uniform api and simplification for read only collections and dictiona…

…ries. Reduction of reference creation. Also fixes loading behavior expressed in #404

Unosquare.FFME.MediaElement/MediaElement.Properties.cs

@@ -2,7 +2,7 @@
 {
     using Common;
     using System;
-    using System.Collections.ObjectModel;
+    using System.Collections.Generic;
 
     public partial class MediaElement
     {
@@ -81,7 +81,7 @@ public TimeSpan? RemainingDuration
         /// Provides key-value pairs of the metadata contained in the media.
         /// Returns null when media has not been loaded.
         /// </summary>
-        public ReadOnlyDictionary<string, string> Metadata => MediaCore?.State.Metadata;
+        public IReadOnlyDictionary<string, string> Metadata => MediaCore?.State.Metadata;
 
         /// <summary>
         /// Provides stream, chapter and program info of the underlying media.

Unosquare.FFME.MediaElement/Platform/ClassProxy.cs

@@ -2,7 +2,6 @@
 {
     using System;
     using System.Collections.Generic;
-    using System.Collections.ObjectModel;
     using System.Linq;
     using System.Reflection;
 
@@ -37,14 +36,14 @@ public ClassProxy(Func<PropertyInfo, bool> matchClause)
                 proxies[property.Name] = proxy;
             }
 
-            Properties = new ReadOnlyDictionary<string, IPropertyProxy>(proxies);
-            PropertyNames = new ReadOnlyCollection<string>(Properties.Keys.ToArray());
-            ReadOnlyPropertyNames = new ReadOnlyCollection<string>(Properties
+            Properties = proxies;
+            PropertyNames = Properties.Keys.ToArray();
+            ReadOnlyPropertyNames = Properties
                 .Where(kvp => kvp.Value.CanRead && !kvp.Value.CanWrite)
-                .Select(kvp => kvp.Key).OrderBy(s => s).ToArray());
-            ReadWritePropertyNames = new ReadOnlyCollection<string>(Properties
+                .Select(kvp => kvp.Key).OrderBy(s => s).ToArray();
+            ReadWritePropertyNames = Properties
                 .Where(kvp => kvp.Value.CanRead && kvp.Value.CanWrite)
-                .Select(kvp => kvp.Key).OrderBy(s => s).ToArray());
+                .Select(kvp => kvp.Key).OrderBy(s => s).ToArray();
         }
 
         /// <summary>

Unosquare.FFME.MediaElement/Platform/PropertyMapper.cs

@@ -3,7 +3,6 @@
     using Common;
     using System;
     using System.Collections.Generic;
-    using System.Collections.ObjectModel;
     using System.Globalization;
     using System.Linq;
     using System.Runtime.CompilerServices;
@@ -24,16 +23,15 @@ internal static class PropertyMapper
         /// <exception cref="KeyNotFoundException">When a property exposed by the underlying MediaCore is not mapped.</exception>
         static PropertyMapper()
         {
-            MissingPropertyMappings = new ReadOnlyCollection<string>(
-                MediaEngineProxy.PropertyNames
+            MissingPropertyMappings = MediaEngineProxy.PropertyNames
                 .Where(p => !MediaElementProxy.PropertyNames.Contains(p))
-                .ToArray());
+                .ToArray();
         }
 
         /// <summary>
         /// Contains the property names found in the Media Engine State type, but not found in the Media Element.
         /// </summary>
-        public static IReadOnlyCollection<string> MissingPropertyMappings { get; }
+        public static IReadOnlyList<string> MissingPropertyMappings { get; }
 
         /// <summary>
         /// Sets the value for the specified property name on the given instance.

Unosquare.FFME.Windows/Common/RenderingSubtitlesEventArgs.cs

@@ -22,8 +22,8 @@ public sealed class RenderingSubtitlesEventArgs : RenderingEventArgs
         /// <param name="duration">The duration.</param>
         /// <param name="clock">The clock.</param>
         internal RenderingSubtitlesEventArgs(
-            List<string> text,
-            List<string> originalText,
+            IList<string> text,
+            IList<string> originalText,
             AVSubtitleType format,
             IMediaEngineState engineState,
             StreamInfo stream,
@@ -42,13 +42,13 @@ internal RenderingSubtitlesEventArgs(
         /// This is what the default subtitle renderer will display
         /// on the screen.
         /// </summary>
-        public List<string> Text { get; }
+        public IList<string> Text { get; }
 
         /// <summary>
         /// Gets the text as originally decoded including
         /// all markup and formatting.
         /// </summary>
-        public List<string> OriginalText { get; }
+        public IList<string> OriginalText { get; }
 
         /// <summary>
         /// Gets the type of subtitle format the original

Unosquare.FFME.Windows/Common/RenderingVideoEventArgs.cs

@@ -2,7 +2,7 @@
 {
     using ClosedCaptions;
     using System;
-    using System.Collections.ObjectModel;
+    using System.Collections.Generic;
 
     /// <summary>
     /// The video rendering event arguments.
@@ -24,7 +24,7 @@ public sealed class RenderingVideoEventArgs : RenderingEventArgs
         /// <param name="clock">The clock.</param>
         internal RenderingVideoEventArgs(
             BitmapDataBuffer bitmap,
-            ReadOnlyCollection<ClosedCaptionPacket> closedCaptions,
+            IReadOnlyList<ClosedCaptionPacket> closedCaptions,
             string smtpeTimeCode,
             long pictureNumber,
             IMediaEngineState engineState,
@@ -49,7 +49,7 @@ internal RenderingVideoEventArgs(
         /// <summary>
         /// Gets the closed caption decoded packets.
         /// </summary>
-        public ReadOnlyCollection<ClosedCaptionPacket> ClosedCaptions { get; }
+        public IReadOnlyList<ClosedCaptionPacket> ClosedCaptions { get; }
 
         /// <summary>
         /// Gets the display picture number (frame number).

Unosquare.FFME/Common/IMediaEngineState.cs

@@ -1,7 +1,7 @@
 namespace Unosquare.FFME.Common
 {
     using System;
-    using System.Collections.ObjectModel;
+    using System.Collections.Generic;
 
     /// <summary>
     /// Provides Media Engine state as read-only properties.
@@ -203,7 +203,7 @@ public interface IMediaEngineState
         /// <summary>
         /// Gets the media metadata such as title, language, etc.
         /// </summary>
-        ReadOnlyDictionary<string, string> Metadata { get; }
+        IReadOnlyDictionary<string, string> Metadata { get; }
 
         /// <summary>
         /// Gets the duration of the media.

Unosquare.FFME/Common/MediaInfo.cs

@@ -4,7 +4,6 @@
     using FFmpeg.AutoGen;
     using System;
     using System.Collections.Generic;
-    using System.Collections.ObjectModel;
     using System.Linq;
 
     /// <summary>
@@ -30,10 +29,10 @@ internal MediaInfo(MediaContainer container)
             Duration = ic->duration != ffmpeg.AV_NOPTS_VALUE ? ic->duration.ToTimeSpan() : TimeSpan.MinValue;
             BitRate = ic->bit_rate < 0 ? 0 : ic->bit_rate;
 
-            Streams = new ReadOnlyDictionary<int, StreamInfo>(ExtractStreams(ic).ToDictionary(k => k.StreamIndex, v => v));
-            Chapters = new ReadOnlyCollection<ChapterInfo>(ExtractChapters(ic));
-            Programs = new ReadOnlyCollection<ProgramInfo>(ExtractPrograms(ic, Streams));
-            BestStreams = new ReadOnlyDictionary<AVMediaType, StreamInfo>(FindBestStreams(ic, Streams));
+            Streams = ExtractStreams(ic).ToDictionary(k => k.StreamIndex, v => v);
+            Chapters = ExtractChapters(ic);
+            Programs = ExtractPrograms(ic, Streams);
+            BestStreams = FindBestStreams(ic, Streams);
         }
 
         #endregion
@@ -54,7 +53,7 @@ internal MediaInfo(MediaContainer container)
         /// Gets the metadata for the input. This may include stuff like title, creation date, company name, etc.
         /// Individual stream components, chapters and programs may contain additional metadata.
         /// </summary>
-        public ReadOnlyDictionary<string, string> Metadata { get; }
+        public IReadOnlyDictionary<string, string> Metadata { get; }
 
         /// <summary>
         /// Gets the duration of the input as reported by the container format.
@@ -78,23 +77,23 @@ internal MediaInfo(MediaContainer container)
         /// <summary>
         /// Gets a list of chapters.
         /// </summary>
-        public ReadOnlyCollection<ChapterInfo> Chapters { get; }
+        public IReadOnlyList<ChapterInfo> Chapters { get; }
 
         /// <summary>
         /// Gets a list of programs with their associated streams.
         /// </summary>
-        public ReadOnlyCollection<ProgramInfo> Programs { get; }
+        public IReadOnlyList<ProgramInfo> Programs { get; }
 
         /// <summary>
         /// Gets the dictionary of stream information components by stream index.
         /// </summary>
-        public ReadOnlyDictionary<int, StreamInfo> Streams { get; }
+        public IReadOnlyDictionary<int, StreamInfo> Streams { get; }
 
         /// <summary>
         /// Provides access to the best streams of each media type found in the container.
         /// This uses some internal FFmpeg heuristics.
         /// </summary>
-        public ReadOnlyDictionary<AVMediaType, StreamInfo> BestStreams { get; }
+        public IReadOnlyDictionary<AVMediaType, StreamInfo> BestStreams { get; }
 
         #endregion
 
@@ -147,7 +146,7 @@ private static List<StreamInfo> ExtractStreams(AVFormatContext* inputContext)
                 {
                     StreamId = s->id,
                     StreamIndex = s->index,
-                    Metadata = new ReadOnlyDictionary<string, string>(FFDictionary.ToDictionary(s->metadata)),
+                    Metadata = FFDictionary.ToDictionary(s->metadata),
                     CodecType = codecContext->codec_type,
                     CodecTypeName = ffmpeg.av_get_media_type_string(codecContext->codec_type),
                     Codec = codecContext->codec_id,
@@ -184,11 +183,8 @@ private static List<StreamInfo> ExtractStreams(AVFormatContext* inputContext)
                 };
 
                 // Extract valid hardware configurations
-                stream.HardwareDevices = new ReadOnlyCollection<HardwareDeviceInfo>(
-                    HardwareAccelerator.GetCompatibleDevices(stream.Codec));
-
-                stream.HardwareDecoders = new ReadOnlyCollection<string>(
-                    GetHardwareDecoders(stream.Codec));
+                stream.HardwareDevices = HardwareAccelerator.GetCompatibleDevices(stream.Codec);
+                stream.HardwareDecoders = GetHardwareDecoders(stream.Codec);
 
                 // TODO: I chose not to include Side data but I could easily do so
                 // https://ffmpeg.org/doxygen/3.2/dump_8c_source.html
@@ -207,7 +203,7 @@ private static List<StreamInfo> ExtractStreams(AVFormatContext* inputContext)
         /// <param name="ic">The ic.</param>
         /// <param name="streams">The streams.</param>
         /// <returns>The star infos.</returns>
-        private static Dictionary<AVMediaType, StreamInfo> FindBestStreams(AVFormatContext* ic, ReadOnlyDictionary<int, StreamInfo> streams)
+        private static Dictionary<AVMediaType, StreamInfo> FindBestStreams(AVFormatContext* ic, IReadOnlyDictionary<int, StreamInfo> streams)
         {
             // Initialize and clear all the stream indexes.
             var streamIndexes = new Dictionary<AVMediaType, int>();
@@ -278,7 +274,7 @@ private static List<ChapterInfo> ExtractChapters(AVFormatContext* ic)
                     EndTime = c->end.ToTimeSpan(c->time_base),
                     Index = i,
                     ChapterId = c->id,
-                    Metadata = new ReadOnlyDictionary<string, string>(FFDictionary.ToDictionary(c->metadata))
+                    Metadata = FFDictionary.ToDictionary(c->metadata)
                 };
 
                 result.Add(chapter);
@@ -293,7 +289,7 @@ private static List<ChapterInfo> ExtractChapters(AVFormatContext* ic)
         /// <param name="ic">The ic.</param>
         /// <param name="streams">The streams.</param>
         /// <returns>The program information.</returns>
-        private static List<ProgramInfo> ExtractPrograms(AVFormatContext* ic, ReadOnlyDictionary<int, StreamInfo> streams)
+        private static List<ProgramInfo> ExtractPrograms(AVFormatContext* ic, IReadOnlyDictionary<int, StreamInfo> streams)
         {
             var result = new List<ProgramInfo>(128);
             if (ic->programs == null) return result;
@@ -304,7 +300,7 @@ private static List<ProgramInfo> ExtractPrograms(AVFormatContext* ic, ReadOnlyDi
 
                 var program = new ProgramInfo
                 {
-                    Metadata = new ReadOnlyDictionary<string, string>(FFDictionary.ToDictionary(p->metadata)),
+                    Metadata = FFDictionary.ToDictionary(p->metadata),
                     ProgramId = p->id,
                     ProgramNumber = p->program_num
                 };
@@ -317,7 +313,7 @@ private static List<ProgramInfo> ExtractPrograms(AVFormatContext* ic, ReadOnlyDi
                         associatedStreams.Add(streams[streamIndex]);
                 }
 
-                program.Streams = new ReadOnlyCollection<StreamInfo>(associatedStreams);
+                program.Streams = associatedStreams;
 
                 result.Add(program);
             }
@@ -535,17 +531,17 @@ public class StreamInfo
         /// <summary>
         /// Gets the stream's metadata.
         /// </summary>
-        public ReadOnlyDictionary<string, string> Metadata { get; internal set; }
+        public IReadOnlyDictionary<string, string> Metadata { get; internal set; }
 
         /// <summary>
         /// Gets the compatible hardware device configurations for the stream's codec.
         /// </summary>
-        public ReadOnlyCollection<HardwareDeviceInfo> HardwareDevices { get; internal set; }
+        public IReadOnlyList<HardwareDeviceInfo> HardwareDevices { get; internal set; }
 
         /// <summary>
         /// Gets a list of compatible hardware decoder names.
         /// </summary>
-        public ReadOnlyCollection<string> HardwareDecoders { get; internal set; }
+        public IReadOnlyList<string> HardwareDecoders { get; internal set; }
 
         /// <summary>
         /// Gets the language string from the stream's metadata.
@@ -582,7 +578,7 @@ public class ChapterInfo
         /// <summary>
         /// Gets the chapter metadata.
         /// </summary>
-        public ReadOnlyDictionary<string, string> Metadata { get; internal set; }
+        public IReadOnlyDictionary<string, string> Metadata { get; internal set; }
     }
 
     /// <summary>
@@ -603,12 +599,12 @@ public class ProgramInfo
         /// <summary>
         /// Gets the program metadata.
         /// </summary>
-        public ReadOnlyDictionary<string, string> Metadata { get; internal set; }
+        public IReadOnlyDictionary<string, string> Metadata { get; internal set; }
 
         /// <summary>
         /// Gets the associated program streams.
         /// </summary>
-        public ReadOnlyCollection<StreamInfo> Streams { get; internal set; }
+        public IReadOnlyList<StreamInfo> Streams { get; internal set; }
 
         /// <summary>
         /// Gets the name of the program. Empty if unavailable.

Unosquare.FFME/Container/MediaComponentSet.cs

@@ -5,7 +5,6 @@
     using Primitives;
     using System;
     using System.Collections.Generic;
-    using System.Collections.ObjectModel;
     using System.Runtime.CompilerServices;
 
     /// <summary>
@@ -23,8 +22,8 @@ internal sealed class MediaComponentSet : IDisposable
         private readonly object BufferSyncLock = new object();
         private readonly AtomicBoolean m_IsDisposed = new AtomicBoolean(false);
 
-        private ReadOnlyCollection<MediaComponent> m_All = new ReadOnlyCollection<MediaComponent>(new List<MediaComponent>(0));
-        private ReadOnlyCollection<MediaType> m_MediaTypes = new ReadOnlyCollection<MediaType>(new List<MediaType>(0));
+        private IReadOnlyList<MediaComponent> m_All = new List<MediaComponent>(0);
+        private IReadOnlyList<MediaType> m_MediaTypes = new List<MediaType>(0);
 
         private int m_Count;
         private TimeSpan? m_PlaybackStartTime;
@@ -81,15 +80,15 @@ public int Count
         /// <summary>
         /// Gets the available component media types.
         /// </summary>
-        public ReadOnlyCollection<MediaType> MediaTypes
+        public IReadOnlyList<MediaType> MediaTypes
         {
             get { lock (ComponentSyncLock) return m_MediaTypes; }
         }
 
         /// <summary>
         /// Gets all the components in a read-only collection.
         /// </summary>
-        public ReadOnlyCollection<MediaComponent> All
+        public IReadOnlyList<MediaComponent> All
         {
             get { lock (ComponentSyncLock) return m_All; }
         }
@@ -541,8 +540,8 @@ private unsafe void UpdateComponentBackingFields()
                 allMediaTypes.Add(MediaType.Subtitle);
             }
 
-            m_All = new ReadOnlyCollection<MediaComponent>(allComponents);
-            m_MediaTypes = new ReadOnlyCollection<MediaType>(allMediaTypes);
+            m_All = allComponents;
+            m_MediaTypes = allMediaTypes;
             m_Count = allComponents.Count;
 
             // Find Start time, duration and end time