Fix some warnings

src/ImageSharp/Formats/WebP/LosslessUtils.cs

@@ -1,3 +1,6 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using System;
 using System.Runtime.InteropServices;
 
@@ -132,6 +135,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 newBlue += ColorTransformDelta(m.GreenToBlue, (sbyte)green);
                 newBlue += ColorTransformDelta(m.RedToBlue, (sbyte)newRed);
                 newBlue &= 0xff;
+
                 // uint pixelValue = (uint)((argb & 0xff00ff00u) | (newRed << 16) | newBlue);
                 pixelData[i] = (uint)((argb & 0xff00ff00u) | (newRed << 16) | newBlue);
             }
@@ -162,6 +166,28 @@ namespace SixLabors.ImageSharp.Formats.WebP
             return newColorMap;
         }
 
+        public static void PredictorInverseTransform(Vp8LTransform transform, uint[] pixelData)
+        {
+            int processedPixels = 0;
+            int yStart = 0;
+            int width = transform.XSize;
+
+            // PredictorAdd0(in, NULL, 1, out);
+            PredictorAdd1(pixelData, width - 1);
+            processedPixels += width;
+            yStart++;
+
+            int y = yStart;
+            int tileWidth = 1 << transform.Bits;
+            int mask = tileWidth - 1;
+            int tilesPerRow = SubSampleSize(width, transform.Bits);
+        }
+
+        private static uint Predictor0C(uint left, uint[] top)
+        {
+            return WebPConstants.ArgbBlack;
+        }
+
         /// <summary>
         /// Computes sampled size of 'size' when sampling using 'sampling bits'.
         /// </summary>

src/ImageSharp/Formats/WebP/Vp8LBitReader.cs

@@ -25,7 +25,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// </summary>
         private const int VP8L_WBITS = 32;
 
-        private uint[] kBitMask =
+        private readonly uint[] kBitMask =
         {
             0,
             0x000001, 0x000003, 0x000007, 0x00000f,
@@ -80,7 +80,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// <summary>
         /// Buffer length.
         /// </summary>
-        private long len;
+        private readonly long len;
 
         /// <summary>
         /// Byte position in buffer.

src/ImageSharp/Formats/WebP/WebPConstants.cs

@@ -52,54 +52,57 @@ namespace SixLabors.ImageSharp.Formats.WebP
         /// <summary>
         /// Signature byte which identifies a VP8L header.
         /// </summary>
-        public static byte Vp8LMagicByte = 0x2F;
+        public const byte Vp8LMagicByte = 0x2F;
 
         /// <summary>
         /// 3 bits reserved for version.
         /// </summary>
-        public static int Vp8LVersionBits = 3;
+        public const int Vp8LVersionBits = 3;
 
         /// <summary>
         /// Bits for width and height infos of a VPL8 image.
         /// </summary>
-        public static int Vp8LImageSizeBits = 14;
+        public const int Vp8LImageSizeBits = 14;
 
         /// <summary>
         /// Maximum number of color cache bits.
         /// </summary>
-        public static int MaxColorCacheBits = 11;
+        public const int MaxColorCacheBits = 11;
 
         /// <summary>
         /// The maximum number of allowed transforms in a bitstream.
         /// </summary>
-        public static int MaxNumberOfTransforms = 4;
+        public const int MaxNumberOfTransforms = 4;
 
-        public static int MaxAllowedCodeLength = 15;
+        public const int MaxAllowedCodeLength = 15;
 
-        public static int DefaultCodeLength = 8;
+        public const int DefaultCodeLength = 8;
 
-        public static int HuffmanCodesPerMetaCode = 5;
+        public const int HuffmanCodesPerMetaCode = 5;
 
-        public static int NumLiteralCodes = 256;
+        public const uint ArgbBlack = 0xff000000;
 
-        public static int NumLengthCodes = 24;
+        public const int NumLiteralCodes = 256;
 
-        public static int NumDistanceCodes = 40;
+        public const int NumLengthCodes = 24;
 
-        public static int LengthTableBits = 7;
+        public const int NumDistanceCodes = 40;
 
-        public static uint kCodeLengthLiterals = 16;
+        public const int LengthTableBits = 7;
 
-        public static int kCodeLengthRepeatCode = 16;
+        public const uint KCodeLengthLiterals = 16;
 
-        public static int[] kCodeLengthExtraBits = { 2, 3, 7 };
+        public const int KCodeLengthRepeatCode = 16;
 
-        public static int[] kCodeLengthRepeatOffsets = { 3, 3, 11 };
+        public static readonly int[] KCodeLengthExtraBits = { 2, 3, 7 };
 
-        public static int[] kAlphabetSize = {
-                                                NumLiteralCodes + NumLengthCodes,
-                                                NumLiteralCodes, NumLiteralCodes, NumLiteralCodes,
-                                                NumDistanceCodes
-                                            };
+        public static readonly int[] KCodeLengthRepeatOffsets = { 3, 3, 11 };
+
+        public static readonly int[] KAlphabetSize =
+        {
+                                                         NumLiteralCodes + NumLengthCodes,
+                                                         NumLiteralCodes, NumLiteralCodes, NumLiteralCodes,
+                                                         NumDistanceCodes
+        };
     }
 }

src/ImageSharp/Formats/WebP/WebPImageInfo.cs

@@ -16,7 +16,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
         public int Height { get; set; }
 
         /// <summary>
-        /// Gets or sets whether this image uses a lossless compression.
+        /// Gets or sets a value indicating whether this image uses a lossless compression.
         /// </summary>
         public bool IsLossLess { get; set; }
 
@@ -26,12 +26,11 @@ namespace SixLabors.ImageSharp.Formats.WebP
         public WebPFeatures Features { get; set; }
 
         /// <summary>
-        /// The bytes of the image payload.
+        /// Gets or sets the bytes of the image payload.
         /// </summary>
         public uint ImageDataSize { get; set; }
 
-        // TODO: not sure if the bitreader is in the right place here, but for the sake of simplicity it will stay here for now.
-        // Will be refactored later. 
+        // TODO: not sure if the bitreader is in the right place here, but for the sake of simplicity it will stay here for now. Will be refactored later.
         public Vp8LBitReader Vp9LBitReader { get; set; }
     }
 }

src/ImageSharp/Formats/WebP/WebPLosslessDecoder.cs

@@ -368,7 +368,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
             // Find maximum alphabet size for the hTree group.
             for (int j = 0; j < WebPConstants.HuffmanCodesPerMetaCode; j++)
             {
-                int alphabetSize = WebPConstants.kAlphabetSize[j];
+                int alphabetSize = WebPConstants.KAlphabetSize[j];
                 if (j == 0 && colorCacheBits > 0)
                 {
                     alphabetSize += 1 << colorCacheBits;
@@ -394,7 +394,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 var codeLengths = new int[maxAlphabetSize];
                 for (int j = 0; j < WebPConstants.HuffmanCodesPerMetaCode; j++)
                 {
-                    int alphabetSize = WebPConstants.kAlphabetSize[j];
+                    int alphabetSize = WebPConstants.KAlphabetSize[j];
                     if (j == 0 && colorCacheBits > 0)
                     {
                         alphabetSize += 1 << colorCacheBits;
@@ -548,7 +548,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 HuffmanCode huffmanCode = table[idx];
                 this.bitReader.AdvanceBitPosition(huffmanCode.BitsUsed);
                 uint codeLen = huffmanCode.Value;
-                if (codeLen < WebPConstants.kCodeLengthLiterals)
+                if (codeLen < WebPConstants.KCodeLengthLiterals)
                 {
                     codeLengths[symbol++] = (int)codeLen;
                     if (codeLen != 0)
@@ -558,10 +558,10 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 }
                 else
                 {
-                    bool usePrev = codeLen == WebPConstants.kCodeLengthRepeatCode;
-                    uint slot = codeLen - WebPConstants.kCodeLengthLiterals;
-                    int extraBits = WebPConstants.kCodeLengthExtraBits[slot];
-                    int repeatOffset = WebPConstants.kCodeLengthRepeatOffsets[slot];
+                    bool usePrev = codeLen == WebPConstants.KCodeLengthRepeatCode;
+                    uint slot = codeLen - WebPConstants.KCodeLengthLiterals;
+                    int extraBits = WebPConstants.KCodeLengthExtraBits[slot];
+                    int repeatOffset = WebPConstants.KCodeLengthRepeatOffsets[slot];
                     int repeat = (int)(this.bitReader.ReadBits(extraBits) + repeatOffset);
                     if (symbol + repeat > numSymbols)
                     {
@@ -637,7 +637,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
                 switch (transformType)
                 {
                     case Vp8LTransformType.PredictorTransform:
-                        // LosslessUtils.PredictorInverseTransform(transforms[i], pixelData);
+                        LosslessUtils.PredictorInverseTransform(transforms[i], pixelData);
                         break;
                     case Vp8LTransformType.SubtractGreen:
                         LosslessUtils.AddGreenToBlueAndRed(pixelData);

src/ImageSharp/Formats/WebP/WebPLossyDecoder.cs

@@ -51,7 +51,7 @@ namespace SixLabors.ImageSharp.Formats.WebP
             }
 
             byte version = (byte)((bitReader.ReadBit() ? 2 : 0) | (bitReader.ReadBit() ? 1 : 0));
-            (ReconstructionFilter rec, LoopFilter loop) = DecodeVersion(version);
+            (ReconstructionFilter rec, LoopFilter loop) = this.DecodeVersion(version);
 
             bool isShowFrame = bitReader.ReadBit();
 

src/ImageSharp/Formats/WebP/WebPMetadata.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System.Collections;
 using System.Collections.Generic;
 
 namespace SixLabors.ImageSharp.Formats.WebP
@@ -28,9 +27,6 @@ namespace SixLabors.ImageSharp.Formats.WebP
             this.Format = other.Format;
         }
 
-        /// <inheritdoc/>
-        public IDeepCloneable DeepClone() => new WebPMetadata(this);
-
         /// <summary>
         /// The webp format used. Either lossless or lossy.
         /// </summary>
@@ -42,8 +38,11 @@ namespace SixLabors.ImageSharp.Formats.WebP
         public Queue<WebPChunkType> ChunkTypes { get; set; } = new Queue<WebPChunkType>();
 
         /// <summary>
-        /// Indicates, if the webp file contains a animation.
+        /// Gets or sets a value indicating whether the webp file contains a animation.
         /// </summary>
         public bool Animated { get; set; } = false;
+
+        /// <inheritdoc/>
+        public IDeepCloneable DeepClone() => new WebPMetadata(this);
     }
 }