Fix issue #1594

src/ImageSharp/Formats/WebP/Lossless/WebpLosslessDecoder.cs

@@ -102,7 +102,7 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Webp.Lossless
             {
                 this.DecodeImageStream(decoder, width, height, true);
                 this.DecodeImageData(decoder, decoder.Pixels.Memory.Span);
-                this.DecodePixelValues(decoder, pixels);
+                this.DecodePixelValues(decoder, pixels, width, height);
             }
         }
 
@@ -185,18 +185,17 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Webp.Lossless
             return pixelData;
         }
 
-        private void DecodePixelValues<TPixel>(Vp8LDecoder decoder, Buffer2D<TPixel> pixels)
+        private void DecodePixelValues<TPixel>(Vp8LDecoder decoder, Buffer2D<TPixel> pixels, int width, int height)
             where TPixel : unmanaged, IPixel<TPixel>
         {
             Span<uint> pixelData = decoder.Pixels.GetSpan();
-            int width = decoder.Width;
 
             // Apply reverse transformations, if any are present.
             ApplyInverseTransforms(decoder, pixelData, this.memoryAllocator);
 
             Span<byte> pixelDataAsBytes = MemoryMarshal.Cast<uint, byte>(pixelData);
             int bytesPerRow = width * 4;
-            for (int y = 0; y < decoder.Height; y++)
+            for (int y = 0; y < height; y++)
             {
                 Span<byte> rowAsBytes = pixelDataAsBytes.Slice(y * bytesPerRow, bytesPerRow);
                 Span<TPixel> pixelRow = pixels.GetRowSpan(y);
@@ -859,7 +858,7 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Webp.Lossless
 
         /// <summary>
         /// Decodes the next Huffman code from the bit-stream.
-        /// FillBitWindow(br) needs to be called at minimum every second call to ReadSymbol, in order to pre-fetch enough bits.
+        /// FillBitWindow() needs to be called at minimum every second call to ReadSymbol, in order to pre-fetch enough bits.
         /// </summary>
         private uint ReadSymbol(Span<HuffmanCode> table)
         {

tests/ImageSharp.Tests/Formats/WebP/WebpDecoderTests.cs

@@ -323,7 +323,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Webp
         [WithFile(Lossless.LossLessCorruptImage1, PixelTypes.Rgba32)]
         [WithFile(Lossless.LossLessCorruptImage2, PixelTypes.Rgba32)]
         [WithFile(Lossless.LossLessCorruptImage4, PixelTypes.Rgba32)]
-        public void WebpDecoder_CanDecodeLosslessWithIssues<TPixel>(TestImageProvider<TPixel> provider)
+        public void WebpDecoder_CanDecode_Lossless_WithIssues<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel>
         {
             // Just make sure no exception is thrown. The reference decoder fails to load the image.
@@ -333,6 +333,19 @@ namespace SixLabors.ImageSharp.Tests.Formats.Webp
             }
         }
 
+        // https://github.com/SixLabors/ImageSharp/issues/1594
+        [Theory]
+        [WithFile(Lossy.Issue1594, PixelTypes.Rgba32)]
+        public void WebpDecoder_CanDecode_Issue1594<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage(WebpDecoder))
+            {
+                image.DebugSave(provider);
+                image.CompareToOriginal(provider, ReferenceDecoder);
+            }
+        }
+
         [Theory]
         [WithFile(Lossless.LossLessCorruptImage3, PixelTypes.Rgba32)]
         public void WebpDecoder_ThrowImageFormatException_OnInvalidImages<TPixel>(TestImageProvider<TPixel> provider)

tests/ImageSharp.Tests/TestImages.cs

@@ -647,6 +647,9 @@ namespace SixLabors.ImageSharp.Tests
                 public const string AlphaCompressedGradientFilter = "WebP/alpha_filter_3_method_1.webp";
                 public const string AlphaThinkingSmiley = "WebP/1602311202.webp";
                 public const string AlphaSticker = "WebP/sticker.webp";
+
+                // Issues
+                public const string Issue1594 = "Webp/issues/Issue1594.webp";
             }
         }
     }

tests/Images/Input/WebP/issues/Issue1594.webp

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:37413b1a89ba7d42cdfe98196775c2ddc2f8f4d143f6fc65218dc288423b7177
+size 62