Remove stackalloc

src/ImageSharp/Formats/Gif/GifEncoderCore.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Buffers;
 using System.IO;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -217,10 +218,11 @@ namespace SixLabors.ImageSharp.Formats.Gif
             where TPixel : unmanaged, IPixel<TPixel>
         {
             // Transparent pixels are much more likely to be found at the end of a palette.
-            // Palette length maxes out at 256 so safe to stackalloc.
             int index = -1;
             ReadOnlySpan<TPixel> paletteSpan = quantized.Palette.Span;
-            Span<Rgba32> rgbaSpan = stackalloc Rgba32[paletteSpan.Length];
+
+            using IMemoryOwner<Rgba32> rgbaOwner = quantized.Configuration.MemoryAllocator.Allocate<Rgba32>(paletteSpan.Length);
+            Span<Rgba32> rgbaSpan = rgbaOwner.GetSpan();
             PixelOperations<TPixel>.Instance.ToRgba32(quantized.Configuration, paletteSpan, rgbaSpan);
             ref Rgba32 rgbaSpanRef = ref MemoryMarshal.GetReference(rgbaSpan);
 

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -566,8 +566,8 @@ namespace SixLabors.ImageSharp.Formats.Png
             ref byte alphaTableRef = ref MemoryMarshal.GetReference(alphaTable.GetSpan());
 
             // Bulk convert our palette to RGBA to allow assignment to tables.
-            // Palette length maxes out at 256 so safe to stackalloc.
-            Span<Rgba32> rgbaPaletteSpan = stackalloc Rgba32[paletteLength];
+            using IMemoryOwner<Rgba32> rgbaOwner = quantized.Configuration.MemoryAllocator.Allocate<Rgba32>(paletteLength);
+            Span<Rgba32> rgbaPaletteSpan = rgbaOwner.GetSpan();
             PixelOperations<TPixel>.Instance.ToRgba32(quantized.Configuration, quantized.Palette.Span, rgbaPaletteSpan);
             ref Rgba32 rgbaPaletteRef = ref MemoryMarshal.GetReference(rgbaPaletteSpan);
 

src/ImageSharp/Processing/Processors/Quantization/WuFrameQuantizer{TPixel}.cs

@@ -632,7 +632,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
         /// </summary>
         private void BuildCube()
         {
-            Span<double> vv = stackalloc double[this.maxColors];
+            // Store the volume variance.
+            using IMemoryOwner<double> vvOwner = this.Configuration.MemoryAllocator.Allocate<double>(this.maxColors);
+            Span<double> vv = vvOwner.GetSpan();
 
             ref Box cube = ref this.colorCube[0];
             cube.RMin = cube.GMin = cube.BMin = cube.AMin = 0;