feat(storage): Use Memory<byte> in buffer instead of byte[]

src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.skia.cs

@@ -16,9 +16,10 @@ private protected override bool TryOpenSourceSync(int? targetWidth, int? targetH
 		{
 			_surface ??= new SkiaCompositionSurface();
 
-			_surface.SetPixels(PixelWidth, PixelHeight, _buffer.Data);
+			_surface.SetPixels(PixelWidth, PixelHeight, _buffer.ToArray());
 
-			image = new ImageData {
+			image = new ImageData
+			{
 				Value = _surface
 			};
 

src/Uno.UWP/Devices/Midi/MidiChannelPressureMessage.cs

@@ -47,12 +47,12 @@ internal MidiChannelPressureMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the channel from 0-15 that this message applies to.
 		/// </summary>
-		public byte Channel => MidiHelpers.GetChannel(_buffer.Data[0]);
+		public byte Channel => MidiHelpers.GetChannel(_buffer.GetByte(0));
 
 		/// <summary>
 		/// Gets the pressure from 0-127.
 		/// </summary>
-		public byte Pressure => _buffer.Data[1];
+		public byte Pressure => _buffer.GetByte(0);
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiControlChangeMessage.cs

@@ -51,17 +51,17 @@ internal MidiControlChangeMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the channel from 0-15 that this message applies to.
 		/// </summary>
-		public byte Channel => MidiHelpers.GetChannel(_buffer.Data[0]);
+		public byte Channel => MidiHelpers.GetChannel(_buffer.GetByte(0));
 
 		/// <summary>
 		/// Gets the value from 0-127 to apply to the controller.
 		/// </summary>
-		public byte ControlValue => _buffer.Data[2];
+		public byte ControlValue => _buffer.GetByte(2);
 
 		/// <summary>
 		/// Gets controller from 0-127 to receive this message.
 		/// </summary>
-		public byte Controller => _buffer.Data[1];
+		public byte Controller => _buffer.GetByte(1);
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiNoteOffMessage.cs

@@ -50,17 +50,17 @@ internal MidiNoteOffMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the channel from 0-15 that this message applies to.
 		/// </summary>
-		public byte Channel => MidiHelpers.GetChannel(_buffer.Data[0]);
+		public byte Channel => MidiHelpers.GetChannel(_buffer.GetByte(0));
 
 		/// <summary>
 		/// Gets the note to turn off which is specified as a value from 0-127.
 		/// </summary>
-		public byte Note => _buffer.Data[1];
+		public byte Note => _buffer.GetByte(1);
 
 		/// <summary>
 		/// Gets the value of the velocity from 0-127.
 		/// </summary>
-		public byte Velocity => _buffer.Data[2];
+		public byte Velocity => _buffer.GetByte(2);
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiNoteOnMessage.cs

@@ -50,17 +50,17 @@ internal MidiNoteOnMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the channel from 0-15 that this message applies to.
 		/// </summary>
-		public byte Channel => MidiHelpers.GetChannel(_buffer.Data[0]);
+		public byte Channel => MidiHelpers.GetChannel(_buffer.GetByte(0));
 
 		/// <summary>
 		/// Gets the note to turn off which is specified as a value from 0-127.
 		/// </summary>
-		public byte Note => _buffer.Data[1];
+		public byte Note => _buffer.GetByte(1);
 
 		/// <summary>
 		/// Gets the value of the velocity from 0-127.
 		/// </summary>
-		public byte Velocity => _buffer.Data[2];
+		public byte Velocity => _buffer.GetByte(2);
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiPitchBendChangeMessage.cs

@@ -48,12 +48,12 @@ internal MidiPitchBendChangeMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the channel from 0-15 that this message applies to.
 		/// </summary>
-		public byte Channel => MidiHelpers.GetChannel(_buffer.Data[0]);
+		public byte Channel => MidiHelpers.GetChannel(_buffer.GetByte(0));
 
 		/// <summary>
 		/// Gets the pitch bend value which is specified as a 14-bit value from 0-16383.
 		/// </summary>
-		public ushort Bend => MidiHelpers.GetBend(_buffer.Data[1], _buffer.Data[2]);
+		public ushort Bend => MidiHelpers.GetBend(_buffer.GetByte(1), _buffer.GetByte(2));
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiPolyphonicKeyPressureMessage.cs

@@ -51,17 +51,17 @@ internal MidiPolyphonicKeyPressureMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the channel from 0-15 that this message applies to.
 		/// </summary>
-		public byte Channel => MidiHelpers.GetChannel(_buffer.Data[0]);
+		public byte Channel => MidiHelpers.GetChannel(_buffer.GetByte(0));
 
 		/// <summary>
 		/// Gets the note which is specified as a value from 0-127.
 		/// </summary>
-		public byte Note => _buffer.Data[1];
+		public byte Note => _buffer.GetByte(1);
 
 		/// <summary>
 		/// Gets the polyphonic key pressure which is specified as a value from 0-127.
 		/// </summary>
-		public byte Pressure => _buffer.Data[2];
+		public byte Pressure => _buffer.GetByte(2);
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiProgramChangeMessage.cs

@@ -47,12 +47,12 @@ internal MidiProgramChangeMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the channel from 0-15 that this message applies to.
 		/// </summary>
-		public byte Channel => MidiHelpers.GetChannel(_buffer.Data[0]);
+		public byte Channel => MidiHelpers.GetChannel(_buffer.GetByte(0));
 
 		/// <summary>
 		/// Gets the program to change from 0-127.
 		/// </summary>
-		public byte Program => _buffer.Data[1];
+		public byte Program => _buffer.GetByte(1);
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiSongPositionPointerMessage.cs

@@ -45,7 +45,7 @@ internal MidiSongPositionPointerMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the song position pointer encoded in a 14-bit value from 0-16383.
 		/// </summary>
-		public ushort Beats => MidiHelpers.GetBeats(_buffer.Data[1], _buffer.Data[2]);
+		public ushort Beats => MidiHelpers.GetBeats(_buffer.GetByte(1), _buffer.GetByte(2));
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Devices/Midi/MidiSongSelectMessage.cs

@@ -50,7 +50,7 @@ internal MidiSongSelectMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the song to select from 0-127.
 		/// </summary>
-		public byte Song => _buffer.Data[1];
+		public byte Song => _buffer.GetByte(1);
 
 		/// <summary>
 		/// Gets the duration from when the MidiInPort was created to the time the message was received.

src/Uno.UWP/Devices/Midi/MidiSystemExclusiveMessage.cs

@@ -25,7 +25,7 @@ public MidiSystemExclusiveMessage(IBuffer rawData)
 			}
 
 			if (rawData is Storage.Streams.Buffer inMemory &&
-				inMemory.Data[0] == (byte)MidiMessageType.EndSystemExclusive)
+				inMemory.GetByte(0) == (byte)MidiMessageType.EndSystemExclusive)
 			{
 				Type = MidiMessageType.EndSystemExclusive;
 			}

src/Uno.UWP/Devices/Midi/MidiTimeCodeMessage.cs

@@ -47,12 +47,12 @@ internal MidiTimeCodeMessage(byte[] rawData, TimeSpan timestamp)
 		/// <summary>
 		/// Gets the value of the frame type from 0-7.
 		/// </summary>
-		public byte FrameType => MidiHelpers.GetFrame(_buffer.Data[1]);
+		public byte FrameType => MidiHelpers.GetFrame(_buffer.GetByte(1));
 
 		/// <summary>
 		/// Gets the time code value from 0-15.
 		/// </summary>
-		public byte Values => MidiHelpers.GetFrameValues(_buffer.Data[1]);
+		public byte Values => MidiHelpers.GetFrameValues(_buffer.GetByte(1));
 
 		/// <summary>
 		/// Gets the array of bytes associated with the MIDI message, including status byte.

src/Uno.UWP/Storage/FileIO.cs

@@ -143,7 +143,7 @@ public static IAsyncAction AppendLinesAsync(IStorageFile file, IEnumerable<strin
 		/// <param name="buffer">The array of bytes to write.</param>
 		/// <returns>No object or value is returned when this method completes.</returns>
 		public static IAsyncAction WriteBytesAsync(IStorageFile file, byte[] buffer) =>
-			WriteBytesTaskAsync(file, buffer).AsAsyncAction();
+			WriteBytesTaskAsync(file, buffer, 0, buffer.Length).AsAsyncAction();
 
 		/// <summary>
 		/// Reads the contents of the specified file and returns a buffer.
@@ -249,7 +249,7 @@ private static async Task WriteTextTaskAsync(IStorageFile file, string contents,
 			await streamWriter.WriteAsync(contents);
 		}
 
-		private static async Task WriteBytesTaskAsync(IStorageFile file, byte[] buffer)
+		private static async Task WriteBytesTaskAsync(IStorageFile file, byte[] buffer, int index, int count)
 		{
 			if (file is null)
 			{
@@ -269,12 +269,8 @@ private static async Task<IBuffer> ReadBufferTaskAsync(IStorageFile file)
 
 		private static async Task WriteBufferTaskAsync(IStorageFile file, IBuffer buffer)
 		{
-			if (!(buffer is UwpBuffer inMemoryBuffer))
-			{
-				throw new NotSupportedException("The current implementation can only write a UwpBuffer");
-			}
-
-			await WriteBytesTaskAsync(file, inMemoryBuffer.Data);
+			var data = UwpBuffer.Cast(buffer).GetSegment();
+			await WriteBytesTaskAsync(file, data.Array!, data.Offset, data.Count);
 		}
 
 		private static async Task<Encoding> GetEncodingFromFileAsync(IStorageFile file)

src/Uno.UWP/Storage/Streams/Buffer.cs

@@ -1,27 +1,90 @@
 using System;
+using System.Runtime.InteropServices;
+using Windows.Foundation;
 
 namespace Windows.Storage.Streams
 {
 	public partial class Buffer : IBuffer
 	{
+		private readonly Memory<byte> _data;
+
+		internal static Buffer Cast(IBuffer impl)
+		{
+			if (impl is Buffer buffer)
+			{
+				return buffer;
+			}
+			else
+			{
+				throw new NotSupportedException("This type of buffer is not supported.");
+			}
+		}
+
 		public Buffer(uint capacity)
 		{
-			Data = new byte[capacity];
+			_data = new Memory<byte>(new byte[capacity]);
 		}
 
 		internal Buffer(byte[] data)
 		{
-			Data = data;
+			_data = new Memory<byte>(data);
+			Length = Capacity;
 		}
 
-		internal byte[] Data { get; }
+		internal Buffer(Memory<byte> data)
+		{
+			_data = data;
+			Length = (uint)data.Length;
+		}
 
-		public uint Capacity => (uint)Data.Length;
+		internal Span<byte> Span => _data.Span;
 
-		public uint Length
+		internal byte GetByte(int index)
 		{
-			get => (uint)Data.Length;
-			set => throw new NotSupportedException();
+			return _data.Span[index];
 		}
+
+		/// <summary>
+		/// Retrieve the underlying data array
+		/// </summary>
+		internal ArraySegment<byte> GetSegment()
+		{
+			if (MemoryMarshal.TryGetArray<byte>(_data, out var array))
+			{
+				return array;
+			}
+			else
+			{
+				throw new InvalidOperationException("Cannot get the segment from buffer.");
+			}
+		}
+
+		/// <summary>
+		/// **CLONES** the content of this buffer into a new byte[]
+		/// </summary>
+		internal byte[] ToArray()
+		{
+			return _data.ToArray();
+		}
+
+		/// <summary>
+		/// **CLONES** a part of the content of this buffer into a new byte[]
+		/// </summary>
+		internal byte[] ToArray(int start, int count)
+		{
+			return _data.Slice(start, count).ToArray();
+		}
+
+		internal void CopyTo(int index, byte[] destination, int destinationIndex, int count)
+		{
+			var src = _data.Slice(index, count);
+			var dst = new Memory<byte>(destination, destinationIndex, count);
+
+			src.CopyTo(dst);
+		}
+
+		public uint Capacity => (uint)_data.Length;
+
+		public uint Length { get; set; }
 	}
 }

src/Uno.UWP/Storage/Streams/DataReader.cs

@@ -11,13 +11,13 @@ namespace Windows.Storage.Streams
 	public sealed partial class DataReader : IDataReader, IDisposable
 	{
 		private readonly static ArrayPool<byte> _pool = ArrayPool<byte>.Create();
-		private readonly IBuffer _buffer;
+		private readonly Buffer _buffer;
 
 		private int _bufferPosition = 0;
 
 		private DataReader(IBuffer buffer)
 		{
-			_buffer = buffer ?? throw new ArgumentNullException(nameof(buffer));
+			_buffer = Buffer.Cast(buffer ?? throw new ArgumentNullException(nameof(buffer)));
 		}
 
 		/// <summary>
@@ -247,22 +247,19 @@ public string ReadString(uint codeUnitCount)
 			int length = (int)codeUnitCount;
 			VerifyRead(length);
 
-			if (!(_buffer is Buffer buffer))
-			{
-				throw new NotSupportedException("This type of buffer is not supported.");
-			}
+			var data = _buffer.GetSegment();
 
 			string result;
 			switch (UnicodeEncoding)
 			{
 				case UnicodeEncoding.Utf8:
-					result = Encoding.UTF8.GetString(buffer.Data, _bufferPosition, length);
+					result = Encoding.UTF8.GetString(data.Array!, data.Offset + _bufferPosition, length);
 					break;
 				case UnicodeEncoding.Utf16LE:
-					result = Encoding.Unicode.GetString(buffer.Data, _bufferPosition, length * 2);
+					result = Encoding.Unicode.GetString(data.Array!, data.Offset + _bufferPosition, length * 2);
 					break;
 				case UnicodeEncoding.Utf16BE:
-					result = Encoding.BigEndianUnicode.GetString(buffer.Data, _bufferPosition, length * 2);
+					result = Encoding.BigEndianUnicode.GetString(data.Array!, data.Offset + _bufferPosition, length * 2);
 					break;
 				default:
 					throw new InvalidOperationException("Unsupported UnicodeEncoding value.");
@@ -301,29 +298,12 @@ private void VerifyRead(int count)
 
 		private byte ReadByteFromBuffer()
 		{
-			byte nextByte;
-			switch (_buffer)
-			{
-				case Buffer buffer:
-					nextByte = buffer.Data[_bufferPosition];
-					break;
-				default:
-					throw new NotSupportedException("This buffer is not supported");
-			}
-			_bufferPosition++;
-			return nextByte;
+			return _buffer.GetByte(_bufferPosition++);
 		}
 
 		private void ReadBytesFromBuffer(byte[] data, int length)
 		{
-			switch (_buffer)
-			{
-				case Buffer buffer:
-					Array.Copy(buffer.Data, _bufferPosition, data, 0, length);
-					break;
-				default:
-					throw new NotSupportedException("This buffer is not supported");
-			}
+			_buffer.CopyTo(_bufferPosition, data, 0, length);
 			_bufferPosition += length;
 		}