image: introduce cover provider

This will be used to expose image data to android auto.

app/src/main/AndroidManifest.xml

@@ -100,6 +100,15 @@
             </intent-filter>
         </service>
 
+        <!--
+        Expose Auxio's cover data to the android system
+        -->
+        <provider
+            android:name=".image.CoverProvider"
+            android:authorities="org.oxycblt.auxio.image"
+            android:exported="true"
+            tools:ignore="ExportedContentProvider" />
+
         <!--
         Work around apps that blindly query for ACTION_MEDIA_BUTTON working.
         See the class for more info.

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

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2025 Auxio Project
+ * CoverProvider.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
+
+import android.content.ContentProvider
+import android.content.ContentValues
+import android.content.UriMatcher
+import android.database.Cursor
+import android.net.Uri
+import android.os.ParcelFileDescriptor
+import kotlinx.coroutines.runBlocking
+import org.oxycblt.auxio.image.covers.MutableSiloedCovers
+import org.oxycblt.auxio.image.covers.SiloedCoverId
+import org.oxycblt.musikr.cover.CoverIdentifier
+import org.oxycblt.musikr.cover.ObtainResult
+
+// AndroidManifest.xml addition
+
+// ImageProvider.java
+class CoverProvider : ContentProvider() {
+    override fun onCreate(): Boolean = true
+
+    override fun openFile(uri: Uri, mode: String): ParcelFileDescriptor? {
+        check(mode == "r") { "Unsupported mode: $mode" }
+        check(uriMatcher.match(uri) == 1) { "Unknown URI: $uri" }
+        val id = requireNotNull(uri.lastPathSegment) { "No ID in URI: $uri" }
+        val coverId = requireNotNull(SiloedCoverId.parse(id)) { "Invalid ID: $id" }
+        return runBlocking {
+            val siloedCovers =
+                MutableSiloedCovers.from(requireContext(), coverId.silo, CoverIdentifier.md5())
+            when (val res = siloedCovers.obtain(coverId.id)) {
+                is ObtainResult.Hit -> res.cover.fd()
+                is ObtainResult.Miss -> null
+            }
+        }
+    }
+
+    override fun getType(uri: Uri): String {
+        check(uriMatcher.match(uri) == 1) { "Unknown URI: $uri" }
+        return "image/*"
+    }
+
+    override fun query(
+        uri: Uri,
+        projection: Array<out String>?,
+        selection: String?,
+        selectionArgs: Array<out String>?,
+        sortOrder: String?
+    ): Cursor = throw UnsupportedOperationException()
+
+    override fun insert(uri: Uri, values: ContentValues?): Uri =
+        throw UnsupportedOperationException()
+
+    override fun delete(uri: Uri, selection: String?, selectionArgs: Array<out String>?): Int =
+        throw UnsupportedOperationException()
+
+    override fun update(
+        uri: Uri,
+        values: ContentValues?,
+        selection: String?,
+        selectionArgs: Array<out String>?
+    ): Int = throw UnsupportedOperationException()
+
+    companion object {
+        private const val AUTHORITY = "org.oxycblt.auxio.image"
+        private const val IMAGES_PATH = "covers"
+        private val uriMatcher =
+            UriMatcher(UriMatcher.NO_MATCH).apply { addURI(AUTHORITY, "$IMAGES_PATH/*", 1) }
+
+        val CONTENT_URI: Uri = Uri.parse("content://$AUTHORITY/$IMAGES_PATH")
+    }
+}

app/src/main/java/org/oxycblt/auxio/image/covers/MutableSiloedCovers.kt

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2024 Auxio Project
- * SiloedCovers.kt is part of Auxio.
+ * MutableSiloedCovers.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 +31,7 @@ import org.oxycblt.musikr.cover.MutableCovers
 import org.oxycblt.musikr.cover.ObtainResult
 import org.oxycblt.musikr.fs.app.AppFiles
 
-class SiloedCovers
+class MutableSiloedCovers
 private constructor(
     private val rootDir: File,
     private val silo: CoverSilo,
@@ -63,7 +63,7 @@ private constructor(
             context: Context,
             silo: CoverSilo,
             identifier: CoverIdentifier
-        ): SiloedCovers {
+        ): MutableSiloedCovers {
             val rootDir: File
             val revisionDir: File
             withContext(Dispatchers.IO) {
@@ -72,7 +72,7 @@ private constructor(
             }
             val files = AppFiles.at(revisionDir)
             val format = CoverFormat.jpeg(silo.params)
-            return SiloedCovers(rootDir, silo, FileCovers(files, format, identifier))
+            return MutableSiloedCovers(rootDir, silo, FileCovers(files, format, identifier))
         }
     }
 }

app/src/main/java/org/oxycblt/auxio/image/covers/SettingCovers.kt

@@ -44,5 +44,5 @@ constructor(private val imageSettings: ImageSettings, private val identifier: Co
         }
 
     private suspend fun siloedCovers(context: Context, revision: UUID, with: CoverParams) =
-        SiloedCovers.from(context, CoverSilo(revision, with), identifier)
+        MutableSiloedCovers.from(context, CoverSilo(revision, with), identifier)
 }