From f4cc295e4cd4495e6491a5eef4e9e5c7efc995ae Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 12:15:08 +1000
Subject: [PATCH 01/18] Decode tile rows directly. Fix #2873

---
 .../Formats/Tiff/TiffDecoderCore.cs           | 35 +++++++++----------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs b/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs
index 96e6d2a89d..f16ffd0da1 100644
--- a/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs
+++ b/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs
@@ -608,7 +608,7 @@ private void DecodeTilesPlanar<TPixel>(
     }
 
     /// <summary>
-    /// Decodes the image data for Tiff's which arrange the pixel data in tiles and the chunky configuration.
+    /// Decodes the image data for TIFFs which arrange the pixel data in tiles and the chunky configuration.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
     /// <param name="frame">The image frame to decode into.</param>
@@ -634,14 +634,10 @@ private void DecodeTilesChunky<TPixel>(
         int width = pixels.Width;
         int height = pixels.Height;
         int bitsPerPixel = this.BitsPerPixel;
-
-        int bytesPerRow = RoundUpToMultipleOfEight(width * bitsPerPixel);
         int bytesPerTileRow = RoundUpToMultipleOfEight(tileWidth * bitsPerPixel);
-        int uncompressedTilesSize = bytesPerTileRow * tileLength;
-        using IMemoryOwner<byte> tileBuffer = this.memoryAllocator.Allocate<byte>(uncompressedTilesSize, AllocationOptions.Clean);
-        using IMemoryOwner<byte> uncompressedPixelBuffer = this.memoryAllocator.Allocate<byte>(tilesDown * tileLength * bytesPerRow, AllocationOptions.Clean);
+
+        using IMemoryOwner<byte> tileBuffer = this.memoryAllocator.Allocate<byte>(bytesPerTileRow * tileLength, AllocationOptions.Clean);
         Span<byte> tileBufferSpan = tileBuffer.GetSpan();
-        Span<byte> uncompressedPixelBufferSpan = uncompressedPixelBuffer.GetSpan();
 
         using TiffBaseDecompressor decompressor = this.CreateDecompressor<TPixel>(frame.Width, bitsPerPixel);
         TiffBaseColorDecoder<TPixel> colorDecoder = this.CreateChunkyColorDecoder<TPixel>();
@@ -649,13 +645,15 @@ private void DecodeTilesChunky<TPixel>(
         int tileIndex = 0;
         for (int tileY = 0; tileY < tilesDown; tileY++)
         {
-            int remainingPixelsInRow = width;
+            int rowStartY = tileY * tileLength;
+            int rowEndY = Math.Min(rowStartY + tileLength, height);
+
             for (int tileX = 0; tileX < tilesAcross; tileX++)
             {
                 cancellationToken.ThrowIfCancellationRequested();
 
-                int uncompressedPixelBufferOffset = tileY * tileLength * bytesPerRow;
                 bool isLastHorizontalTile = tileX == tilesAcross - 1;
+                int remainingPixelsInRow = width - (tileX * tileWidth);
 
                 decompressor.Decompress(
                     this.inputStream,
@@ -666,22 +664,23 @@ private void DecodeTilesChunky<TPixel>(
                     cancellationToken);
 
                 int tileBufferOffset = 0;
-                uncompressedPixelBufferOffset += bytesPerTileRow * tileX;
-                int bytesToCopy = isLastHorizontalTile ? RoundUpToMultipleOfEight(bitsPerPixel * remainingPixelsInRow) : bytesPerTileRow;
-                for (int y = 0; y < tileLength; y++)
+                for (int y = rowStartY; y < rowEndY; y++)
                 {
-                    Span<byte> uncompressedPixelRow = uncompressedPixelBufferSpan.Slice(uncompressedPixelBufferOffset, bytesToCopy);
-                    tileBufferSpan.Slice(tileBufferOffset, bytesToCopy).CopyTo(uncompressedPixelRow);
+                    int bytesToCopy = isLastHorizontalTile ? RoundUpToMultipleOfEight(bitsPerPixel * remainingPixelsInRow) : bytesPerTileRow;
+                    ReadOnlySpan<byte> tileRowSpan = tileBufferSpan.Slice(tileBufferOffset, bytesToCopy);
+
+                    // Decode the tile row directly into the pixel buffer.
+                    int left = tileX * tileWidth;
+                    int rowWidth = Math.Min(tileWidth, remainingPixelsInRow);
+
+                    colorDecoder.Decode(tileRowSpan, pixels, left, y, rowWidth, 1);
+
                     tileBufferOffset += bytesPerTileRow;
-                    uncompressedPixelBufferOffset += bytesPerRow;
                 }
 
-                remainingPixelsInRow -= tileWidth;
                 tileIndex++;
             }
         }
-
-        colorDecoder.Decode(uncompressedPixelBufferSpan, pixels, 0, 0, width, height);
     }
 
     private TiffBaseColorDecoder<TPixel> CreateChunkyColorDecoder<TPixel>()

From 80b336bd0f62ae758d786b7de867ac7a0005b4bb Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 12:19:11 +1000
Subject: [PATCH 02/18] Optimize

---
 src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs b/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs
index f16ffd0da1..18535d1e37 100644
--- a/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs
+++ b/src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs
@@ -664,17 +664,15 @@ private void DecodeTilesChunky<TPixel>(
                     cancellationToken);
 
                 int tileBufferOffset = 0;
+                int bytesToCopy = isLastHorizontalTile ? RoundUpToMultipleOfEight(bitsPerPixel * remainingPixelsInRow) : bytesPerTileRow;
+                int rowWidth = Math.Min(tileWidth, remainingPixelsInRow);
+                int left = tileX * tileWidth;
+
                 for (int y = rowStartY; y < rowEndY; y++)
                 {
-                    int bytesToCopy = isLastHorizontalTile ? RoundUpToMultipleOfEight(bitsPerPixel * remainingPixelsInRow) : bytesPerTileRow;
-                    ReadOnlySpan<byte> tileRowSpan = tileBufferSpan.Slice(tileBufferOffset, bytesToCopy);
-
                     // Decode the tile row directly into the pixel buffer.
-                    int left = tileX * tileWidth;
-                    int rowWidth = Math.Min(tileWidth, remainingPixelsInRow);
-
+                    ReadOnlySpan<byte> tileRowSpan = tileBufferSpan.Slice(tileBufferOffset, bytesToCopy);
                     colorDecoder.Decode(tileRowSpan, pixels, left, y, rowWidth, 1);
-
                     tileBufferOffset += bytesPerTileRow;
                 }
 

From fcaef778a9924b07e4c0173fe678f2c3cd6b9f89 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 13:25:24 +1000
Subject: [PATCH 03/18] Fix CI build errors.

---
 .github/workflows/build-and-test.yml         | 2 +-
 .github/workflows/code-coverage.yml          | 3 +++
 src/ImageSharp/Formats/Png/PngThrowHelper.cs | 4 ++--
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index e17b8d724e..d0e2f91265 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -67,7 +67,7 @@ jobs:
 
     steps:
       - name: Install libgdi+, which is required for tests running on ubuntu
-        if: ${{ matrix.options.os == 'buildjet-4vcpu-ubuntu-2204-arm' }}
+        if: ${{ contains(matrix.options.os, 'ubuntu') }}
         run: sudo apt-get -y install libgdiplus libgif-dev libglib2.0-dev libcairo2-dev libtiff-dev libexif-dev
 
       - name: Git Config
diff --git a/.github/workflows/code-coverage.yml b/.github/workflows/code-coverage.yml
index e551afbd6d..b4038e520d 100644
--- a/.github/workflows/code-coverage.yml
+++ b/.github/workflows/code-coverage.yml
@@ -17,6 +17,9 @@ jobs:
     runs-on: ${{matrix.options.os}}
 
     steps:
+      - name: Install libgdi+, which is required for tests running on ubuntu
+        run: sudo apt-get -y install libgdiplus libgif-dev libglib2.0-dev libcairo2-dev libtiff-dev libexif-dev
+
       - name: Git Config
         shell: bash
         run: |
diff --git a/src/ImageSharp/Formats/Png/PngThrowHelper.cs b/src/ImageSharp/Formats/Png/PngThrowHelper.cs
index 0552e9a79e..bb21f348f3 100644
--- a/src/ImageSharp/Formats/Png/PngThrowHelper.cs
+++ b/src/ImageSharp/Formats/Png/PngThrowHelper.cs
@@ -40,11 +40,11 @@ public static void ThrowInvalidImageContentException(string errorMessage, Except
     public static void ThrowInvalidChunkCrc(string chunkTypeName) => throw new InvalidImageContentException($"CRC Error. PNG {chunkTypeName} chunk is corrupt!");
 
     [DoesNotReturn]
-    public static void ThrowInvalidParameter(object value, string message, [CallerArgumentExpression(nameof(value))] string name = "")
+    public static void ThrowInvalidParameter(object value, string message, [CallerArgumentExpression("value")] string name = "")
         => throw new NotSupportedException($"Invalid {name}. {message}. Was '{value}'.");
 
     [DoesNotReturn]
-    public static void ThrowInvalidParameter(object value1, object value2, string message, [CallerArgumentExpression(nameof(value1))] string name1 = "", [CallerArgumentExpression(nameof(value1))] string name2 = "")
+    public static void ThrowInvalidParameter(object value1, object value2, string message, [CallerArgumentExpression("value1")] string name1 = "", [CallerArgumentExpression("value2")] string name2 = "")
         => throw new NotSupportedException($"Invalid {name1} or {name2}. {message}. Was '{value1}' and '{value2}'.");
 
     [DoesNotReturn]

From b88f789ca04e59f3d8c5a5ac3ec19c952b158c6d Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 13:30:56 +1000
Subject: [PATCH 04/18] Don't use TF during build, just test it.

---
 ci-build.ps1                                 | 5 ++++-
 src/ImageSharp/Formats/Png/PngThrowHelper.cs | 4 ++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/ci-build.ps1 b/ci-build.ps1
index d45af6ff4d..d97cbbcb80 100644
--- a/ci-build.ps1
+++ b/ci-build.ps1
@@ -8,4 +8,7 @@ dotnet clean -c Release
 $repositoryUrl = "https://github.com/$env:GITHUB_REPOSITORY"
 
 # Building for a specific framework.
-dotnet build -c Release -f $targetFramework /p:RepositoryUrl=$repositoryUrl
+# dotnet build -c Release -f $targetFramework /p:RepositoryUrl=$repositoryUrl
+#
+# CI is now throwing build errors when none were present previously.
+dotnet build -c Release -f /p:RepositoryUrl=$repositoryUrl
diff --git a/src/ImageSharp/Formats/Png/PngThrowHelper.cs b/src/ImageSharp/Formats/Png/PngThrowHelper.cs
index bb21f348f3..8dc70e1d9a 100644
--- a/src/ImageSharp/Formats/Png/PngThrowHelper.cs
+++ b/src/ImageSharp/Formats/Png/PngThrowHelper.cs
@@ -40,11 +40,11 @@ public static void ThrowInvalidImageContentException(string errorMessage, Except
     public static void ThrowInvalidChunkCrc(string chunkTypeName) => throw new InvalidImageContentException($"CRC Error. PNG {chunkTypeName} chunk is corrupt!");
 
     [DoesNotReturn]
-    public static void ThrowInvalidParameter(object value, string message, [CallerArgumentExpression("value")] string name = "")
+    public static void ThrowInvalidParameter(object value, string message, [CallerArgumentExpression(nameof(value))] string name = "")
         => throw new NotSupportedException($"Invalid {name}. {message}. Was '{value}'.");
 
     [DoesNotReturn]
-    public static void ThrowInvalidParameter(object value1, object value2, string message, [CallerArgumentExpression("value1")] string name1 = "", [CallerArgumentExpression("value2")] string name2 = "")
+    public static void ThrowInvalidParameter(object value1, object value2, string message, [CallerArgumentExpression(nameof(value1))] string name1 = "", [CallerArgumentExpression(nameof(value2))] string name2 = "")
         => throw new NotSupportedException($"Invalid {name1} or {name2}. {message}. Was '{value1}' and '{value2}'.");
 
     [DoesNotReturn]

From 09ca511cccddabc1210d77e88a2eab5cc03bc56b Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 14:14:01 +1000
Subject: [PATCH 05/18] Try using setup-dotnet v4

---
 .github/workflows/build-and-test.yml | 4 ++--
 .github/workflows/code-coverage.yml  | 2 +-
 ci-build.ps1                         | 5 +----
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index d0e2f91265..5cf6d98068 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -109,14 +109,14 @@ jobs:
 
       - name: DotNet Setup
         if: ${{ matrix.options.sdk-preview != true }}
-        uses: actions/setup-dotnet@v3
+        uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
             6.0.x
 
       - name: DotNet Setup Preview
         if: ${{ matrix.options.sdk-preview == true }}
-        uses: actions/setup-dotnet@v3
+        uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
             7.0.x
diff --git a/.github/workflows/code-coverage.yml b/.github/workflows/code-coverage.yml
index b4038e520d..26e2013320 100644
--- a/.github/workflows/code-coverage.yml
+++ b/.github/workflows/code-coverage.yml
@@ -58,7 +58,7 @@ jobs:
           restore-keys: ${{ runner.os }}-nuget-
 
       - name: DotNet Setup
-        uses: actions/setup-dotnet@v3
+        uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
             6.0.x
diff --git a/ci-build.ps1 b/ci-build.ps1
index d97cbbcb80..d45af6ff4d 100644
--- a/ci-build.ps1
+++ b/ci-build.ps1
@@ -8,7 +8,4 @@ dotnet clean -c Release
 $repositoryUrl = "https://github.com/$env:GITHUB_REPOSITORY"
 
 # Building for a specific framework.
-# dotnet build -c Release -f $targetFramework /p:RepositoryUrl=$repositoryUrl
-#
-# CI is now throwing build errors when none were present previously.
-dotnet build -c Release -f /p:RepositoryUrl=$repositoryUrl
+dotnet build -c Release -f $targetFramework /p:RepositoryUrl=$repositoryUrl

From b350dbe74870ee9d1e77fd68be1ca76d72dba659 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 14:31:25 +1000
Subject: [PATCH 06/18] Try adding sdk install path to the global path

---
 .github/workflows/build-and-test.yml | 6 ++++++
 .github/workflows/code-coverage.yml  | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 5cf6d98068..c874fffc62 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -121,6 +121,12 @@ jobs:
           dotnet-version: |
             7.0.x
 
+      - name: Ensure Dotnet Path
+        run: echo "/usr/share/dotnet" >> $GITHUB_PATH
+
+      - name: Confirm .NET Version
+        run: dotnet --version  # This will now find dotnet in /usr/share/dotnet
+
       - name: DotNet Build
         if: ${{ matrix.options.sdk-preview != true }}
         shell: pwsh
diff --git a/.github/workflows/code-coverage.yml b/.github/workflows/code-coverage.yml
index 26e2013320..7fdb4bc826 100644
--- a/.github/workflows/code-coverage.yml
+++ b/.github/workflows/code-coverage.yml
@@ -63,6 +63,12 @@ jobs:
           dotnet-version: |
             6.0.x
 
+      - name: Ensure Dotnet Path
+        run: echo "/usr/share/dotnet" >> $GITHUB_PATH
+
+      - name: Confirm .NET Version
+        run: dotnet --version  # This will now find dotnet in /usr/share/dotnet
+
       - name: DotNet Build
         shell: pwsh
         run: ./ci-build.ps1 "${{matrix.options.framework}}"

From 80a1432d997398ec2ceae776303e4cf252033d90 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 14:39:16 +1000
Subject: [PATCH 07/18] Check the version within the powershell script

---
 .github/workflows/build-and-test.yml | 4 ++--
 .github/workflows/code-coverage.yml  | 4 ++--
 ci-build.ps1                         | 7 +++++++
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index c874fffc62..1edb5ae81e 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -121,10 +121,10 @@ jobs:
           dotnet-version: |
             7.0.x
 
-      - name: Ensure Dotnet Path
+      - name: Ensure DotNet Path
         run: echo "/usr/share/dotnet" >> $GITHUB_PATH
 
-      - name: Confirm .NET Version
+      - name: Confirm DotNet Version
         run: dotnet --version  # This will now find dotnet in /usr/share/dotnet
 
       - name: DotNet Build
diff --git a/.github/workflows/code-coverage.yml b/.github/workflows/code-coverage.yml
index 7fdb4bc826..da7d792cd8 100644
--- a/.github/workflows/code-coverage.yml
+++ b/.github/workflows/code-coverage.yml
@@ -63,10 +63,10 @@ jobs:
           dotnet-version: |
             6.0.x
 
-      - name: Ensure Dotnet Path
+      - name: Ensure DotNet Path
         run: echo "/usr/share/dotnet" >> $GITHUB_PATH
 
-      - name: Confirm .NET Version
+      - name: Confirm DotNet Version
         run: dotnet --version  # This will now find dotnet in /usr/share/dotnet
 
       - name: DotNet Build
diff --git a/ci-build.ps1 b/ci-build.ps1
index d45af6ff4d..74d4328e32 100644
--- a/ci-build.ps1
+++ b/ci-build.ps1
@@ -3,9 +3,16 @@ param(
   [string]$targetFramework
 )
 
+#$env:DOTNET_ROOT = "/usr/share/dotnet"
+#$env:PATH = "$env:DOTNET_ROOT" + [System.IO.Path]::PathSeparator + $env:PATH
+
+# Confirm dotnet version.
+dotnet --version
+
 dotnet clean -c Release
 
 $repositoryUrl = "https://github.com/$env:GITHUB_REPOSITORY"
 
+
 # Building for a specific framework.
 dotnet build -c Release -f $targetFramework /p:RepositoryUrl=$repositoryUrl

From 069ca5a11755ea5f3cc56f86fb8c98b01afd1d92 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 16:01:44 +1000
Subject: [PATCH 08/18] Add more debugging info

---
 .github/workflows/build-and-test.yml | 3 ++-
 ci-build.ps1                         | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 1edb5ae81e..83bab0d837 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -122,10 +122,11 @@ jobs:
             7.0.x
 
       - name: Ensure DotNet Path
+        if: ${{ matrix.options.os != 'windows-latest' }}
         run: echo "/usr/share/dotnet" >> $GITHUB_PATH
 
       - name: Confirm DotNet Version
-        run: dotnet --version  # This will now find dotnet in /usr/share/dotnet
+        run: dotnet --version
 
       - name: DotNet Build
         if: ${{ matrix.options.sdk-preview != true }}
diff --git a/ci-build.ps1 b/ci-build.ps1
index 74d4328e32..a98a5e27f8 100644
--- a/ci-build.ps1
+++ b/ci-build.ps1
@@ -3,8 +3,9 @@ param(
   [string]$targetFramework
 )
 
-#$env:DOTNET_ROOT = "/usr/share/dotnet"
-#$env:PATH = "$env:DOTNET_ROOT" + [System.IO.Path]::PathSeparator + $env:PATH
+Write-Output $env:PATH
+
+dotnet --list-sdks
 
 # Confirm dotnet version.
 dotnet --version
@@ -13,6 +14,5 @@ dotnet clean -c Release
 
 $repositoryUrl = "https://github.com/$env:GITHUB_REPOSITORY"
 
-
 # Building for a specific framework.
 dotnet build -c Release -f $targetFramework /p:RepositoryUrl=$repositoryUrl

From 12b8e0dc428e8a86ffaa4c7eb1df4b4795dc089e Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 16:06:55 +1000
Subject: [PATCH 09/18] Test windows only

---
 .github/workflows/build-and-test.yml | 68 ++++++++++++++--------------
 1 file changed, 34 insertions(+), 34 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 83bab0d837..ccab6d574b 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -19,40 +19,40 @@ jobs:
         isARM:
           - ${{ contains(github.event.pull_request.labels.*.name, 'arch:arm32') || contains(github.event.pull_request.labels.*.name, 'arch:arm64') }}
         options:
-          - os: ubuntu-latest
-            framework: net7.0
-            sdk: 7.0.x
-            sdk-preview: true
-            runtime: -x64
-            codecov: false
-          - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
-            framework: net7.0
-            sdk: 7.0.x
-            sdk-preview: true
-            runtime: -x64
-            codecov: false
-          - os: windows-latest
-            framework: net7.0
-            sdk: 7.0.x
-            sdk-preview: true
-            runtime: -x64
-            codecov: false
-          - os: buildjet-4vcpu-ubuntu-2204-arm
-            framework: net7.0
-            sdk: 7.0.x
-            sdk-preview: true
-            runtime: -x64
-            codecov: false
-          - os: ubuntu-latest
-            framework: net6.0
-            sdk: 6.0.x
-            runtime: -x64
-            codecov: false
-          - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
-            framework: net6.0
-            sdk: 6.0.x
-            runtime: -x64
-            codecov: false
+          # - os: ubuntu-latest
+          #   framework: net7.0
+          #   sdk: 7.0.x
+          #   sdk-preview: true
+          #   runtime: -x64
+          #   codecov: false
+          # - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
+          #   framework: net7.0
+          #   sdk: 7.0.x
+          #   sdk-preview: true
+          #   runtime: -x64
+          #   codecov: false
+          # - os: windows-latest
+          #   framework: net7.0
+          #   sdk: 7.0.x
+          #   sdk-preview: true
+          #   runtime: -x64
+          #   codecov: false
+          # - os: buildjet-4vcpu-ubuntu-2204-arm
+          #   framework: net7.0
+          #   sdk: 7.0.x
+          #   sdk-preview: true
+          #   runtime: -x64
+          #   codecov: false
+          # - os: ubuntu-latest
+          #   framework: net6.0
+          #   sdk: 6.0.x
+          #   runtime: -x64
+          #   codecov: false
+          # - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
+          #   framework: net6.0
+          #   sdk: 6.0.x
+          #   runtime: -x64
+          #   codecov: false
           - os: windows-latest
             framework: net6.0
             sdk: 6.0.x

From e046be656dd2010b254ba9fc4d5bdb6dd097bdfa Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 16:24:19 +1000
Subject: [PATCH 10/18] Now test ubuntu net6 again

---
 .github/workflows/build-and-test.yml | 14 +++++++-------
 ci-build.ps1                         |  3 +++
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index ccab6d574b..a0f9f1b8bc 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -43,21 +43,21 @@ jobs:
           #   sdk-preview: true
           #   runtime: -x64
           #   codecov: false
-          # - os: ubuntu-latest
+          - os: ubuntu-latest
+            framework: net6.0
+            sdk: 6.0.x
+            runtime: -x64
+            codecov: false
+          # - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
           #   framework: net6.0
           #   sdk: 6.0.x
           #   runtime: -x64
           #   codecov: false
-          # - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
+          # - os: windows-latest
           #   framework: net6.0
           #   sdk: 6.0.x
           #   runtime: -x64
           #   codecov: false
-          - os: windows-latest
-            framework: net6.0
-            sdk: 6.0.x
-            runtime: -x64
-            codecov: false
         exclude:
           - isARM: false
             options:
diff --git a/ci-build.ps1 b/ci-build.ps1
index a98a5e27f8..d465d8da79 100644
--- a/ci-build.ps1
+++ b/ci-build.ps1
@@ -3,11 +3,14 @@ param(
   [string]$targetFramework
 )
 
+Write-Output "PATH"
 Write-Output $env:PATH
 
+Write-Output "DOTNET_LIST"
 dotnet --list-sdks
 
 # Confirm dotnet version.
+Write-Output "DOTNET_VERSION"
 dotnet --version
 
 dotnet clean -c Release

From 3a286c53bb7e8bbde0cd90c943b3d7b84949b120 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 16:27:50 +1000
Subject: [PATCH 11/18] Try installing multiple sdks

---
 .github/workflows/build-and-test.yml | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index a0f9f1b8bc..b46429379d 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -112,6 +112,8 @@ jobs:
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
+            8.0.x
+            7.0.x
             6.0.x
 
       - name: DotNet Setup Preview
@@ -121,12 +123,12 @@ jobs:
           dotnet-version: |
             7.0.x
 
-      - name: Ensure DotNet Path
-        if: ${{ matrix.options.os != 'windows-latest' }}
-        run: echo "/usr/share/dotnet" >> $GITHUB_PATH
+      # - name: Ensure DotNet Path
+      #   if: ${{ matrix.options.os != 'windows-latest' }}
+      #   run: echo "/usr/share/dotnet" >> $GITHUB_PATH
 
-      - name: Confirm DotNet Version
-        run: dotnet --version
+      # - name: Confirm DotNet Version
+      #   run: dotnet --version
 
       - name: DotNet Build
         if: ${{ matrix.options.sdk-preview != true }}

From 49a11182efd96a1b911c9a94414c4c42277058b0 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 30 Jan 2025 16:36:28 +1000
Subject: [PATCH 12/18] Re-enable all builds

---
 .github/workflows/build-and-test.yml | 83 ++++++++++++----------------
 .github/workflows/code-coverage.yml  |  8 +--
 ci-build.ps1                         | 10 ----
 3 files changed, 36 insertions(+), 65 deletions(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index b46429379d..a35175ff49 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -19,45 +19,45 @@ jobs:
         isARM:
           - ${{ contains(github.event.pull_request.labels.*.name, 'arch:arm32') || contains(github.event.pull_request.labels.*.name, 'arch:arm64') }}
         options:
-          # - os: ubuntu-latest
-          #   framework: net7.0
-          #   sdk: 7.0.x
-          #   sdk-preview: true
-          #   runtime: -x64
-          #   codecov: false
-          # - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
-          #   framework: net7.0
-          #   sdk: 7.0.x
-          #   sdk-preview: true
-          #   runtime: -x64
-          #   codecov: false
-          # - os: windows-latest
-          #   framework: net7.0
-          #   sdk: 7.0.x
-          #   sdk-preview: true
-          #   runtime: -x64
-          #   codecov: false
-          # - os: buildjet-4vcpu-ubuntu-2204-arm
-          #   framework: net7.0
-          #   sdk: 7.0.x
-          #   sdk-preview: true
-          #   runtime: -x64
-          #   codecov: false
           - os: ubuntu-latest
+            framework: net7.0
+            sdk: 7.0.x
+            sdk-preview: true
+            runtime: -x64
+            codecov: false
+          - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
+            framework: net7.0
+            sdk: 7.0.x
+            sdk-preview: true
+            runtime: -x64
+            codecov: false
+          - os: windows-latest
+            framework: net7.0
+            sdk: 7.0.x
+            sdk-preview: true
+            runtime: -x64
+            codecov: false
+          - os: buildjet-4vcpu-ubuntu-2204-arm
+            framework: net7.0
+            sdk: 7.0.x
+            sdk-preview: true
+            runtime: -x64
+            codecov: false
+          - os: ubuntu-latest
+            framework: net6.0
+            sdk: 6.0.x
+            runtime: -x64
+            codecov: false
+          - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
+            framework: net6.0
+            sdk: 6.0.x
+            runtime: -x64
+            codecov: false
+          - os: windows-latest
             framework: net6.0
             sdk: 6.0.x
             runtime: -x64
             codecov: false
-          # - os: macos-13 # macos-latest runs on arm64 runners where libgdiplus is unavailable
-          #   framework: net6.0
-          #   sdk: 6.0.x
-          #   runtime: -x64
-          #   codecov: false
-          # - os: windows-latest
-          #   framework: net6.0
-          #   sdk: 6.0.x
-          #   runtime: -x64
-          #   codecov: false
         exclude:
           - isARM: false
             options:
@@ -108,7 +108,6 @@ jobs:
           restore-keys: ${{ runner.os }}-nuget-
 
       - name: DotNet Setup
-        if: ${{ matrix.options.sdk-preview != true }}
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
@@ -116,20 +115,6 @@ jobs:
             7.0.x
             6.0.x
 
-      - name: DotNet Setup Preview
-        if: ${{ matrix.options.sdk-preview == true }}
-        uses: actions/setup-dotnet@v4
-        with:
-          dotnet-version: |
-            7.0.x
-
-      # - name: Ensure DotNet Path
-      #   if: ${{ matrix.options.os != 'windows-latest' }}
-      #   run: echo "/usr/share/dotnet" >> $GITHUB_PATH
-
-      # - name: Confirm DotNet Version
-      #   run: dotnet --version
-
       - name: DotNet Build
         if: ${{ matrix.options.sdk-preview != true }}
         shell: pwsh
diff --git a/.github/workflows/code-coverage.yml b/.github/workflows/code-coverage.yml
index da7d792cd8..db9aca0b08 100644
--- a/.github/workflows/code-coverage.yml
+++ b/.github/workflows/code-coverage.yml
@@ -61,14 +61,10 @@ jobs:
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
+            8.0.x
+            7.0.x
             6.0.x
 
-      - name: Ensure DotNet Path
-        run: echo "/usr/share/dotnet" >> $GITHUB_PATH
-
-      - name: Confirm DotNet Version
-        run: dotnet --version  # This will now find dotnet in /usr/share/dotnet
-
       - name: DotNet Build
         shell: pwsh
         run: ./ci-build.ps1 "${{matrix.options.framework}}"
diff --git a/ci-build.ps1 b/ci-build.ps1
index d465d8da79..d45af6ff4d 100644
--- a/ci-build.ps1
+++ b/ci-build.ps1
@@ -3,16 +3,6 @@ param(
   [string]$targetFramework
 )
 
-Write-Output "PATH"
-Write-Output $env:PATH
-
-Write-Output "DOTNET_LIST"
-dotnet --list-sdks
-
-# Confirm dotnet version.
-Write-Output "DOTNET_VERSION"
-dotnet --version
-
 dotnet clean -c Release
 
 $repositoryUrl = "https://github.com/$env:GITHUB_REPOSITORY"

From b99bf32bb19a1e88083cae48a8c96a7531859604 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Tue, 4 Feb 2025 18:41:10 +1000
Subject: [PATCH 13/18] Gracefully handle LZW overflows

---
 src/ImageSharp/Formats/Gif/LzwDecoder.cs             |  6 ++++--
 .../ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs  | 12 ++++++++++++
 tests/ImageSharp.Tests/TestImages.cs                 |  2 ++
 tests/Images/Input/Gif/issues/issue_2859_A.gif       |  3 +++
 tests/Images/Input/Gif/issues/issue_2859_B.gif       |  3 +++
 5 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 tests/Images/Input/Gif/issues/issue_2859_A.gif
 create mode 100644 tests/Images/Input/Gif/issues/issue_2859_B.gif

diff --git a/src/ImageSharp/Formats/Gif/LzwDecoder.cs b/src/ImageSharp/Formats/Gif/LzwDecoder.cs
index ec33f2b3ed..7a082e3674 100644
--- a/src/ImageSharp/Formats/Gif/LzwDecoder.cs
+++ b/src/ImageSharp/Formats/Gif/LzwDecoder.cs
@@ -137,6 +137,7 @@ public void DecodePixelRow(Span<byte> indices)
         ref int suffixRef = ref MemoryMarshal.GetReference(this.suffix.GetSpan());
         ref int pixelStackRef = ref MemoryMarshal.GetReference(this.pixelStack.GetSpan());
         Span<byte> buffer = this.scratchBuffer.GetSpan();
+        int maxTop = this.pixelStack.Length() - 1;
 
         int x = 0;
         int xyz = 0;
@@ -204,7 +205,7 @@ public void DecodePixelRow(Span<byte> indices)
                     this.code = this.oldCode;
                 }
 
-                while (this.code > this.clearCode)
+                while (this.code > this.clearCode && this.top < maxTop)
                 {
                     Unsafe.Add(ref pixelStackRef, (uint)this.top++) = Unsafe.Add(ref suffixRef, (uint)this.code);
                     this.code = Unsafe.Add(ref prefixRef, (uint)this.code);
@@ -250,6 +251,7 @@ public void SkipIndices(int length)
         ref int suffixRef = ref MemoryMarshal.GetReference(this.suffix.GetSpan());
         ref int pixelStackRef = ref MemoryMarshal.GetReference(this.pixelStack.GetSpan());
         Span<byte> buffer = this.scratchBuffer.GetSpan();
+        int maxTop = this.pixelStack.Length() - 1;
 
         int xyz = 0;
         while (xyz < length)
@@ -316,7 +318,7 @@ public void SkipIndices(int length)
                     this.code = this.oldCode;
                 }
 
-                while (this.code > this.clearCode)
+                while (this.code > this.clearCode && this.top < maxTop)
                 {
                     Unsafe.Add(ref pixelStackRef, (uint)this.top++) = Unsafe.Add(ref suffixRef, (uint)this.code);
                     this.code = Unsafe.Add(ref prefixRef, (uint)this.code);
diff --git a/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs
index f4e6487a57..bc6eeedcbe 100644
--- a/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs
@@ -334,4 +334,16 @@ public void IssueTooLargeLzwBits<TPixel>(TestImageProvider<TPixel> provider)
         image.DebugSaveMultiFrame(provider);
         image.CompareToReferenceOutputMultiFrame(provider, ImageComparer.Exact);
     }
+
+    // https://github.com/SixLabors/ImageSharp/issues/2859
+    [Theory]
+    [WithFile(TestImages.Gif.Issues.Issue2859_A, PixelTypes.Rgba32)]
+    [WithFile(TestImages.Gif.Issues.Issue2859_B, PixelTypes.Rgba32)]
+    public void Issue2859_LZWPixelStackOverflow<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        using Image<TPixel> image = provider.GetImage();
+        image.DebugSaveMultiFrame(provider);
+        image.CompareToReferenceOutputMultiFrame(provider, ImageComparer.Exact);
+    }
 }
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index a0e951e70d..fa3f38799a 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -535,6 +535,8 @@ public static class Issues
             public const string Issue2450_B = "Gif/issues/issue_2450_2.gif";
             public const string Issue2198 = "Gif/issues/issue_2198.gif";
             public const string Issue2758 = "Gif/issues/issue_2758.gif";
+            public const string Issue2859_A = "Gif/issues/issue_2859_A.gif";
+            public const string Issue2859_B = "Gif/issues/issue_2859_B.gif";
         }
 
         public static readonly string[] Animated =
diff --git a/tests/Images/Input/Gif/issues/issue_2859_A.gif b/tests/Images/Input/Gif/issues/issue_2859_A.gif
new file mode 100644
index 0000000000..f19a047525
--- /dev/null
+++ b/tests/Images/Input/Gif/issues/issue_2859_A.gif
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:50a1a4afc62a3a36ff83596f1eb55d91cdd184c64e0d1339bbea17205c23eee1
+size 3406142
diff --git a/tests/Images/Input/Gif/issues/issue_2859_B.gif b/tests/Images/Input/Gif/issues/issue_2859_B.gif
new file mode 100644
index 0000000000..109b0f8797
--- /dev/null
+++ b/tests/Images/Input/Gif/issues/issue_2859_B.gif
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:db9b2992be772a4f0ac495e994a17c7c50fb6de9794cfb9afc4a3dc26ffdfae0
+size 4543

From 170979743ece9b10414868865897378be8eb7ba8 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Tue, 4 Feb 2025 18:44:25 +1000
Subject: [PATCH 14/18] Add reference output

---
 .../00.png                                                     | 3 +++
 .../00.png                                                     | 3 +++
 .../01.png                                                     | 3 +++
 3 files changed, 9 insertions(+)
 create mode 100644 tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_A.gif/00.png
 create mode 100644 tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/00.png
 create mode 100644 tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/01.png

diff --git a/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_A.gif/00.png b/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_A.gif/00.png
new file mode 100644
index 0000000000..d8c8df1263
--- /dev/null
+++ b/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_A.gif/00.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:daa78347749c6ff49891e2e379a373599cd35c98b453af9bf8eac52f615f935c
+size 12237
diff --git a/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/00.png b/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/00.png
new file mode 100644
index 0000000000..36c3683187
--- /dev/null
+++ b/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/00.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:731299281f942f277ce6803e0adda3b5dd0395eb79cae26cabc9d56905fae0fd
+size 1833
diff --git a/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/01.png b/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/01.png
new file mode 100644
index 0000000000..c03e5817f0
--- /dev/null
+++ b/tests/Images/External/ReferenceOutput/GifDecoderTests/Issue2859_LZWPixelStackOverflow_Rgba32_issue_2859_B.gif/01.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:50ccac7739142578d99a76b6d39ba377099d4a7ac30cbb0a5aee44ef1e7c9c8c
+size 1271

From 9cb022bc96882c0484d6f617babb5141e4d224f0 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Tue, 4 Feb 2025 18:52:00 +1000
Subject: [PATCH 15/18] Update build-and-test.yml

---
 .github/workflows/build-and-test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index a35175ff49..d9e0f1e08f 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -146,7 +146,7 @@ jobs:
           XUNIT_PATH: .\tests\ImageSharp.Tests # Required for xunit
 
       - name: Export Failed Output
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: failure()
         with:
           name: actual_output_${{ runner.os }}_${{ matrix.options.framework }}${{ matrix.options.runtime }}.zip

From ca077545c45263f17e5f7764a155cf20e44f5580 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Wed, 5 Feb 2025 15:15:01 +1000
Subject: [PATCH 16/18] Use safe code.

---
 src/ImageSharp/Formats/Gif/LzwDecoder.cs | 308 ++++++++++++++---------
 1 file changed, 183 insertions(+), 125 deletions(-)

diff --git a/src/ImageSharp/Formats/Gif/LzwDecoder.cs b/src/ImageSharp/Formats/Gif/LzwDecoder.cs
index 7a082e3674..ece0f22888 100644
--- a/src/ImageSharp/Formats/Gif/LzwDecoder.cs
+++ b/src/ImageSharp/Formats/Gif/LzwDecoder.cs
@@ -3,7 +3,6 @@
 
 using System.Buffers;
 using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.Memory;
 
@@ -37,22 +36,22 @@ internal sealed class LzwDecoder : IDisposable
     /// <summary>
     /// The prefix buffer.
     /// </summary>
-    private readonly IMemoryOwner<int> prefix;
+    private readonly IMemoryOwner<int> prefixOwner;
 
     /// <summary>
     /// The suffix buffer.
     /// </summary>
-    private readonly IMemoryOwner<int> suffix;
+    private readonly IMemoryOwner<int> suffixOwner;
 
     /// <summary>
     /// The scratch buffer for reading data blocks.
     /// </summary>
-    private readonly IMemoryOwner<byte> scratchBuffer;
+    private readonly IMemoryOwner<byte> bufferOwner;
 
     /// <summary>
     /// The pixel stack buffer.
     /// </summary>
-    private readonly IMemoryOwner<int> pixelStack;
+    private readonly IMemoryOwner<int> pixelStackOwner;
     private readonly int minCodeSize;
     private readonly int clearCode;
     private readonly int endCode;
@@ -80,10 +79,10 @@ public LzwDecoder(MemoryAllocator memoryAllocator, BufferedReadStream stream, in
     {
         this.stream = stream ?? throw new ArgumentNullException(nameof(stream));
 
-        this.prefix = memoryAllocator.Allocate<int>(MaxStackSize, AllocationOptions.Clean);
-        this.suffix = memoryAllocator.Allocate<int>(MaxStackSize, AllocationOptions.Clean);
-        this.pixelStack = memoryAllocator.Allocate<int>(MaxStackSize + 1, AllocationOptions.Clean);
-        this.scratchBuffer = memoryAllocator.Allocate<byte>(byte.MaxValue, AllocationOptions.None);
+        this.prefixOwner = memoryAllocator.Allocate<int>(MaxStackSize, AllocationOptions.Clean);
+        this.suffixOwner = memoryAllocator.Allocate<int>(MaxStackSize, AllocationOptions.Clean);
+        this.pixelStackOwner = memoryAllocator.Allocate<int>(MaxStackSize + 1, AllocationOptions.Clean);
+        this.bufferOwner = memoryAllocator.Allocate<byte>(byte.MaxValue, AllocationOptions.None);
         this.minCodeSize = minCodeSize;
 
         // Calculate the clear code. The value of the clear code is 2 ^ minCodeSize
@@ -93,10 +92,11 @@ public LzwDecoder(MemoryAllocator memoryAllocator, BufferedReadStream stream, in
         this.endCode = this.clearCode + 1;
         this.availableCode = this.clearCode + 2;
 
-        ref int suffixRef = ref MemoryMarshal.GetReference(this.suffix.GetSpan());
-        for (this.code = 0; this.code < this.clearCode; this.code++)
+        Span<int> suffix = this.suffixOwner.GetSpan();
+        int max = Math.Min(this.clearCode, suffix.Length);
+        for (this.code = 0; this.code < max; this.code++)
         {
-            Unsafe.Add(ref suffixRef, (uint)this.code) = (byte)this.code;
+            suffix[this.code] = (byte)this.code;
         }
     }
 
@@ -132,113 +132,140 @@ public void DecodePixelRow(Span<byte> indices)
     {
         indices.Clear();
 
-        ref byte pixelsRowRef = ref MemoryMarshal.GetReference(indices);
-        ref int prefixRef = ref MemoryMarshal.GetReference(this.prefix.GetSpan());
-        ref int suffixRef = ref MemoryMarshal.GetReference(this.suffix.GetSpan());
-        ref int pixelStackRef = ref MemoryMarshal.GetReference(this.pixelStack.GetSpan());
-        Span<byte> buffer = this.scratchBuffer.GetSpan();
-        int maxTop = this.pixelStack.Length() - 1;
+        // Get span values from the owners.
+        Span<int> prefix = this.prefixOwner.GetSpan();
+        Span<int> suffix = this.suffixOwner.GetSpan();
+        Span<int> pixelStack = this.pixelStackOwner.GetSpan();
+        Span<byte> buffer = this.bufferOwner.GetSpan();
+        int maxTop = this.pixelStackOwner.Length() - 1;
+
+        // Cache frequently accessed instance fields into locals.
+        // This helps avoid repeated field loads inside the tight loop.
+        BufferedReadStream stream = this.stream;
+        int top = this.top;
+        int bits = this.bits;
+        int codeSize = this.codeSize;
+        int codeMask = this.codeMask;
+        int minCodeSize = this.minCodeSize;
+        int availableCode = this.availableCode;
+        int oldCode = this.oldCode;
+        int first = this.first;
+        int data = this.data;
+        int count = this.count;
+        int bufferIndex = this.bufferIndex;
+        int code = this.code;
+        int clearCode = this.clearCode;
+        int endCode = this.endCode;
 
-        int x = 0;
         int xyz = 0;
         while (xyz < indices.Length)
         {
-            if (this.top == 0)
+            if (top == 0)
             {
-                if (this.bits < this.codeSize)
+                if (bits < codeSize)
                 {
                     // Load bytes until there are enough bits for a code.
-                    if (this.count == 0)
+                    if (count == 0)
                     {
                         // Read a new data block.
-                        this.count = this.ReadBlock(buffer);
-                        if (this.count == 0)
+                        count = ReadBlock(stream, buffer);
+                        if (count == 0)
                         {
                             break;
                         }
 
-                        this.bufferIndex = 0;
+                        bufferIndex = 0;
                     }
 
-                    this.data += buffer[this.bufferIndex] << this.bits;
-
-                    this.bits += 8;
-                    this.bufferIndex++;
-                    this.count--;
+                    data += buffer[bufferIndex] << bits;
+                    bits += 8;
+                    bufferIndex++;
+                    count--;
                     continue;
                 }
 
                 // Get the next code
-                this.code = this.data & this.codeMask;
-                this.data >>= this.codeSize;
-                this.bits -= this.codeSize;
+                code = data & codeMask;
+                data >>= codeSize;
+                bits -= codeSize;
 
                 // Interpret the code
-                if (this.code > this.availableCode || this.code == this.endCode)
+                if (code > availableCode || code == endCode)
                 {
                     break;
                 }
 
-                if (this.code == this.clearCode)
+                if (code == clearCode)
                 {
                     // Reset the decoder
-                    this.codeSize = this.minCodeSize + 1;
-                    this.codeMask = (1 << this.codeSize) - 1;
-                    this.availableCode = this.clearCode + 2;
-                    this.oldCode = NullCode;
+                    codeSize = minCodeSize + 1;
+                    codeMask = (1 << codeSize) - 1;
+                    availableCode = clearCode + 2;
+                    oldCode = NullCode;
                     continue;
                 }
 
-                if (this.oldCode == NullCode)
+                if (oldCode == NullCode)
                 {
-                    Unsafe.Add(ref pixelStackRef, (uint)this.top++) = Unsafe.Add(ref suffixRef, (uint)this.code);
-                    this.oldCode = this.code;
-                    this.first = this.code;
+                    pixelStack[top++] = suffix[code];
+                    oldCode = code;
+                    first = code;
                     continue;
                 }
 
-                int inCode = this.code;
-                if (this.code == this.availableCode)
+                int inCode = code;
+                if (code == availableCode)
                 {
-                    Unsafe.Add(ref pixelStackRef, (uint)this.top++) = (byte)this.first;
-
-                    this.code = this.oldCode;
+                    pixelStack[top++] = first;
+                    code = oldCode;
                 }
 
-                while (this.code > this.clearCode && this.top < maxTop)
+                while (code > clearCode && top < maxTop)
                 {
-                    Unsafe.Add(ref pixelStackRef, (uint)this.top++) = Unsafe.Add(ref suffixRef, (uint)this.code);
-                    this.code = Unsafe.Add(ref prefixRef, (uint)this.code);
+                    pixelStack[top++] = suffix[code];
+                    code = prefix[code];
                 }
 
-                int suffixCode = Unsafe.Add(ref suffixRef, (uint)this.code);
-                this.first = suffixCode;
-                Unsafe.Add(ref pixelStackRef, (uint)this.top++) = suffixCode;
+                int suffixCode = suffix[code];
+                first = suffixCode;
+                pixelStack[top++] = suffixCode;
 
-                // Fix for Gifs that have "deferred clear code" as per here :
+                // Fix for GIFs that have "deferred clear code" as per:
                 // https://bugzilla.mozilla.org/show_bug.cgi?id=55918
-                if (this.availableCode < MaxStackSize)
+                if (availableCode < MaxStackSize)
                 {
-                    Unsafe.Add(ref prefixRef, (uint)this.availableCode) = this.oldCode;
-                    Unsafe.Add(ref suffixRef, (uint)this.availableCode) = this.first;
-                    this.availableCode++;
-                    if (this.availableCode == this.codeMask + 1 && this.availableCode < MaxStackSize)
+                    prefix[availableCode] = oldCode;
+                    suffix[availableCode] = first;
+                    availableCode++;
+                    if (availableCode == codeMask + 1 && availableCode < MaxStackSize)
                     {
-                        this.codeSize++;
-                        this.codeMask = (1 << this.codeSize) - 1;
+                        codeSize++;
+                        codeMask = (1 << codeSize) - 1;
                     }
                 }
 
-                this.oldCode = inCode;
+                oldCode = inCode;
             }
 
             // Pop a pixel off the pixel stack.
-            this.top--;
+            top--;
 
-            // Clear missing pixels
-            xyz++;
-            Unsafe.Add(ref pixelsRowRef, (uint)x++) = (byte)Unsafe.Add(ref pixelStackRef, (uint)this.top);
+            // Clear missing pixels.
+            indices[xyz++] = (byte)pixelStack[top];
         }
+
+        // Write back the local values to the instance fields.
+        this.top = top;
+        this.bits = bits;
+        this.codeSize = codeSize;
+        this.codeMask = codeMask;
+        this.availableCode = availableCode;
+        this.oldCode = oldCode;
+        this.first = first;
+        this.data = data;
+        this.count = count;
+        this.bufferIndex = bufferIndex;
+        this.code = code;
     }
 
     /// <summary>
@@ -247,131 +274,162 @@ public void DecodePixelRow(Span<byte> indices)
     /// <param name="length">The resulting index table length.</param>
     public void SkipIndices(int length)
     {
-        ref int prefixRef = ref MemoryMarshal.GetReference(this.prefix.GetSpan());
-        ref int suffixRef = ref MemoryMarshal.GetReference(this.suffix.GetSpan());
-        ref int pixelStackRef = ref MemoryMarshal.GetReference(this.pixelStack.GetSpan());
-        Span<byte> buffer = this.scratchBuffer.GetSpan();
-        int maxTop = this.pixelStack.Length() - 1;
+        // Get span values from the owners.
+        Span<int> prefix = this.prefixOwner.GetSpan();
+        Span<int> suffix = this.suffixOwner.GetSpan();
+        Span<int> pixelStack = this.pixelStackOwner.GetSpan();
+        Span<byte> buffer = this.bufferOwner.GetSpan();
+        int maxTop = this.pixelStackOwner.Length() - 1;
+
+        // Cache frequently accessed instance fields into locals.
+        // This helps avoid repeated field loads inside the tight loop.
+        BufferedReadStream stream = this.stream;
+        int top = this.top;
+        int bits = this.bits;
+        int codeSize = this.codeSize;
+        int codeMask = this.codeMask;
+        int minCodeSize = this.minCodeSize;
+        int availableCode = this.availableCode;
+        int oldCode = this.oldCode;
+        int first = this.first;
+        int data = this.data;
+        int count = this.count;
+        int bufferIndex = this.bufferIndex;
+        int code = this.code;
+        int clearCode = this.clearCode;
+        int endCode = this.endCode;
 
         int xyz = 0;
         while (xyz < length)
         {
-            if (this.top == 0)
+            if (top == 0)
             {
-                if (this.bits < this.codeSize)
+                if (bits < codeSize)
                 {
                     // Load bytes until there are enough bits for a code.
-                    if (this.count == 0)
+                    if (count == 0)
                     {
                         // Read a new data block.
-                        this.count = this.ReadBlock(buffer);
-                        if (this.count == 0)
+                        count = ReadBlock(stream, buffer);
+                        if (count == 0)
                         {
                             break;
                         }
 
-                        this.bufferIndex = 0;
+                        bufferIndex = 0;
                     }
 
-                    this.data += buffer[this.bufferIndex] << this.bits;
-
-                    this.bits += 8;
-                    this.bufferIndex++;
-                    this.count--;
+                    data += buffer[bufferIndex] << bits;
+                    bits += 8;
+                    bufferIndex++;
+                    count--;
                     continue;
                 }
 
                 // Get the next code
-                this.code = this.data & this.codeMask;
-                this.data >>= this.codeSize;
-                this.bits -= this.codeSize;
+                code = data & codeMask;
+                data >>= codeSize;
+                bits -= codeSize;
 
                 // Interpret the code
-                if (this.code > this.availableCode || this.code == this.endCode)
+                if (code > availableCode || code == endCode)
                 {
                     break;
                 }
 
-                if (this.code == this.clearCode)
+                if (code == clearCode)
                 {
                     // Reset the decoder
-                    this.codeSize = this.minCodeSize + 1;
-                    this.codeMask = (1 << this.codeSize) - 1;
-                    this.availableCode = this.clearCode + 2;
-                    this.oldCode = NullCode;
+                    codeSize = minCodeSize + 1;
+                    codeMask = (1 << codeSize) - 1;
+                    availableCode = clearCode + 2;
+                    oldCode = NullCode;
                     continue;
                 }
 
-                if (this.oldCode == NullCode)
+                if (oldCode == NullCode)
                 {
-                    Unsafe.Add(ref pixelStackRef, (uint)this.top++) = Unsafe.Add(ref suffixRef, (uint)this.code);
-                    this.oldCode = this.code;
-                    this.first = this.code;
+                    pixelStack[top++] = suffix[code];
+                    oldCode = code;
+                    first = code;
                     continue;
                 }
 
-                int inCode = this.code;
-                if (this.code == this.availableCode)
+                int inCode = code;
+                if (code == availableCode)
                 {
-                    Unsafe.Add(ref pixelStackRef, (uint)this.top++) = (byte)this.first;
-
-                    this.code = this.oldCode;
+                    pixelStack[top++] = first;
+                    code = oldCode;
                 }
 
-                while (this.code > this.clearCode && this.top < maxTop)
+                while (code > clearCode && top < maxTop)
                 {
-                    Unsafe.Add(ref pixelStackRef, (uint)this.top++) = Unsafe.Add(ref suffixRef, (uint)this.code);
-                    this.code = Unsafe.Add(ref prefixRef, (uint)this.code);
+                    pixelStack[top++] = suffix[code];
+                    code = prefix[code];
                 }
 
-                int suffixCode = Unsafe.Add(ref suffixRef, (uint)this.code);
-                this.first = suffixCode;
-                Unsafe.Add(ref pixelStackRef, (uint)this.top++) = suffixCode;
+                int suffixCode = suffix[code];
+                first = suffixCode;
+                pixelStack[top++] = suffixCode;
 
-                // Fix for Gifs that have "deferred clear code" as per here :
+                // Fix for GIFs that have "deferred clear code" as per:
                 // https://bugzilla.mozilla.org/show_bug.cgi?id=55918
-                if (this.availableCode < MaxStackSize)
+                if (availableCode < MaxStackSize)
                 {
-                    Unsafe.Add(ref prefixRef, (uint)this.availableCode) = this.oldCode;
-                    Unsafe.Add(ref suffixRef, (uint)this.availableCode) = this.first;
-                    this.availableCode++;
-                    if (this.availableCode == this.codeMask + 1 && this.availableCode < MaxStackSize)
+                    prefix[availableCode] = oldCode;
+                    suffix[availableCode] = first;
+                    availableCode++;
+                    if (availableCode == codeMask + 1 && availableCode < MaxStackSize)
                     {
-                        this.codeSize++;
-                        this.codeMask = (1 << this.codeSize) - 1;
+                        codeSize++;
+                        codeMask = (1 << codeSize) - 1;
                     }
                 }
 
-                this.oldCode = inCode;
+                oldCode = inCode;
             }
 
             // Pop a pixel off the pixel stack.
-            this.top--;
+            top--;
 
-            // Clear missing pixels
+            // Skip missing pixels.
             xyz++;
         }
+
+        // Write back the local values to the instance fields.
+        this.top = top;
+        this.bits = bits;
+        this.codeSize = codeSize;
+        this.codeMask = codeMask;
+        this.availableCode = availableCode;
+        this.oldCode = oldCode;
+        this.first = first;
+        this.data = data;
+        this.count = count;
+        this.bufferIndex = bufferIndex;
+        this.code = code;
     }
 
     /// <summary>
     /// Reads the next data block from the stream. A data block begins with a byte,
     /// which defines the size of the block, followed by the block itself.
     /// </summary>
+    /// <param name="stream">The stream to read from.</param>
     /// <param name="buffer">The buffer to store the block in.</param>
     /// <returns>
     /// The <see cref="int"/>.
     /// </returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private int ReadBlock(Span<byte> buffer)
+    private static int ReadBlock(BufferedReadStream stream, Span<byte> buffer)
     {
-        int bufferSize = this.stream.ReadByte();
+        int bufferSize = stream.ReadByte();
 
         if (bufferSize < 1)
         {
             return 0;
         }
 
-        int count = this.stream.Read(buffer, 0, bufferSize);
+        int count = stream.Read(buffer, 0, bufferSize);
 
         return count != bufferSize ? 0 : bufferSize;
     }
@@ -379,9 +437,9 @@ private int ReadBlock(Span<byte> buffer)
     /// <inheritdoc />
     public void Dispose()
     {
-        this.prefix.Dispose();
-        this.suffix.Dispose();
-        this.pixelStack.Dispose();
-        this.scratchBuffer.Dispose();
+        this.prefixOwner.Dispose();
+        this.suffixOwner.Dispose();
+        this.pixelStackOwner.Dispose();
+        this.bufferOwner.Dispose();
     }
 }

From 20e5596f2a450c7911053cf3ba3fb7d5f03f7f62 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Mon, 10 Feb 2025 11:45:47 +1000
Subject: [PATCH 17/18] Clean up and optimize

---
 src/ImageSharp/Formats/Gif/LzwDecoder.cs | 33 ++++++++++++------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/ImageSharp/Formats/Gif/LzwDecoder.cs b/src/ImageSharp/Formats/Gif/LzwDecoder.cs
index ece0f22888..b33d1f3d48 100644
--- a/src/ImageSharp/Formats/Gif/LzwDecoder.cs
+++ b/src/ImageSharp/Formats/Gif/LzwDecoder.cs
@@ -78,6 +78,7 @@ internal sealed class LzwDecoder : IDisposable
     public LzwDecoder(MemoryAllocator memoryAllocator, BufferedReadStream stream, int minCodeSize)
     {
         this.stream = stream ?? throw new ArgumentNullException(nameof(stream));
+        Guard.IsTrue(IsValidMinCodeSize(minCodeSize), nameof(minCodeSize), "Invalid minimum code size.");
 
         this.prefixOwner = memoryAllocator.Allocate<int>(MaxStackSize, AllocationOptions.Clean);
         this.suffixOwner = memoryAllocator.Allocate<int>(MaxStackSize, AllocationOptions.Clean);
@@ -92,12 +93,15 @@ public LzwDecoder(MemoryAllocator memoryAllocator, BufferedReadStream stream, in
         this.endCode = this.clearCode + 1;
         this.availableCode = this.clearCode + 2;
 
-        Span<int> suffix = this.suffixOwner.GetSpan();
-        int max = Math.Min(this.clearCode, suffix.Length);
-        for (this.code = 0; this.code < max; this.code++)
+        // Fill the suffix buffer with the initial values represented by the number of colors.
+        Span<int> suffix = this.suffixOwner.GetSpan()[..this.clearCode];
+        int i;
+        for (i = 0; i < suffix.Length; i++)
         {
-            suffix[this.code] = (byte)this.code;
+            suffix[i] = i;
         }
+
+        this.code = i;
     }
 
     /// <summary>
@@ -112,8 +116,7 @@ public static bool IsValidMinCodeSize(int minCodeSize)
         // It is possible to specify a larger LZW minimum code size than the palette length in bits
         // which may leave a gap in the codes where no colors are assigned.
         // http://www.matthewflickinger.com/lab/whatsinagif/lzw_image_data.asp#lzw_compression
-        int clearCode = 1 << minCodeSize;
-        if (minCodeSize < 2 || minCodeSize > MaximumLzwBits || clearCode > MaxStackSize)
+        if (minCodeSize < 2 || minCodeSize > MaximumLzwBits || 1 << minCodeSize > MaxStackSize)
         {
             // Don't attempt to decode the frame indices.
             // Theoretically we could determine a min code size from the length of the provided
@@ -137,7 +140,6 @@ public void DecodePixelRow(Span<byte> indices)
         Span<int> suffix = this.suffixOwner.GetSpan();
         Span<int> pixelStack = this.pixelStackOwner.GetSpan();
         Span<byte> buffer = this.bufferOwner.GetSpan();
-        int maxTop = this.pixelStackOwner.Length() - 1;
 
         // Cache frequently accessed instance fields into locals.
         // This helps avoid repeated field loads inside the tight loop.
@@ -157,8 +159,8 @@ public void DecodePixelRow(Span<byte> indices)
         int clearCode = this.clearCode;
         int endCode = this.endCode;
 
-        int xyz = 0;
-        while (xyz < indices.Length)
+        int i = 0;
+        while (i < indices.Length)
         {
             if (top == 0)
             {
@@ -220,7 +222,7 @@ public void DecodePixelRow(Span<byte> indices)
                     code = oldCode;
                 }
 
-                while (code > clearCode && top < maxTop)
+                while (code > clearCode && top < MaxStackSize)
                 {
                     pixelStack[top++] = suffix[code];
                     code = prefix[code];
@@ -251,7 +253,7 @@ public void DecodePixelRow(Span<byte> indices)
             top--;
 
             // Clear missing pixels.
-            indices[xyz++] = (byte)pixelStack[top];
+            indices[i++] = (byte)pixelStack[top];
         }
 
         // Write back the local values to the instance fields.
@@ -279,7 +281,6 @@ public void SkipIndices(int length)
         Span<int> suffix = this.suffixOwner.GetSpan();
         Span<int> pixelStack = this.pixelStackOwner.GetSpan();
         Span<byte> buffer = this.bufferOwner.GetSpan();
-        int maxTop = this.pixelStackOwner.Length() - 1;
 
         // Cache frequently accessed instance fields into locals.
         // This helps avoid repeated field loads inside the tight loop.
@@ -299,8 +300,8 @@ public void SkipIndices(int length)
         int clearCode = this.clearCode;
         int endCode = this.endCode;
 
-        int xyz = 0;
-        while (xyz < length)
+        int i = 0;
+        while (i < length)
         {
             if (top == 0)
             {
@@ -362,7 +363,7 @@ public void SkipIndices(int length)
                     code = oldCode;
                 }
 
-                while (code > clearCode && top < maxTop)
+                while (code > clearCode && top < MaxStackSize)
                 {
                     pixelStack[top++] = suffix[code];
                     code = prefix[code];
@@ -393,7 +394,7 @@ public void SkipIndices(int length)
             top--;
 
             // Skip missing pixels.
-            xyz++;
+            i++;
         }
 
         // Write back the local values to the instance fields.

From d04ec7b76635ee94521a232421ce96f4abab3969 Mon Sep 17 00:00:00 2001
From: antonfirsov <antonfir@gmail.com>
Date: Mon, 3 Mar 2025 17:38:59 +0100
Subject: [PATCH 18/18] workaround build issues

---
 src/ImageSharp/ImageSharp.csproj | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/ImageSharp/ImageSharp.csproj b/src/ImageSharp/ImageSharp.csproj
index b08c27c41b..be29b40a0e 100644
--- a/src/ImageSharp/ImageSharp.csproj
+++ b/src/ImageSharp/ImageSharp.csproj
@@ -13,6 +13,7 @@
     <PackageTags>Image Resize Crop Gif Jpg Jpeg Bitmap Pbm Png Tga Tiff WebP NetCore</PackageTags>
     <Description>A new, fully featured, fully managed, cross-platform, 2D graphics API for .NET</Description>
     <Configurations>Debug;Release</Configurations>
+    <LangVersion>preview</LangVersion>
   </PropertyGroup>
 
   <!--  This enables the nullable analysis and treats all nullable warnings as error-->