Support loading animations with BOM (#2167)

* Support loading animations with BOM

Fixes #2166

* New .NET version that just came out

binding/Binding/SKData.cs

@@ -103,7 +103,7 @@ public static SKData Create (Stream stream)
 			if (stream == null)
 				throw new ArgumentNullException (nameof (stream));
 			if (stream.CanSeek) {
-				return Create (stream, stream.Length);
+				return Create (stream, stream.Length - stream.Position);
 			} else {
 				using var memory = new SKDynamicMemoryWStream ();
 				using (var managed = new SKManagedStream (stream)) {

binding/Binding/Util.cs

@@ -12,6 +12,25 @@ internal unsafe static class Utils
 	{
 		internal const float NearlyZero = 1.0f / (1 << 12);
 
+		internal static int GetPreambleSize (SKData data)
+		{
+			_ = data ?? throw new ArgumentNullException (nameof (data));
+
+			var buffer = data.AsSpan ();
+			var len = buffer.Length;
+
+			if (len >= 2 && buffer[0] == 0xfe && buffer[1] == 0xff)
+				return 2;
+			else if (len >= 3 && buffer[0] == 0xef && buffer[1] == 0xbb && buffer[2] == 0xbf)
+				return 3;
+			else if (len >= 3 && buffer[0] == 0x2b && buffer[1] == 0x2f && buffer[2] == 0x76)
+				return 3;
+			else if (len >= 4 && buffer[0] == 0 && buffer[1] == 0 && buffer[2] == 0xfe && buffer[3] == 0xff)
+				return 4;
+			else
+				return 0;
+		}
+
 		internal static Span<byte> AsSpan (this IntPtr ptr, int size) =>
 			new Span<byte> ((void*)ptr, size);
 
@@ -105,8 +124,7 @@ public unsafe static class StringUtilities
 		// GetUnicodeStringLength
 
 		private static int GetUnicodeStringLength (SKTextEncoding encoding) =>
-			encoding switch
-			{
+			encoding switch {
 				SKTextEncoding.Utf8 => 1,
 				SKTextEncoding.Utf16 => 1,
 				SKTextEncoding.Utf32 => 2,
@@ -116,8 +134,7 @@ private static int GetUnicodeStringLength (SKTextEncoding encoding) =>
 		// GetCharacterByteSize
 
 		internal static int GetCharacterByteSize (this SKTextEncoding encoding) =>
-			encoding switch
-			{
+			encoding switch {
 				SKTextEncoding.Utf8 => 1,
 				SKTextEncoding.Utf16 => 2,
 				SKTextEncoding.Utf32 => 4,
@@ -156,8 +173,7 @@ internal static byte[] GetEncodedText (string text, SKTextEncoding encoding, boo
 		}
 
 		public static byte[] GetEncodedText (ReadOnlySpan<char> text, SKTextEncoding encoding) =>
-			encoding switch
-			{
+			encoding switch {
 				SKTextEncoding.Utf8 => Encoding.UTF8.GetBytes (text),
 				SKTextEncoding.Utf16 => Encoding.Unicode.GetBytes (text),
 				SKTextEncoding.Utf32 => Encoding.UTF32.GetBytes (text),
@@ -177,8 +193,7 @@ public static string GetString (byte[] data, int index, int count, SKTextEncodin
 			if (data == null)
 				throw new ArgumentNullException (nameof (data));
 
-			return encoding switch
-			{
+			return encoding switch {
 				SKTextEncoding.Utf8 => Encoding.UTF8.GetString (data, index, count),
 				SKTextEncoding.Utf16 => Encoding.Unicode.GetString (data, index, count),
 				SKTextEncoding.Utf32 => Encoding.UTF32.GetString (data, index, count),
@@ -197,8 +212,7 @@ public static string GetString (ReadOnlySpan<byte> data, int index, int count, S
 				return string.Empty;
 
 			fixed (byte* bp = data) {
-				return encoding switch
-				{
+				return encoding switch {
 					SKTextEncoding.Utf8 => Encoding.UTF8.GetString (bp, data.Length),
 					SKTextEncoding.Utf16 => Encoding.Unicode.GetString (bp, data.Length),
 					SKTextEncoding.Utf32 => Encoding.UTF32.GetString (bp, data.Length),

binding/SkiaSharp.Skottie/Animation.cs

@@ -21,6 +21,8 @@ void ISKNonVirtualReferenceCounted.UnreferenceNative ()
 		protected override void DisposeNative ()
 			=> SkottieApi.skottie_animation_delete (Handle);
 
+		// Parse
+
 		public static Animation? Parse (string json) =>
 			TryParse (json, out var animation)
 				? animation
@@ -34,6 +36,8 @@ public static bool TryParse (string json, [System.Diagnostics.CodeAnalysis.NotNu
 			return animation != null;
 		}
 
+		// Create
+
 		public static Animation? Create (Stream stream) =>
 			TryCreate (stream, out var animation)
 				? animation
@@ -56,8 +60,8 @@ public static bool TryCreate (SKStream stream, [System.Diagnostics.CodeAnalysis.
 		{
 			_ = stream ?? throw new ArgumentNullException (nameof (stream));
 
-			animation = GetObject (SkottieApi.skottie_animation_make_from_stream (stream.Handle));
-			return animation != null;
+			using var data = SKData.Create (stream);
+			return TryCreate (data, out animation);
 		}
 
 		public static Animation? Create (SKData data) =>
@@ -69,8 +73,13 @@ public static bool TryCreate (SKData data, [System.Diagnostics.CodeAnalysis.NotN
 		{
 			_ = data ?? throw new ArgumentNullException (nameof (data));
 
-			animation = GetObject (SkottieApi.skottie_animation_make_from_data ((void*)data.Data, (IntPtr)data.Size));
-			return animation != null;
+			var preamble = Utils.GetPreambleSize (data);
+			var span = data.AsSpan ().Slice (preamble);
+
+			fixed (byte* ptr = span) {
+				animation = GetObject (SkottieApi.skottie_animation_make_from_data (ptr, (IntPtr)span.Length));
+				return animation != null;
+			}
 		}
 
 		public static Animation? Create (string path) =>
@@ -82,16 +91,20 @@ public static bool TryCreate (string path, [System.Diagnostics.CodeAnalysis.NotN
 		{
 			_ = path ?? throw new ArgumentNullException (nameof (path));
 
-			animation = GetObject (SkottieApi.skottie_animation_make_from_file (path));
-			return animation != null;
+			using var data = SKData.Create (path);
+			return TryCreate (data, out animation);
 		}
 
+		// Render
+
 		public unsafe void Render (SKCanvas canvas, SKRect dst)
 			=> SkottieApi.skottie_animation_render (Handle, canvas.Handle, &dst);
 
 		public void Render (SKCanvas canvas, SKRect dst, AnimationRenderFlags flags)
 			=> SkottieApi.skottie_animation_render_with_flags (Handle, canvas.Handle, &dst, flags);
 
+		// Seek*
+
 		public void Seek (double percent, InvalidationController? ic = null)
 			=> SkottieApi.skottie_animation_seek (Handle, (float)percent, ic?.Handle ?? IntPtr.Zero);
 
@@ -104,6 +117,8 @@ public void SeekFrameTime (double seconds, InvalidationController? ic = null)
 		public void SeekFrameTime (TimeSpan time, InvalidationController? ic = null)
 			=> SeekFrameTime (time.TotalSeconds, ic);
 
+		// Properties
+
 		public TimeSpan Duration
 			=> TimeSpan.FromSeconds (SkottieApi.skottie_animation_get_duration (Handle));
 

scripts/azure-pipelines-variables.yml

@@ -15,7 +15,7 @@ variables:
   MONO_VERSION_LINUX: ''
   XCODE_VERSION: 13.2.1
   VISUAL_STUDIO_VERSION: '17/pre'
-  DOTNET_VERSION_PREVIEW: '6.0.301'
+  DOTNET_VERSION_PREVIEW: '6.0.302'
   DOTNET_WORKLOAD_SOURCE: 'https://aka.ms/dotnet/maui/6.0.300.json'
   CONFIGURATION: 'Release'
   DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true