Define base classes and options

src/ImageSharp/Formats/IEncoderOptions.cs

@@ -0,0 +1,33 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Processing.Processors.Quantization;
+
+namespace SixLabors.ImageSharp.Formats;
+
+/// <summary>
+/// Defines the contract for basic encoder options.
+/// </summary>
+public interface IEncoderOptions
+{
+    /// <summary>
+    /// Gets or sets a value indicating whether to ignore decoded metadata when encoding.
+    /// </summary>
+    bool SkipMetadata { get; set; }
+}
+
+/// <summary>
+/// Defines the contract for encoder options that allow color palette generation via quantization.
+/// </summary>
+public interface IQuantizingEncoderOptions : IEncoderOptions
+{
+    /// <summary>
+    /// Gets or sets the quantizer used to generate the color palette.
+    /// </summary>
+    IQuantizer Quantizer { get; set; }
+
+    /// <summary>
+    /// Gets or sets the <see cref="IPixelSamplingStrategy"/> used for quantization when building a global color palette.
+    /// </summary>
+    IPixelSamplingStrategy GlobalPixelSamplingStrategy { get; set; }
+}

src/ImageSharp/Formats/ImageDecoderUtilities.cs

@@ -58,7 +58,7 @@ internal static class ImageDecoderUtilities
         Stream stream,
         CancellationToken cancellationToken)
     {
-        using var bufferedReadStream = new BufferedReadStream(configuration, stream);
+        using BufferedReadStream bufferedReadStream = new(configuration, stream);
 
         try
         {
@@ -86,7 +86,7 @@ internal static class ImageDecoderUtilities
         CancellationToken cancellationToken)
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        using var bufferedReadStream = new BufferedReadStream(configuration, stream);
+        using BufferedReadStream bufferedReadStream = new(configuration, stream);
 
         try
         {

src/ImageSharp/Formats/ImageEncoder.cs

@@ -0,0 +1,37 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+using SixLabors.ImageSharp.Processing.Processors.Quantization;
+
+namespace SixLabors.ImageSharp.Formats;
+
+/// <summary>
+/// The base class for all image encoders.
+/// </summary>
+public abstract class ImageEncoder : IImageEncoder, IEncoderOptions
+{
+    /// <inheritdoc/>
+    public bool SkipMetadata { get; set; }
+
+    /// <inheritdoc/>
+    public abstract void Encode<TPixel>(Image<TPixel> image, Stream stream)
+        where TPixel : unmanaged, IPixel<TPixel>;
+
+    /// <inheritdoc/>
+    public abstract Task EncodeAsync<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
+        where TPixel : unmanaged, IPixel<TPixel>;
+}
+
+/// <summary>
+/// The base class for all image encoders that allow color palette generation via quantization.
+/// </summary>
+public abstract class QuantizingImageEncoder : ImageEncoder, IQuantizingEncoderOptions
+{
+    /// <inheritdoc/>
+    public IQuantizer Quantizer { get; set; } = KnownQuantizers.Octree;
+
+    /// <inheritdoc/>
+    public IPixelSamplingStrategy GlobalPixelSamplingStrategy { get; set; } = new DefaultPixelSamplingStrategy();
+}

src/ImageSharp/Formats/ImageEncoderUtilities.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
 using SixLabors.ImageSharp.Advanced;
@@ -22,11 +22,11 @@ internal static class ImageEncoderUtilities
         }
         else
         {
-            using var ms = new MemoryStream();
+            using MemoryStream ms = new();
             await DoEncodeAsync(ms);
             ms.Position = 0;
             await ms.CopyToAsync(stream, configuration.StreamProcessingBufferSize, cancellationToken)
-                .ConfigureAwait(false);
+                    .ConfigureAwait(false);
         }
 
         Task DoEncodeAsync(Stream innerStream)