Add Rgba1010102, Make Bgr565 conversion more accurate.

src/ImageSharp/Colors/PackedPixel/Bgr565.cs

@@ -103,26 +103,26 @@ namespace ImageSharp
             switch (componentOrder)
             {
                 case ComponentOrder.ZYX:
-                    bytes[startIndex] = (byte)vector.Z;
-                    bytes[startIndex + 1] = (byte)vector.Y;
-                    bytes[startIndex + 2] = (byte)vector.X;
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.Z);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.X);
                     break;
                 case ComponentOrder.ZYXW:
-                    bytes[startIndex] = (byte)vector.Z;
-                    bytes[startIndex + 1] = (byte)vector.Y;
-                    bytes[startIndex + 2] = (byte)vector.X;
-                    bytes[startIndex + 3] = (byte)vector.W;
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.Z);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.X);
+                    bytes[startIndex + 3] = (byte)(float)Math.Round(vector.W);
                     break;
                 case ComponentOrder.XYZ:
-                    bytes[startIndex] = (byte)vector.X;
-                    bytes[startIndex + 1] = (byte)vector.Y;
-                    bytes[startIndex + 2] = (byte)vector.Z;
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.X);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.Z);
                     break;
                 case ComponentOrder.XYZW:
-                    bytes[startIndex] = (byte)vector.X;
-                    bytes[startIndex + 1] = (byte)vector.Y;
-                    bytes[startIndex + 2] = (byte)vector.Z;
-                    bytes[startIndex + 3] = (byte)vector.W;
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.X);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.Z);
+                    bytes[startIndex + 3] = (byte)(float)Math.Round(vector.W);
                     break;
                 default:
                     throw new NotSupportedException();

src/ImageSharp/Colors/PackedPixel/Rgba1010102.cs

@@ -0,0 +1,172 @@
+// <copyright file="Rgba1010102.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp
+{
+    using System;
+    using System.Numerics;
+
+    /// <summary>
+    /// Packed vector type containing unsigned normalized values ranging from 0 to 1.
+    /// The x, y and z components use 10 bits, and the w component uses 2 bits.
+    /// </summary>
+    public struct Rgba1010102 : IPackedPixel<uint>, IEquatable<Rgba1010102>, IPackedVector
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Rgba1010102"/> struct.
+        /// </summary>
+        /// <param name="x">The x-component</param>
+        /// <param name="y">The y-component</param>
+        /// <param name="z">The z-component</param>
+        /// <param name="w">The w-component</param>
+        public Rgba1010102(float x, float y, float z, float w)
+        {
+            this.PackedValue = Pack(x, y, z, w);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Rgba1010102"/> struct.
+        /// </summary>
+        /// <param name="vector">The vector containing the component values.</param>
+        public Rgba1010102(Vector4 vector)
+        {
+            this.PackedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
+        }
+
+        /// <inheritdoc />
+        public uint PackedValue { get; set; }
+
+        /// <summary>
+        /// Compares two <see cref="Rgba1010102"/> objects for equality.
+        /// </summary>
+        /// <param name="left">
+        /// The <see cref="Rgba1010102"/> on the left side of the operand.
+        /// </param>
+        /// <param name="right">
+        /// The <see cref="Rgba1010102"/> on the right side of the operand.
+        /// </param>
+        /// <returns>
+        /// True if the <paramref name="left"/> parameter is equal to the <paramref name="right"/> parameter; otherwise, false.
+        /// </returns>
+        public static bool operator ==(Rgba1010102 left, Rgba1010102 right)
+        {
+            return left.PackedValue == right.PackedValue;
+        }
+
+        /// <summary>
+        /// Compares two <see cref="Rgba1010102"/> objects for equality.
+        /// </summary>
+        /// <param name="left">
+        /// The <see cref="Rgba1010102"/> on the left side of the operand.
+        /// </param>
+        /// <param name="right">
+        /// The <see cref="Rgba1010102"/> on the right side of the operand.
+        /// </param>
+        /// <returns>
+        /// True if the <paramref name="left"/> parameter is not equal to the <paramref name="right"/> parameter; otherwise, false.
+        /// </returns>
+        public static bool operator !=(Rgba1010102 left, Rgba1010102 right)
+        {
+            return left.PackedValue != right.PackedValue;
+        }
+
+        /// <inheritdoc />
+        public Vector4 ToVector4()
+        {
+            return new Vector4(
+                ((this.PackedValue >> 0) & 0x03FF) / 1023F,
+                ((this.PackedValue >> 10) & 0x03FF) / 1023F,
+                ((this.PackedValue >> 20) & 0x03FF) / 1023F,
+                ((this.PackedValue >> 30) & 0x03) / 3F);
+        }
+
+        /// <inheritdoc />
+        public void PackFromVector4(Vector4 vector)
+        {
+            this.PackedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
+        }
+
+        /// <inheritdoc />
+        public void PackFromBytes(byte x, byte y, byte z, byte w)
+        {
+            this.PackFromVector4(new Vector4(x, y, z, w) / 255F);
+        }
+
+        /// <inheritdoc />
+        public void ToBytes(byte[] bytes, int startIndex, ComponentOrder componentOrder)
+        {
+            Vector4 vector = this.ToVector4() * 255F;
+
+            switch (componentOrder)
+            {
+                case ComponentOrder.ZYX:
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.Z);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.X);
+                    break;
+                case ComponentOrder.ZYXW:
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.Z);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.X);
+                    bytes[startIndex + 3] = (byte)(float)Math.Round(vector.W);
+                    break;
+                case ComponentOrder.XYZ:
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.X);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.Z);
+                    break;
+                case ComponentOrder.XYZW:
+                    bytes[startIndex] = (byte)(float)Math.Round(vector.X);
+                    bytes[startIndex + 1] = (byte)(float)Math.Round(vector.Y);
+                    bytes[startIndex + 2] = (byte)(float)Math.Round(vector.Z);
+                    bytes[startIndex + 3] = (byte)(float)Math.Round(vector.W);
+                    break;
+                default:
+                    throw new NotSupportedException();
+            }
+        }
+
+        /// <inheritdoc />
+        public override bool Equals(object obj)
+        {
+            return (obj is Rgba1010102) && this.Equals((Rgba1010102)obj);
+        }
+
+        /// <inheritdoc />
+        public bool Equals(Rgba1010102 other)
+        {
+            return this.PackedValue == other.PackedValue;
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return this.ToVector4().ToString();
+        }
+
+        /// <inheritdoc />
+        public override int GetHashCode()
+        {
+            return this.PackedValue.GetHashCode();
+        }
+
+        /// <summary>
+        /// Packs the <see cref="float"/> components into a <see cref="uint"/>.
+        /// </summary>
+        /// <param name="x">The x-component</param>
+        /// <param name="y">The y-component</param>
+        /// <param name="z">The z-component</param>
+        /// <param name="w">The w-component</param>
+        /// <returns>The <see cref="uint"/> containing the packed values.</returns>
+        private static uint Pack(float x, float y, float z, float w)
+        {
+            return (uint)(
+                (((int)Math.Round(x.Clamp(0, 1) * 1023F) & 0x03FF) << 0) |
+                (((int)Math.Round(y.Clamp(0, 1) * 1023F) & 0x03FF) << 10) |
+                (((int)Math.Round(z.Clamp(0, 1) * 1023F) & 0x03FF) << 20) |
+                (((int)Math.Round(w.Clamp(0, 1) * 3F) & 0x03) << 30));
+        }
+    }
+}

tests/ImageSharp.Tests/Colors/PackedPixelTests.cs

@@ -92,16 +92,16 @@ namespace ImageSharp.Tests.Colors
             byte[] bgra = new byte[4];
 
             new Bgr565(x, y, z).ToBytes(rgb, 0, ComponentOrder.XYZ);
-            Assert.Equal(rgb, new byte[] { 24, 0, 131 });
+            Assert.Equal(rgb, new byte[] { 25, 0, 132 });
 
             new Bgr565(x, y, z).ToBytes(rgba, 0, ComponentOrder.XYZW);
-            Assert.Equal(rgba, new byte[] { 24, 0, 131, 255 });
+            Assert.Equal(rgba, new byte[] { 25, 0, 132, 255 });
 
             new Bgr565(x, y, z).ToBytes(bgr, 0, ComponentOrder.ZYX);
-            Assert.Equal(bgr, new byte[] { 131, 0, 24 });
+            Assert.Equal(bgr, new byte[] { 132, 0, 25 });
 
             new Bgr565(x, y, z).ToBytes(bgra, 0, ComponentOrder.ZYXW);
-            Assert.Equal(bgra, new byte[] { 131, 0, 24, 255 });
+            Assert.Equal(bgra, new byte[] { 132, 0, 25, 255 });
         }
 
         [Fact]
@@ -606,6 +606,57 @@ namespace ImageSharp.Tests.Colors
             Assert.Equal(bgra, new byte[] { 0, 0, 25, 255 });
         }
 
+        [Fact]
+        public void Rgba1010102()
+        {
+            // Test the limits.
+            Assert.Equal((uint)0x0, new Rgba1010102(Vector4.Zero).PackedValue);
+            Assert.Equal(0xFFFFFFFF, new Rgba1010102(Vector4.One).PackedValue);
+
+            // Test ToVector4
+            Assert.True(Equal(Vector4.Zero, new Rgba1010102(Vector4.Zero).ToVector4()));
+            Assert.True(Equal(Vector4.One, new Rgba1010102(Vector4.One).ToVector4()));
+
+            // Test clamping.
+            Assert.True(Equal(Vector4.Zero, new Rgba1010102(Vector4.One * -1234.0f).ToVector4()));
+            Assert.True(Equal(Vector4.One, new Rgba1010102(Vector4.One * 1234.0f).ToVector4()));
+
+            // Test Ordering
+            float x = 0x2db;
+            float y = 0x36d;
+            float z = 0x3b7;
+            float w = 0x1;
+            Assert.Equal((uint)0x7B7DB6DB, new Rgba1010102(x / 0x3ff, y / 0x3ff, z / 0x3ff, w / 3).PackedValue);
+            x = 0.1f;
+            y = -0.3f;
+            z = 0.5f;
+            w = -0.7f;
+            Assert.Equal((uint)536871014, new Rgba1010102(x, y, z, w).PackedValue);
+
+            byte[] rgb = new byte[3];
+            byte[] rgba = new byte[4];
+            byte[] bgr = new byte[3];
+            byte[] bgra = new byte[4];
+
+            new Rgba1010102(x, y, z, w).ToBytes(rgb, 0, ComponentOrder.XYZ);
+            Assert.Equal(rgb, new byte[] { 25, 0, 128 });
+
+            new Rgba1010102(x, y, z, w).ToBytes(rgba, 0, ComponentOrder.XYZW);
+            Assert.Equal(rgba, new byte[] { 25, 0, 128, 0 });
+
+            new Rgba1010102(x, y, z, w).ToBytes(bgr, 0, ComponentOrder.ZYX);
+            Assert.Equal(bgr, new byte[] { 128, 0, 25 });
+
+            new Rgba1010102(x, y, z, w).ToBytes(bgra, 0, ComponentOrder.ZYXW);
+            Assert.Equal(bgra, new byte[] { 128, 0, 25, 0 });
+
+            // Alpha component accuracy will be awful.
+            Rgba1010102 r = new Rgba1010102();
+            r.PackFromBytes(25, 0, 128, 0);
+            r.ToBytes(rgba, 0, ComponentOrder.XYZW);
+            Assert.Equal(rgba, new byte[] { 25, 0, 128, 0 });
+        }
+
         // Comparison helpers with small tolerance to allow for floating point rounding during computations.
         public static bool Equal(float a, float b)
         {

tests/ImageSharp.Tests/Formats/GeneralFormatTests.cs

@@ -62,6 +62,7 @@ namespace ImageSharp.Tests
                 // Image<HalfVector2, uint> image = file.CreateImage().To<HalfVector2, uint>();
                 // Image<HalfVector4, ulong> image = file.CreateImage().To<HalfVector4, ulong>();
                 // Image<Rg32, uint> image = file.CreateImage().To<Rg32, uint>();
+                // Image<Rgba1010102, uint> image = file.CreateImage().To<Rgba1010102, uint>();
 
                 // TODO: Conversion between types who's vector ranges are different are not possible without scaling function, Make static version of known ones.
                 // Image<NormalizedByte2, ushort> image = file.CreateImage().To<NormalizedByte2, ushort>(v => (2F * v) - Vector4.One);