CopyRGBBytesStretchedTo

src/ImageSharp/Formats/Jpg/Components/DCT.cs

@@ -3,13 +3,14 @@
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
 // ReSharper disable InconsistentNaming
+
 namespace ImageSharp.Formats
 {
     using System.Numerics;
     using System.Runtime.CompilerServices;
 
     /// <summary>
-    /// Contains forward & inverse DCT implementations
+    /// Contains forward and inverse DCT implementations
     /// </summary>
     internal static class DCT
     {
@@ -35,16 +36,27 @@ namespace ImageSharp.Formats
 
 #pragma warning disable SA1310 // FieldNamesMustNotContainUnderscore
         private static readonly Vector4 C_1_175876 = new Vector4(1.175876f);
+
         private static readonly Vector4 C_1_961571 = new Vector4(-1.961571f);
+
         private static readonly Vector4 C_0_390181 = new Vector4(-0.390181f);
+
         private static readonly Vector4 C_0_899976 = new Vector4(-0.899976f);
+
         private static readonly Vector4 C_2_562915 = new Vector4(-2.562915f);
+
         private static readonly Vector4 C_0_298631 = new Vector4(0.298631f);
+
         private static readonly Vector4 C_2_053120 = new Vector4(2.053120f);
+
         private static readonly Vector4 C_3_072711 = new Vector4(3.072711f);
+
         private static readonly Vector4 C_1_501321 = new Vector4(1.501321f);
+
         private static readonly Vector4 C_0_541196 = new Vector4(0.541196f);
+
         private static readonly Vector4 C_1_847759 = new Vector4(-1.847759f);
+
         private static readonly Vector4 C_0_765367 = new Vector4(0.765367f);
 
         private static readonly Vector4 C_0_125 = new Vector4(0.1250f);
@@ -52,7 +64,7 @@ namespace ImageSharp.Formats
         private static readonly Vector4 InvSqrt2 = new Vector4(0.707107f);
 
         /// <summary>
-        /// Do IDCT internal operations on the left part of the block. Original source:
+        /// Do IDCT internal operations on the left part of the block. Original src:
         /// https://github.com/norishigefukushima/dct_simd/blob/master/dct/dct8x8_simd.cpp#L261
         /// </summary>
         /// <param name="d">Destination block</param>
@@ -109,7 +121,7 @@ namespace ImageSharp.Formats
 
         /// <summary>
         /// Do IDCT internal operations on the right part of the block.
-        /// Original source:
+        /// Original src:
         /// https://github.com/norishigefukushima/dct_simd/blob/master/dct/dct8x8_simd.cpp#L261
         /// </summary>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -163,7 +175,6 @@ namespace ImageSharp.Formats
             d.V4R = my3 - mb3;
         }
 
-
         /// <summary>
         /// Original:
         /// <see>
@@ -220,7 +231,6 @@ namespace ImageSharp.Formats
             Vector4 w0 = new Vector4(0.541196f);
             Vector4 w1 = new Vector4(1.306563f);
 
-
             d.V2L = (w0 * c2) + (w1 * c3);
 
             d.V6L = (w0 * c3) - (w1 * c2);
@@ -325,7 +335,6 @@ namespace ImageSharp.Formats
             Vector4 w0 = new Vector4(0.541196f);
             Vector4 w1 = new Vector4(1.306563f);
 
-
             d.V2R = (w0 * c2) + (w1 * c3);
 
             d.V6R = (w0 * c3) - (w1 * c2);
@@ -373,23 +382,34 @@ namespace ImageSharp.Formats
             }*/
         }
 
-        public static void TransformFDCT(ref Block8x8F s, ref Block8x8F d, ref Block8x8F temp, bool offsetSourceByNeg128 = true)
+        /// <summary>
+        /// Apply floating point IDCT transformation into dest, using a temporary block 'temp' provided by the caller (optimization)
+        /// </summary>
+        /// <param name="src">Source</param>
+        /// <param name="dest">Destination</param>
+        /// <param name="temp">Temporary block provided by the caller</param>
+        /// <param name="offsetSourceByNeg128">If true, a constant -128.0 offset is applied for all values before FDCT </param>
+        public static void TransformFDCT(
+            ref Block8x8F src,
+            ref Block8x8F dest,
+            ref Block8x8F temp,
+            bool offsetSourceByNeg128 = true)
         {
-            s.TransposeInto(ref temp);
+            src.TransposeInto(ref temp);
             if (offsetSourceByNeg128)
             {
                 temp.AddToAllInplace(new Vector4(-128));
             }
 
-            FDCT8x4_LeftPart(ref temp, ref d);
-            FDCT8x4_RightPart(ref temp, ref d);
+            FDCT8x4_LeftPart(ref temp, ref dest);
+            FDCT8x4_RightPart(ref temp, ref dest);
+
+            dest.TransposeInto(ref temp);
+
+            FDCT8x4_LeftPart(ref temp, ref dest);
+            FDCT8x4_RightPart(ref temp, ref dest);
 
-            d.TransposeInto(ref temp);
-            
-            FDCT8x4_LeftPart(ref temp, ref d);
-            FDCT8x4_RightPart(ref temp, ref d);
-            
-            d.MultiplyAllInplace(C_0_125);
+            dest.MultiplyAllInplace(C_0_125);
         }
     }
 }

src/ImageSharp/Formats/Jpg/JpegEncoderCore.cs

@@ -34,7 +34,10 @@ namespace ImageSharp.Formats
                 {
                     0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0
                 },
-                new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 }),
+                new byte[]
+                {
+                    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
+                }),
             new HuffmanSpec(
                 new byte[]
                 {
@@ -562,8 +565,7 @@ namespace ImageSharp.Formats
                 ColorRGBToYCbCr(asStandardColorAccessor, x, y, yBlockRaw, cbBlockRaw, crBlockRaw);
                 return;
             }
-
-
+            
             Vector4 maxBytes = new Vector4(255f);
             Vector4 half = new Vector4(0.5f);
             int xmax = pixels.Width - 1;
@@ -590,9 +592,8 @@ namespace ImageSharp.Formats
                 }
             }
         }
-
-
         
+        // ReSharper disable once InconsistentNaming
         private static void ColorRGBToYCbCr(
             PixelAccessor<Color> pixels,
             int x,
@@ -632,10 +633,6 @@ namespace ImageSharp.Formats
                     crBlockRaw[index] = cr;
                 }
             }
-
-            //(((y * pixels.Width) + x) * colorSize);
-
-
         }
 
         
@@ -934,13 +931,11 @@ namespace ImageSharp.Formats
         {
             Block8x8F b = new Block8x8F();
             
-
             BlockQuad cb = new BlockQuad();
             BlockQuad cr = new BlockQuad();
             Block8x8F* cbPtr = (Block8x8F*)cb.Data;
             Block8x8F* crPtr = (Block8x8F*)cr.Data;
             
-
             Block8x8F temp1 = new Block8x8F();
             Block8x8F temp2 = new Block8x8F();
 

src/ImageSharp/Formats/Jpg/JpegUtils.cs

@@ -13,12 +13,12 @@
             *dest = *source; // B
         }
 
-        internal static unsafe void RepeatPixelsBottomRight<TColor>(PixelArea<TColor> area, int fromX, int fromY)
+        private static unsafe void StretchPixels<TColor>(PixelArea<TColor> area, int fromX, int fromY)
             where TColor : struct, IPackedPixel, IEquatable<TColor>
         {
-            if (fromX <= 0 || fromY <= 0 || fromX >= area.Width || fromY >= area.Height)
+            if (IsInvalidStretchArea(area, fromX, fromY))
             {
-                throw new InvalidOperationException();
+                return;
             }
 
             for (int y = 0; y < fromY; y++)
@@ -49,5 +49,24 @@
                 }
             }
         }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static bool IsInvalidStretchArea<TColor>(PixelArea<TColor> area, int fromX, int fromY) where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            return fromX <= 0 || fromY <= 0 || fromX >= area.Width || fromY >= area.Height;
+        }
+
+        public static void CopyRGBBytesStretchedTo<TColor>(
+            this PixelAccessor<TColor> pixels,
+            PixelArea<TColor> dest,
+            int sourceY,
+            int sourceX)
+            where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            pixels.CopyTo(dest, sourceY, sourceX);
+            int stretchFromX = pixels.Width - sourceX;
+            int stretchFromY = pixels.Height - sourceY;
+            StretchPixels(dest, stretchFromX, stretchFromY);
+        }
     }
 }

tests/ImageSharp.Tests/Formats/Jpg/JpegTests.cs

@@ -5,9 +5,12 @@ using System.Linq;
 using ImageSharp.Formats;
 using Xunit;
 using Xunit.Abstractions;
+// ReSharper disable InconsistentNaming
 
 namespace ImageSharp.Tests
 {
+    using System.Numerics;
+
     public class JpegTests
     {
         private ITestOutputHelper Output { get; }
@@ -53,5 +56,100 @@ namespace ImageSharp.Tests
                 image.Save(outputStream, encoder);
             }
         }
+
+        public static Image<TColor> CreateTestImage<TColor>(GenericFactory<TColor> factory)
+            where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            Image<TColor> image = factory.CreateImage(10, 10);
+
+            using (var pixels = image.Lock())
+            {
+                for (int i = 0; i < 10; i++)
+                {
+                    for (int j = 0; j < 10; j++)
+                    {
+                        Vector4 v = new Vector4(i/10f, j/10f, 0, 1);
+                        
+                        TColor color = default(TColor);
+                        color.PackFromVector4(v);
+
+                        pixels[i, j] = color;
+                    }
+                }
+            }
+            return image;
+        }
+
+        [Theory]
+        [WithMemberFactory(nameof(CreateTestImage), PixelTypes.Color | PixelTypes.StandardImageClass | PixelTypes.Argb)]
+        public void CopyStretchedRGBTo_FromOrigo<TColor>(TestImageProvider<TColor> provider)
+            where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            var src = provider.GetImage();
+
+            PixelArea<TColor> area = new PixelArea<TColor>(8, 8, ComponentOrder.XYZ);
+            var dest = provider.Factory.CreateImage(8, 8);
+
+            using (var s = src.Lock())
+            {
+                using (var d = dest.Lock())
+                {
+                    s.CopyRGBBytesStretchedTo(area, 0, 0);
+                    d.CopyFrom(area, 0, 0);
+
+                    Assert.Equal(s[0, 0], d[0, 0]);
+                    Assert.Equal(s[7, 0], d[7, 0]);
+                    Assert.Equal(s[0, 7], d[0, 7]);
+                    Assert.Equal(s[7, 7], d[7, 7]);
+                }
+            }
+        }
+
+        [Theory]
+        [WithMemberFactory(nameof(CreateTestImage), PixelTypes.Color | PixelTypes.StandardImageClass | PixelTypes.Argb)]
+        public void CopyStretchedRGBTo_WithOffset<TColor>(TestImageProvider<TColor> provider) 
+            where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            var src = provider.GetImage();
+            
+            PixelArea<TColor> area = new PixelArea<TColor>(8, 8, ComponentOrder.XYZ);
+            var dest = provider.Factory.CreateImage(8, 8);
+
+            using (var s = src.Lock())
+            {
+                using (var d = dest.Lock())
+                {
+                    s.CopyRGBBytesStretchedTo(area, 7, 6);
+                    d.CopyFrom(area, 0, 0);
+
+                    Assert.Equal(s[6, 7], d[0, 0]);
+                    Assert.Equal(s[6, 8], d[0, 1]);
+                    Assert.Equal(s[7, 8], d[1, 1]);
+
+                    Assert.Equal(s[6, 9], d[0, 2]);
+                    Assert.Equal(s[6, 9], d[0, 3]);
+                    Assert.Equal(s[6, 9], d[0, 7]);
+
+                    Assert.Equal(s[7, 9], d[1, 2]);
+                    Assert.Equal(s[7, 9], d[1, 3]);
+                    Assert.Equal(s[7, 9], d[1, 7]);
+
+                    Assert.Equal(s[9, 9], d[3, 2]);
+                    Assert.Equal(s[9, 9], d[3, 3]);
+                    Assert.Equal(s[9, 9], d[3, 7]);
+
+                    Assert.Equal(s[9, 7], d[3, 0]);
+                    Assert.Equal(s[9, 7], d[4, 0]);
+                    Assert.Equal(s[9, 7], d[7, 0]);
+
+                    Assert.Equal(s[9, 9], d[3, 2]);
+                    Assert.Equal(s[9, 9], d[4, 2]);
+                    Assert.Equal(s[9, 9], d[7, 2]);
+
+                    Assert.Equal(s[9, 9], d[4, 3]);
+                    Assert.Equal(s[9, 9], d[7, 7]);
+                }
+            }
+        }
     }
 }