-    override fun key(data: Cover, options: Options) = "${data.id}&${options.size}"
-}
-
-class CoverFetcher
+class CoverCollectionFetcher
 private constructor(
     private val context: Context,
-    private val cover: Cover,
+    private val covers: CoverCollection,
     private val size: Size,
 ) : Fetcher {
     override suspend fun fetch(): FetchResult? {
-        val streams =
-            when (val cover = cover) {
-                is Cover.Single -> listOfNotNull(cover.open())
-                is Cover.Multi ->
-                    buildList {
-                        for (single in cover.all) {
-                            single.open()?.let { add(it) }
-                            if (size == 4) {
-                                break
-                            }
-                        }
-                    }
-            }
+        val streams = covers.covers.asFlow().mapNotNull { it.open() }.take(4).toList()
         // We don't immediately check for mosaic feasibility from album count alone, as that
         // does not factor in InputStreams failing to load. Instead, only check once we
         // definitely have image data to use.
@@ -79,6 +66,7 @@ private constructor(
                 withContext(Dispatchers.IO) { streams.forEach(InputStream::close) }
             }
         }
+
         // Not enough covers for a mosaic, take the first one (if that even exists)
         val first = streams.firstOrNull() ?: return null
 
@@ -146,8 +134,8 @@ private constructor(
         return if (size.mod(2) > 0) size + 1 else size
     }
 
-    class Factory @Inject constructor() : Fetcher.Factory<Cover> {
-        override fun create(data: Cover, options: Options, imageLoader: ImageLoader) =
-            CoverFetcher(options.context, data, options.size)
+    class Factory @Inject constructor() : Fetcher.Factory<CoverCollection> {
+        override fun create(data: CoverCollection, options: Options, imageLoader: ImageLoader) =
+            CoverCollectionFetcher(options.context, data, options.size)
     }
 }

app/src/main/java/org/oxycblt/auxio/image/coil/CoverFetcher.kt

@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2024 Auxio Project
+ * CoverFetcher.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.image.coil
+
+import android.content.Context
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.graphics.Canvas
+import androidx.core.graphics.drawable.toDrawable
+import coil3.ImageLoader
+import coil3.asImage
+import coil3.decode.DataSource
+import coil3.decode.ImageSource
+import coil3.fetch.FetchResult
+import coil3.fetch.Fetcher
+import coil3.fetch.ImageFetchResult
+import coil3.fetch.SourceFetchResult
+import coil3.request.Options
+import coil3.size.Dimension
+import coil3.size.Size
+import coil3.size.pxOrElse
+import java.io.InputStream
+import javax.inject.Inject
+import okio.FileSystem
+import okio.buffer
+import okio.source
+import org.oxycblt.musikr.cover.Cover
+
+class CoverFetcher private constructor(private val context: Context, private val cover: Cover) :
+    Fetcher {
+    override suspend fun fetch(): FetchResult? {
+        val stream = cover.open() ?: return null
+        return SourceFetchResult(
+            source = ImageSource(stream.source().buffer(), FileSystem.SYSTEM, null),
+            mimeType = null,
+            dataSource = DataSource.DISK)
+    }
+
+    /** Derived from phonograph: https://github.com/kabouzeid/Phonograph */
+    private suspend fun createMosaic(streams: List<InputStream>, size: Size): FetchResult {
+        // Use whatever size coil gives us to create the mosaic.
+        val mosaicSize = android.util.Size(size.width.mosaicSize(), size.height.mosaicSize())
+        val mosaicFrameSize =
+            Size(Dimension(mosaicSize.width / 2), Dimension(mosaicSize.height / 2))
+
+        val mosaicBitmap =
+            Bitmap.createBitmap(mosaicSize.width, mosaicSize.height, Bitmap.Config.ARGB_8888)
+        val canvas = Canvas(mosaicBitmap)
+
+        var x = 0
+        var y = 0
+
+        // For each stream, create a bitmap scaled to 1/4th of the mosaics combined size
+        // and place it on a corner of the canvas.
+        for (stream in streams) {
+            if (y == mosaicSize.height) {
+                break
+            }
+
+            // Crop the bitmap down to a square so it leaves no empty space
+            // TODO: Work around this
+            val bitmap =
+                SquareCropTransformation.INSTANCE.transform(
+                    BitmapFactory.decodeStream(stream), mosaicFrameSize)
+            canvas.drawBitmap(bitmap, x.toFloat(), y.toFloat(), null)
+
+            x += bitmap.width
+            if (x == mosaicSize.width) {
+                x = 0
+                y += bitmap.height
+            }
+        }
+
+        // It's way easier to map this into a drawable then try to serialize it into an
+        // BufferedSource. Just make sure we mark it as "sampled" so Coil doesn't try to
+        // load low-res mosaics into high-res ImageViews.
+        return ImageFetchResult(
+            image = mosaicBitmap.toDrawable(context.resources).asImage(),
+            isSampled = true,
+            dataSource = DataSource.DISK)
+    }
+
+    private fun Dimension.mosaicSize(): Int {
+        // Since we want the mosaic to be perfectly divisible into two, we need to round any
+        // odd image sizes upwards to prevent the mosaic creation from failing.
+        val size = pxOrElse { 512 }
+        return if (size.mod(2) > 0) size + 1 else size
+    }
+
+    class Factory @Inject constructor() : Fetcher.Factory<Cover> {
+        override fun create(data: Cover, options: Options, imageLoader: ImageLoader) =
+            CoverFetcher(options.context, data)
+    }
+}

app/src/main/java/org/oxycblt/auxio/image/coil/Keyers.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2021 Auxio Project
+ * Keyers.kt is part of Auxio.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+ 
+package org.oxycblt.auxio.image.coil
+
+import coil3.key.Keyer
+import coil3.request.Options
+import javax.inject.Inject
+import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
+
+class CoverKeyer @Inject constructor() : Keyer<Cover> {
+    override fun key(data: Cover, options: Options) = "${data.id}&${options.size}"
+}
+
+class CoverCollectionKeyer @Inject constructor() : Keyer<CoverCollection> {
+    override fun key(data: CoverCollection, options: Options) =
+        "multi:${data.hashCode()}&${options.size}"
+}

app/src/main/java/org/oxycblt/auxio/music/RevisionedLibrary.kt

@@ -70,7 +70,7 @@ class MutableRevisionedStoredCovers(context: Context, private val revision: UUID
     }
 }
 
-class RevisionedCover(private val revision: UUID, val inner: Cover.Single) : Cover.Single by inner {
+class RevisionedCover(private val revision: UUID, val inner: Cover) : Cover by inner {
     override val id: String
         get() = "${inner.id}@${revision}"
 }

musikr/src/main/java/org/oxycblt/musikr/Music.kt

@@ -26,6 +26,7 @@ import java.util.UUID
 import kotlinx.parcelize.IgnoredOnParcel
 import kotlinx.parcelize.Parcelize
 import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
 import org.oxycblt.musikr.fs.Format
 import org.oxycblt.musikr.fs.Path
 import org.oxycblt.musikr.tag.Date
@@ -276,7 +277,7 @@ interface Song : Music {
     /** The date the audio file was added to the device, as a unix epoch timestamp. */
     val dateAdded: Long
     /** Useful information to quickly obtain the album cover. */
-    val cover: Cover.Single?
+    val cover: Cover?
     /**
      * The parent [Album]. If the metadata did not specify an album, it's parent directory is used
      * instead.
@@ -310,7 +311,7 @@ interface Album : MusicParent {
      */
     val releaseType: ReleaseType
     /** Cover information from album's songs. */
-    val cover: Cover
+    val covers: CoverCollection
     /** The duration of all songs in the album, in milliseconds. */
     val durationMs: Long
     /** The earliest date a song in this album was added, as a unix epoch timestamp. */
@@ -340,7 +341,7 @@ interface Artist : MusicParent {
      */
     val durationMs: Long?
     /** Useful information to quickly obtain a (single) cover for a Genre. */
-    val cover: Cover
+    val covers: CoverCollection
     /** The [Genre]s of this artist. */
     val genres: List<Genre>
 }
@@ -356,7 +357,7 @@ interface Genre : MusicParent {
     /** The total duration of the songs in this genre, in milliseconds. */
     val durationMs: Long
     /** Useful information to quickly obtain a (single) cover for a Genre. */
-    val cover: Cover
+    val covers: CoverCollection
 }
 
 /**
@@ -370,5 +371,5 @@ interface Playlist : MusicParent {
     /** The total duration of the songs in this genre, in milliseconds. */
     val durationMs: Long
     /** Useful information to quickly obtain a (single) cover for a Genre. */
-    val cover: Cover
+    val covers: CoverCollection
 }

musikr/src/main/java/org/oxycblt/musikr/cover/Cover.kt

@@ -19,29 +19,22 @@
 package org.oxycblt.musikr.cover
 
 import java.io.InputStream
-import org.oxycblt.musikr.Song
 
-sealed interface Cover {
+interface Cover {
     val id: String
 
-    interface Single : Cover {
-        suspend fun open(): InputStream?
-    }
-
-    class Multi(val all: List<Single>) : Cover {
-        override val id = "multi@${all.hashCode()}"
-    }
+    suspend fun open(): InputStream?
+}
 
+class CoverCollection private constructor(val covers: List<Cover>) {
     companion object {
-        fun multi(songs: Collection<Song>) = order(songs).run { Multi(this) }
-
-        private fun order(songs: Collection<Song>) =
-            songs
-                .mapNotNull { it.cover }
-                .groupBy { it.id }
-                .entries
-                .sortedByDescending { it.key }
-                .sortedByDescending { it.value.size }
-                .map { it.value.first() }
+        fun from(covers: Collection<Cover>) =
+            CoverCollection(
+                covers
+                    .groupBy { it.id }
+                    .entries
+                    .sortedByDescending { it.key }
+                    .sortedByDescending { it.value.size }
+                    .map { it.value.first() })
     }
 }

musikr/src/main/java/org/oxycblt/musikr/cover/StoredCovers.kt

@@ -21,7 +21,7 @@ package org.oxycblt.musikr.cover
 import android.content.Context
 
 interface StoredCovers {
-    suspend fun obtain(id: String): Cover.Single?
+    suspend fun obtain(id: String): Cover?
 
     companion object {
         fun from(context: Context, path: String, format: CoverFormat): MutableStoredCovers =
@@ -30,7 +30,7 @@ interface StoredCovers {
 }
 
 interface MutableStoredCovers : StoredCovers {
-    suspend fun write(data: ByteArray): Cover.Single?
+    suspend fun write(data: ByteArray): Cover?
 }
 
 private class FileStoredCovers(
@@ -45,6 +45,6 @@ private class FileStoredCovers(
         }
 }
 
-private class FileCover(override val id: String, private val coverFile: CoverFile) : Cover.Single {
+private class FileCover(override val id: String, private val coverFile: CoverFile) : Cover {
     override suspend fun open() = coverFile.open()
 }

musikr/src/main/java/org/oxycblt/musikr/model/AlbumImpl.kt

@@ -22,7 +22,7 @@ import org.oxycblt.musikr.Album
 import org.oxycblt.musikr.Artist
 import org.oxycblt.musikr.Music
 import org.oxycblt.musikr.Song
-import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
 import org.oxycblt.musikr.tag.Date
 import org.oxycblt.musikr.tag.interpret.PreAlbum
 import org.oxycblt.musikr.util.update
@@ -56,7 +56,7 @@ internal class AlbumImpl(private val core: AlbumCore) : Album {
     override val releaseType = preAlbum.releaseType
     override val durationMs = core.songs.sumOf { it.durationMs }
     override val dateAdded = core.songs.minOf { it.dateAdded }
-    override val cover = Cover.multi(core.songs)
+    override val covers = CoverCollection.from(core.songs.mapNotNull { it.cover })
     override val dates: Date.Range? =
         core.songs.mapNotNull { it.date }.ifEmpty { null }?.run { Date.Range(min(), max()) }
 

musikr/src/main/java/org/oxycblt/musikr/model/ArtistImpl.kt

@@ -23,7 +23,7 @@ import org.oxycblt.musikr.Artist
 import org.oxycblt.musikr.Genre
 import org.oxycblt.musikr.Music
 import org.oxycblt.musikr.Song
-import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
 import org.oxycblt.musikr.tag.interpret.PreArtist
 import org.oxycblt.musikr.util.update
 
@@ -55,7 +55,7 @@ internal class ArtistImpl(private val core: ArtistCore) : Artist {
         get() = core.resolveGenres().toList()
 
     override val durationMs = core.songs.sumOf { it.durationMs }
-    override val cover = Cover.multi(core.songs)
+    override val covers = CoverCollection.from(core.songs.mapNotNull { it.cover })
 
     private val hashCode =
         31 * (31 * uid.hashCode() + core.preArtist.hashCode()) * core.songs.hashCode()

musikr/src/main/java/org/oxycblt/musikr/model/GenreImpl.kt

@@ -22,7 +22,7 @@ import org.oxycblt.musikr.Artist
 import org.oxycblt.musikr.Genre
 import org.oxycblt.musikr.Music
 import org.oxycblt.musikr.Song
-import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
 import org.oxycblt.musikr.tag.interpret.PreGenre
 import org.oxycblt.musikr.util.update
 
@@ -44,7 +44,7 @@ internal class GenreImpl(private val core: GenreCore) : Genre {
     override val songs = core.songs
     override val artists = core.artists
     override val durationMs = core.songs.sumOf { it.durationMs }
-    override val cover = Cover.multi(core.songs)
+    override val covers = CoverCollection.from(core.songs.mapNotNull { it.cover })
 
     private val hashCode = 31 * (31 * uid.hashCode() + core.preGenre.hashCode()) + songs.hashCode()
 

musikr/src/main/java/org/oxycblt/musikr/model/PlaylistImpl.kt

@@ -20,7 +20,7 @@ package org.oxycblt.musikr.model
 
 import org.oxycblt.musikr.Playlist
 import org.oxycblt.musikr.Song
-import org.oxycblt.musikr.cover.Cover
+import org.oxycblt.musikr.cover.CoverCollection
 import org.oxycblt.musikr.playlist.interpret.PrePlaylistInfo
 import org.oxycblt.musikr.tag.Name
 
@@ -33,7 +33,7 @@ internal class PlaylistImpl(val core: PlaylistCore) : Playlist {
     override val uid = core.prePlaylist.handle.uid
     override val name: Name.Known = core.prePlaylist.name
     override val durationMs = core.songs.sumOf { it.durationMs }
-    override val cover = Cover.multi(core.songs)
+    override val covers = CoverCollection.from(core.songs.mapNotNull { it.cover })
     override val songs = core.songs
 
     private var hashCode =

musikr/src/main/java/org/oxycblt/musikr/pipeline/ExtractStep.kt

@@ -163,7 +163,7 @@ internal data class RawSong(
     val file: DeviceFile,
     val properties: Properties,
     val tags: ParsedTags,
-    val cover: Cover.Single?
+    val cover: Cover?
 )
 
 internal sealed interface ExtractedMusic {

musikr/src/main/java/org/oxycblt/musikr/tag/interpret/PreMusic.kt

@@ -48,7 +48,7 @@ internal data class PreSong(
     val replayGainAdjustment: ReplayGainAdjustment,
     val lastModified: Long,
     val dateAdded: Long,
-    val cover: Cover.Single?,
+    val cover: Cover?,
     val preAlbum: PreAlbum,
     val preArtists: List<PreArtist>,
     val preGenres: List<PreGenre>