From b6e09b5bb43369799a2b0dbb8c69230437f7e352 Mon Sep 17 00:00:00 2001
From: Brian Popow <popow@gmx.de>
Date: Thu, 26 May 2022 18:03:48 +0200
Subject: [PATCH] Add support for decoding tiff with webp compressed data

---
 .../Decompressors/WebpTiffCompression.cs      | 55 +++++++++++++++++++
 .../Compression/TiffDecoderCompressionType.cs |  5 ++
 .../Compression/TiffDecompressorsFactory.cs   |  4 ++
 .../Formats/Tiff/Constants/TiffCompression.cs |  8 +++
 .../Formats/Tiff/TiffDecoderOptionsParser.cs  |  6 ++
 5 files changed, 78 insertions(+)
 create mode 100644 src/ImageSharp/Formats/Tiff/Compression/Decompressors/WebpTiffCompression.cs

diff --git a/src/ImageSharp/Formats/Tiff/Compression/Decompressors/WebpTiffCompression.cs b/src/ImageSharp/Formats/Tiff/Compression/Decompressors/WebpTiffCompression.cs
new file mode 100644
index 0000000000..8cceecbc18
--- /dev/null
+++ b/src/ImageSharp/Formats/Tiff/Compression/Decompressors/WebpTiffCompression.cs
@@ -0,0 +1,55 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Runtime.InteropServices;
+using SixLabors.ImageSharp.Formats.Tiff.Constants;
+using SixLabors.ImageSharp.Formats.Webp;
+using SixLabors.ImageSharp.IO;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
+{
+    /// <summary>
+    /// Class to handle cases where TIFF image data is compressed as a webp stream.
+    /// </summary>
+    internal class WebpTiffCompression : TiffBaseDecompressor
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="WebpTiffCompression"/> class.
+        /// </summary>
+        /// <param name="memoryAllocator">The memory allocator.</param>
+        /// <param name="width">The width of the image.</param>
+        /// <param name="bitsPerPixel">The bits per pixel.</param>
+        /// <param name="predictor">The predictor.</param>
+        public WebpTiffCompression(MemoryAllocator memoryAllocator, int width, int bitsPerPixel, TiffPredictor predictor = TiffPredictor.None)
+            : base(memoryAllocator, width, bitsPerPixel, predictor)
+        {
+        }
+
+        /// <inheritdoc/>
+        protected override void Decompress(BufferedReadStream stream, int byteCount, int stripHeight, Span<byte> buffer)
+        {
+            using var image = Image.Load<Rgb24>(stream, new WebpDecoder());
+            CopyImageBytesToBuffer(buffer, image.Frames.RootFrame.PixelBuffer);
+        }
+
+        private static void CopyImageBytesToBuffer(Span<byte> buffer, Buffer2D<Rgb24> pixelBuffer)
+        {
+            int offset = 0;
+            for (int y = 0; y < pixelBuffer.Height; y++)
+            {
+                Span<Rgb24> pixelRowSpan = pixelBuffer.DangerousGetRowSpan(y);
+                Span<byte> rgbBytes = MemoryMarshal.AsBytes(pixelRowSpan);
+                rgbBytes.CopyTo(buffer.Slice(offset));
+                offset += rgbBytes.Length;
+            }
+        }
+
+        /// <inheritdoc/>
+        protected override void Dispose(bool disposing)
+        {
+        }
+    }
+}
diff --git a/src/ImageSharp/Formats/Tiff/Compression/TiffDecoderCompressionType.cs b/src/ImageSharp/Formats/Tiff/Compression/TiffDecoderCompressionType.cs
index d8843c1078..77d77f98f5 100644
--- a/src/ImageSharp/Formats/Tiff/Compression/TiffDecoderCompressionType.cs
+++ b/src/ImageSharp/Formats/Tiff/Compression/TiffDecoderCompressionType.cs
@@ -47,5 +47,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression
         /// The image data is compressed as a JPEG stream.
         /// </summary>
         Jpeg = 7,
+
+        /// <summary>
+        /// The image data is compressed as a WEBP stream.
+        /// </summary>
+        Webp = 8,
     }
 }
diff --git a/src/ImageSharp/Formats/Tiff/Compression/TiffDecompressorsFactory.cs b/src/ImageSharp/Formats/Tiff/Compression/TiffDecompressorsFactory.cs
index a7e2e276bd..0e526f3d93 100644
--- a/src/ImageSharp/Formats/Tiff/Compression/TiffDecompressorsFactory.cs
+++ b/src/ImageSharp/Formats/Tiff/Compression/TiffDecompressorsFactory.cs
@@ -60,6 +60,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression
                     DebugGuard.IsTrue(predictor == TiffPredictor.None, "Predictor should only be used with lzw or deflate compression");
                     return new JpegTiffCompression(configuration, allocator, width, bitsPerPixel, jpegTables, photometricInterpretation);
 
+                case TiffDecoderCompressionType.Webp:
+                    DebugGuard.IsTrue(predictor == TiffPredictor.None, "Predictor should only be used with lzw or deflate compression");
+                    return new WebpTiffCompression(allocator, width, bitsPerPixel);
+
                 default:
                     throw TiffThrowHelper.NotSupportedDecompressor(nameof(method));
             }
diff --git a/src/ImageSharp/Formats/Tiff/Constants/TiffCompression.cs b/src/ImageSharp/Formats/Tiff/Constants/TiffCompression.cs
index 765f2c237d..0591c24dd5 100644
--- a/src/ImageSharp/Formats/Tiff/Constants/TiffCompression.cs
+++ b/src/ImageSharp/Formats/Tiff/Constants/TiffCompression.cs
@@ -103,5 +103,13 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Constants
         /// if this is chosen.
         /// </summary>
         OldDeflate = 32946,
+
+        /// <summary>
+        /// Pixel data is compressed with webp encoder.
+        ///
+        /// Note: The TIFF encoder does not support this compression and will default to use no compression instead,
+        /// if this is chosen.
+        /// </summary>
+        Webp = 50001,
     }
 }
diff --git a/src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs b/src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs
index 6d99fed3e1..1d52b95ac6 100644
--- a/src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs
+++ b/src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs
@@ -470,6 +470,12 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                     break;
                 }
 
+                case TiffCompression.Webp:
+                {
+                    options.CompressionType = TiffDecoderCompressionType.Webp;
+                    break;
+                }
+
                 default:
                 {
                     TiffThrowHelper.ThrowNotSupported($"The specified TIFF compression format '{compression}' is not supported");