fix(subtitle): fix an issue where the first bitmap sub could not be displayed correctly

There was a problem that the first bitmap subtitle could not be displayed in the correct position
and size because it could not get the width and height of the video, due to the fact
that analyseduration and probesize are no longer increased.
This problem has been solved by caching the video size and using it.

SuRGeoNix/Flyleaf#502

Author: umlx5h

FlyleafLib/MediaPlayer/Subtitles.cs

@@ -103,8 +103,8 @@ public void Calculate()
         if (_player.Subtitles == null ||
             _player.Subtitles[_subIndex].Data.Bitmap == null ||
             _player.SubtitlesDecoders[_subIndex].SubtitlesStream == null ||
-            _player.SubtitlesDecoders[_subIndex].Width == 0 ||
-            _player.SubtitlesDecoders[_subIndex].Height == 0)
+            (_player.SubtitlesDecoders[_subIndex].Width == 0 && _player.SubtitlesManager[_subIndex].Width == 0) ||
+            (_player.SubtitlesDecoders[_subIndex].Height == 0 && _player.SubtitlesManager[_subIndex].Height == 0))
         {
             return;
         }
@@ -113,13 +113,20 @@ public void Calculate()
 
         // Calculate the ratio of the current width of the window to the width of the video
         double renderWidth = _player.VideoDecoder.Renderer.GetViewport.Width;
-        // double windowWidth = ActualWidth;
         double videoWidth = _player.SubtitlesDecoders[_subIndex].Width;
+        if (videoWidth == 0)
+        {
+            // Restore from cache because Width/Height may not be taken if the subtitle is not decoded enough.
+            videoWidth = _player.SubtitlesManager[_subIndex].Width;
+        }
 
         // double videoHeight_ = (int)(videoWidth / Player.VideoDemuxer.VideoStream.AspectRatio.Value);
         double renderHeight = _player.VideoDecoder.Renderer.GetViewport.Height;
-        // double windowHeight = ActualHeight;
         double videoHeight = _player.SubtitlesDecoders[_subIndex].Height;
+        if (videoHeight == 0)
+        {
+            videoHeight = _player.SubtitlesManager[_subIndex].Height;
+        }
 
         // In aspect ratio like a movie, a black background may be added to the top and bottom.
         // In this case, the subtitles should be placed based on the video display area, so the offset from the image rendering area excluding the black background should be taken into consideration.

FlyleafLib/MediaPlayer/SubtitlesManager.cs

@@ -123,6 +123,10 @@ public Language? LanguageSource
         }
     }
 
+    // For displaying bitmap subtitles, manage video width and height
+    public int Width { get; internal set; }
+    public int Height { get; internal set; }
+
     private readonly object _subsLocker = new();
     private readonly Config _config;
     private readonly int _subIndex;
@@ -426,7 +430,7 @@ public void Open(string url, int streamIndex, MediaType type, bool useBitmap, La
             try
             {
                 _cts = new CancellationTokenSource();
-                using SubtitleReader reader = new(_config, _subIndex);
+                using SubtitleReader reader = new(this, _config, _subIndex);
                 reader.Open(url, streamIndex, type, _cts.Token);
 
                 _cts.Token.ThrowIfCancellationRequested();
@@ -511,6 +515,8 @@ public void Clear()
             State = PositionState.First;
             LanguageSource = null;
             IsLoading = false;
+            Width = 0;
+            Height = 0;
         }
     }
 
@@ -541,6 +547,7 @@ protected bool Set<T>(ref T field, T value, [CallerMemberName] string? propertyN
 
 public unsafe class SubtitleReader : IDisposable
 {
+    private readonly SubManager _manager;
     private readonly Config _config;
     private readonly LogHandler Log;
     private readonly int _subIndex;
@@ -551,8 +558,9 @@ public unsafe class SubtitleReader : IDisposable
 
     private AVPacket* _packet = null;
 
-    public SubtitleReader(Config config, int subIndex)
+    public SubtitleReader(SubManager manager, Config config, int subIndex)
     {
+        _manager = manager;
         _config = config;
         Log = new LogHandler(("[#1]").PadRight(8, ' ') + $" [SubReader{subIndex + 1}    ] ");
 
@@ -705,6 +713,17 @@ public void ReadAll(bool useBitmap, Action<SubtitleData> addSub, CancellationTok
                 continue;
             }
 
+            if (_stream.IsBitmap)
+            {
+                // Cache the width and height of the video for use in displaying bitmap subtitles
+                // width and height may be 0 unless after decoding the subtitles
+                // In this case, bitmap subtitles cannot be displayed correctly, so the size should be cached here
+                if (_manager.Width != _decoder.CodecCtx->width)
+                    _manager.Width = _decoder.CodecCtx->width;
+                if (_manager.Height != _decoder.CodecCtx->height)
+                    _manager.Height = _decoder.CodecCtx->height;
+            }
+
             // Bitmap PGS has a special format.
             if (_stream.IsBitmap && prevSub != null
                 /*&& _stream->codecpar->codec_id == AVCodecID.AV_CODEC_ID_HDMV_PGS_SUBTITLE*/)