fixed naming

Renamed font file to be subfonts

Signed-off-by: Lance Chant <13349722+lancechant@users.noreply.github.com>

modules/mpv-player/android/src/main/java/expo/modules/mpvplayer/MPVLayerRenderer.kt

@@ -1,10 +1,13 @@
 package expo.modules.mpvplayer
 
 import android.content.Context
+import android.content.res.AssetManager
 import android.os.Handler
 import android.os.Looper
 import android.util.Log
 import android.view.Surface
+import java.io.File
+import java.io.FileOutputStream
 
 /**
  * MPV renderer that wraps libmpv for video playback.
@@ -101,6 +104,52 @@ class MPVLayerRenderer(private val context: Context) : MPVLib.EventObserver {
             MPVLib.create(context)
             MPVLib.addObserver(this)
             
+            /**
+             * Create mpv config directory and copy font files to ensure SubRip subtitles load properly on Android.
+             *
+             * Technical Background:
+             * ====================
+             * On Android, mpv requires access to a font file to render text-based subtitles, particularly SubRip (.srt)
+             * format subtitles. Without an available font in the config directory, mpv will fail to display subtitles
+             * even when subtitle tracks are properly detected and loaded.
+             *
+             * Why This Is Necessary:
+             * =====================
+             * 1. Android's font system is isolated from native libraries like mpv. While Android has system fonts,
+             *    mpv cannot access them directly due to sandboxing and library isolation.
+             *
+             * 2. SubRip subtitles require a font to render text overlay on video. When no font is available in the
+             *    configured directory, mpv either:
+             *    - Fails silently (subtitles don't appear)
+             *    - Falls back to a default font that may not support the required character set
+             *    - Crashes or produces rendering errors
+             *
+             * 3. By placing a font file (font.ttf) in mpv's config directory and setting that directory via
+             *    MPVLib.setOptionString("config-dir", ...), we ensure mpv has a known, accessible font source.
+             *
+             * Reference:
+             * =========
+             * This workaround is documented in the mpv-android project:
+             * https://github.com/mpv-android/mpv-android/issues/96
+             *
+             * The issue discusses that without a font in the config directory, SubRip subtitles fail to load
+             * properly on Android, and the solution is to copy a font file to a known location that mpv can access.
+             */
+            // Create mpv config directory and copy font files
+            val mpvDir = File(context.getExternalFilesDir(null) ?: context.filesDir, "mpv")
+            //Log.i(TAG, "mpv config dir: $mpvDir")
+            if (!mpvDir.exists()) mpvDir.mkdirs()
+            // This needs to be named `subfont.ttf` else it won't work
+            arrayOf("subfont.ttf").forEach { fileName ->
+                val file = File(mpvDir, fileName)
+                if (file.exists()) return@forEach
+                context.assets
+                    .open(fileName, AssetManager.ACCESS_STREAMING)
+                    .copyTo(FileOutputStream(file))
+            }
+            MPVLib.setOptionString("config", "yes")
+            MPVLib.setOptionString("config-dir", mpvDir.path)
+            
             // Configure mpv options before initialization (based on Findroid)
             MPVLib.setOptionString("vo", "gpu")
             MPVLib.setOptionString("gpu-context", "android")
@@ -124,7 +173,7 @@ class MPVLayerRenderer(private val context: Context) : MPVLib.EventObserver {
             MPVLib.setOptionString("hr-seek-framedrop", "yes")
             
             // Subtitle settings
-            MPVLib.setOptionString("sub-scale-with-window", "yes")
+            MPVLib.setOptionString("sub-scale-with-window", "no")
             MPVLib.setOptionString("sub-use-margins", "no")
             MPVLib.setOptionString("subs-match-os-language", "yes")
             MPVLib.setOptionString("subs-fallback", "yes")