From 4ec66a27625eb104a0bca30cafbe4c44c239f7db Mon Sep 17 00:00:00 2001
From: Brian Popow <popow@gmx.de>
Date: Wed, 20 Oct 2021 18:19:57 +0200
Subject: [PATCH] Use pattern matching

---
 src/ImageSharp/Formats/Webp/AlphaDecoder.cs       |  4 ++--
 .../Formats/Webp/BitWriter/Vp8BitWriter.cs        |  2 +-
 .../Formats/Webp/Lossless/Vp8LEncoder.cs          | 15 ++++++---------
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/src/ImageSharp/Formats/Webp/AlphaDecoder.cs b/src/ImageSharp/Formats/Webp/AlphaDecoder.cs
index c2a6a261f..e63cd27b5 100644
--- a/src/ImageSharp/Formats/Webp/AlphaDecoder.cs
+++ b/src/ImageSharp/Formats/Webp/AlphaDecoder.cs
@@ -38,7 +38,7 @@ namespace SixLabors.ImageSharp.Formats.Webp
             int totalPixels = width * height;
 
             var compression = (WebpAlphaCompressionMethod)(alphaChunkHeader & 0x03);
-            if (compression != WebpAlphaCompressionMethod.NoCompression && compression != WebpAlphaCompressionMethod.WebpLosslessCompression)
+            if (compression is not WebpAlphaCompressionMethod.NoCompression and not WebpAlphaCompressionMethod.WebpLosslessCompression)
             {
                 WebpThrowHelper.ThrowImageFormatException($"unexpected alpha compression method {compression} found");
             }
@@ -47,7 +47,7 @@ namespace SixLabors.ImageSharp.Formats.Webp
 
             // The filtering method used. Only values between 0 and 3 are valid.
             int filter = (alphaChunkHeader >> 2) & 0x03;
-            if (filter < (int)WebpAlphaFilterType.None || filter > (int)WebpAlphaFilterType.Gradient)
+            if (filter is < (int)WebpAlphaFilterType.None or > (int)WebpAlphaFilterType.Gradient)
             {
                 WebpThrowHelper.ThrowImageFormatException($"unexpected alpha filter method {filter} found");
             }
diff --git a/src/ImageSharp/Formats/Webp/BitWriter/Vp8BitWriter.cs b/src/ImageSharp/Formats/Webp/BitWriter/Vp8BitWriter.cs
index 76766f67e..7628247fd 100644
--- a/src/ImageSharp/Formats/Webp/BitWriter/Vp8BitWriter.cs
+++ b/src/ImageSharp/Formats/Webp/BitWriter/Vp8BitWriter.cs
@@ -221,7 +221,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.BitWriter
 
         public void PutI16Mode(int mode)
         {
-            if (this.PutBit(mode == TM_PRED || mode == H_PRED, 156))
+            if (this.PutBit(mode is TM_PRED or H_PRED, 156))
             {
                 this.PutBit(mode == TM_PRED, 128);    // TM or HE
             }
diff --git a/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs b/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs
index c95b8e362..2ebd3a270 100644
--- a/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs
+++ b/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs
@@ -289,12 +289,9 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             {
                 bgra.CopyTo(encodedData);
                 bool useCache = true;
-                this.UsePalette = crunchConfig.EntropyIdx == EntropyIx.Palette ||
-                                  crunchConfig.EntropyIdx == EntropyIx.PaletteAndSpatial;
-                this.UseSubtractGreenTransform = crunchConfig.EntropyIdx == EntropyIx.SubGreen ||
-                                                 crunchConfig.EntropyIdx == EntropyIx.SpatialSubGreen;
-                this.UsePredictorTransform = crunchConfig.EntropyIdx == EntropyIx.Spatial ||
-                                             crunchConfig.EntropyIdx == EntropyIx.SpatialSubGreen;
+                this.UsePalette = crunchConfig.EntropyIdx is EntropyIx.Palette or EntropyIx.PaletteAndSpatial;
+                this.UseSubtractGreenTransform = crunchConfig.EntropyIdx is EntropyIx.SubGreen or EntropyIx.SpatialSubGreen;
+                this.UsePredictorTransform = crunchConfig.EntropyIdx is EntropyIx.Spatial or EntropyIx.SpatialSubGreen;
                 if (lowEffort)
                 {
                     this.UseCrossColorTransform = false;
@@ -427,7 +424,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             this.TransformBits = GetTransformBits(this.method, this.HistoBits);
 
             // Try out multiple LZ77 on images with few colors.
-            int nlz77s = this.PaletteSize > 0 && this.PaletteSize <= 16 ? 2 : 1;
+            int nlz77s = this.PaletteSize is > 0 and <= 16 ? 2 : 1;
             EntropyIx entropyIdx = this.AnalyzeEntropy(bgra, width, height, usePalette, this.PaletteSize, this.TransformBits, out redAndBlueAlwaysZero);
 
             bool doNotCache = false;
@@ -863,7 +860,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             while (i-- > 0)
             {
                 int ix = tokens[i].Code;
-                if (ix == 0 || ix == 17 || ix == 18)
+                if (ix is 0 or 17 or 18)
                 {
                     trimmedLength--;   // Discount trailing zeros.
                     trailingZeroBits += codeLengthBitDepth[ix];
@@ -1345,7 +1342,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                     }
                 }
 
-                if (i == 0 || i == 1 || i == 2)
+                if (i is 0 or 1 or 2)
                 {
                     ApplyPaletteFor(width, height, palette, i, src, srcStride, dst, dstStride, tmpRow, buffer, xBits);
                 }