Add Bgra4444

src/ImageSharp/Colors/PackedPixel/Alpha8.cs

@@ -9,7 +9,7 @@ namespace ImageSharp
     using System.Numerics;
 
     /// <summary>
-    /// Packed vector type containing a single 8 bit normalized W values that is ranging from 0 to 1.
+    /// Packed pixel type containing a single 8 bit normalized W values that is ranging from 0 to 1.
     /// </summary>
     public struct Alpha8 : IPackedPixel<byte>, IEquatable<Alpha8>
     {

src/ImageSharp/Colors/PackedPixel/Bgr565.cs

@@ -9,8 +9,7 @@ namespace ImageSharp
     using System.Numerics;
 
     /// <summary>
-    /// Packed vector type containing unsigned normalized values ranging from 0 to 1. 
-    /// The x and z components use 5 bits, and the y component uses 6 bits.
+    /// Packed pixel type containing unsigned normalized values ranging from 0 to 1. The x and z components use 5 bits, and the y component uses 6 bits.
     /// </summary>
     public struct Bgr565 : IPackedPixel<ushort>, IEquatable<Bgr565>
     {
@@ -155,7 +154,7 @@ namespace ImageSharp
         }
 
         /// <summary>
-        /// Packs a <see cref="float"/> components into a <see cref="ushort"/>.
+        /// Packs the <see cref="float"/> components into a <see cref="ushort"/>.
         /// </summary>
         /// <param name="x">The x-component</param>
         /// <param name="y">The y-component</param>

src/ImageSharp/Colors/PackedPixel/Bgra4444.cs

@@ -0,0 +1,164 @@
+// <copyright file="Bgra4444.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 pixel type containing unsigned normalized values, ranging from 0 to 1, using 4 bits each for x, y, z, and w.
+    /// </summary>
+    public struct Bgra4444 : IPackedPixel<ushort>, IEquatable<Bgra4444>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Bgra4444"/> 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 Bgra4444(float x, float y, float z, float w)
+        {
+            this.PackedValue = Pack(x, y, z, w);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Bgra4444"/> struct. 
+        /// </summary>
+        /// <param name="vector">The vector containing the components for the packed vector.</param>
+        public Bgra4444(Vector4 vector)
+        {
+            this.PackedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
+        }
+
+        /// <inheritdoc />
+        public ushort PackedValue { get; set; }
+
+        /// <summary>
+        /// Compares two <see cref="Bgra4444"/> objects for equality.
+        /// </summary>
+        /// <param name="left">The <see cref="Bgra4444"/> on the left side of the operand.</param>
+        /// <param name="right">The <see cref="Bgra4444"/> 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 ==(Bgra4444 left, Bgra4444 right)
+        {
+            return left.PackedValue == right.PackedValue;
+        }
+
+        /// <summary>
+        /// Compares two <see cref="Bgra4444"/> objects for equality.
+        /// </summary>
+        /// <param name="left">The <see cref="Bgra4444"/> on the left side of the operand.</param>
+        /// <param name="right">The <see cref="Bgra4444"/> 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 !=(Bgra4444 left, Bgra4444 right)
+        {
+            return left.PackedValue != right.PackedValue;
+        }
+
+        /// <inheritdoc />
+        public Vector4 ToVector4()
+        {
+            const float Max = 1 / 15F;
+
+            return new Vector4(
+                       ((this.PackedValue >> 8) & 0x0F) * Max,
+                       ((this.PackedValue >> 4) & 0x0F) * Max,
+                       (this.PackedValue & 0x0F) * Max,
+                       ((this.PackedValue >> 12) & 0x0F) * Max);
+        }
+
+        /// <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)vector.Z;
+                    bytes[startIndex + 1] = (byte)vector.Y;
+                    bytes[startIndex + 2] = (byte)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;
+                    break;
+                case ComponentOrder.XYZ:
+                    bytes[startIndex] = (byte)vector.X;
+                    bytes[startIndex + 1] = (byte)vector.Y;
+                    bytes[startIndex + 2] = (byte)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;
+                    break;
+                default:
+                    throw new NotSupportedException();
+            }
+        }
+
+        /// <inheritdoc />
+        public override bool Equals(object obj)
+        {
+            return (obj is Bgra4444) && this.Equals((Bgra4444)obj);
+        }
+
+        /// <inheritdoc />
+        public bool Equals(Bgra4444 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="ushort"/>.
+        /// </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="ushort"/> containing the packed values.</returns>
+        private static ushort Pack(float x, float y, float z, float w)
+        {
+            return (ushort)((((int)Math.Round(w.Clamp(0, 1) * 15F) & 0x0F) << 12) |
+                (((int)Math.Round(x.Clamp(0, 1) * 15F) & 0x0F) << 8) |
+                (((int)Math.Round(y.Clamp(0, 1) * 15F) & 0x0F) << 4) |
+                ((int)Math.Round(z.Clamp(0, 1) * 15F) & 0x0F));
+        }
+    }
+}

tests/ImageSharp.Tests/Colors/PackedVectorTests.cs

@@ -84,6 +84,8 @@ namespace ImageSharp.Tests.Colors
             float z = 0.5F;
             Assert.Equal(6160, new Bgr565(x, y, z).PackedValue);
 
+
+            // Test ordering
             byte[] rgb = new byte[3];
             byte[] rgba = new byte[4];
             byte[] bgr = new byte[3];
@@ -102,6 +104,56 @@ namespace ImageSharp.Tests.Colors
             Assert.Equal(bgra, new byte[] { 131, 0, 24, 255 });
         }
 
+        [Fact]
+        public void Bgra4444()
+        {
+            // Test the limits.
+            Assert.Equal(0x0, new Bgra4444(Vector4.Zero).PackedValue);
+            Assert.Equal(0xFFFF, new Bgra4444(Vector4.One).PackedValue);
+
+            // Test ToVector4.
+            Assert.True(Equal(Vector4.One, new Bgra4444(Vector4.One).ToVector4()));
+            Assert.True(Equal(Vector4.Zero, new Bgra4444(Vector4.Zero).ToVector4()));
+            Assert.True(Equal(Vector4.UnitX, new Bgra4444(Vector4.UnitX).ToVector4()));
+            Assert.True(Equal(Vector4.UnitY, new Bgra4444(Vector4.UnitY).ToVector4()));
+            Assert.True(Equal(Vector4.UnitZ, new Bgra4444(Vector4.UnitZ).ToVector4()));
+            Assert.True(Equal(Vector4.UnitW, new Bgra4444(Vector4.UnitW).ToVector4()));
+
+            // Test clamping.
+            Assert.True(Equal(Vector4.Zero, new Bgra4444(Vector4.One * -1234.0f).ToVector4()));
+            Assert.True(Equal(Vector4.One, new Bgra4444(Vector4.One * 1234.0f).ToVector4()));
+
+            // Make sure the swizzle is correct.
+            Assert.Equal(0x0F00, new Bgra4444(Vector4.UnitX).PackedValue);
+            Assert.Equal(0x00F0, new Bgra4444(Vector4.UnitY).PackedValue);
+            Assert.Equal(0x000F, new Bgra4444(Vector4.UnitZ).PackedValue);
+            Assert.Equal(0xF000, new Bgra4444(Vector4.UnitW).PackedValue);
+
+            float x = 0.1f;
+            float y = -0.3f;
+            float z = 0.5f;
+            float w = -0.7f;
+            Assert.Equal(520, new Bgra4444(x, y, z, w).PackedValue);
+
+            // Test ordering
+            byte[] rgb = new byte[3];
+            byte[] rgba = new byte[4];
+            byte[] bgr = new byte[3];
+            byte[] bgra = new byte[4];
+
+            new Bgra4444(x, y, z, w).ToBytes(rgb, 0, ComponentOrder.XYZ);
+            Assert.Equal(rgb, new byte[] { 34, 0, 136 });
+
+            new Bgra4444(x, y, z, w).ToBytes(rgba, 0, ComponentOrder.XYZW);
+            Assert.Equal(rgba, new byte[] { 34, 0, 136, 0 });
+
+            new Bgra4444(x, y, z, w).ToBytes(bgr, 0, ComponentOrder.ZYX);
+            Assert.Equal(bgr, new byte[] { 136, 0, 34 });
+
+            new Bgra4444(x, y, z, w).ToBytes(bgra, 0, ComponentOrder.ZYXW);
+            Assert.Equal(bgra, new byte[] { 136, 0, 34, 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

@@ -53,6 +53,7 @@ namespace ImageSharp.Tests
             {
                 Image image = file.CreateImage();
                 // Image<Bgr565, ushort> image = file.CreateImage().To<Bgr565, ushort>();
+                // Image<Bgra4444, ushort> image = file.CreateImage().To<Bgra4444, ushort>();
 
                 using (FileStream output = File.OpenWrite($"{path}/{file.FileName}"))
                 {