Complete conversion APIs

Author: JimBobSquarePants

src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs

@@ -4,7 +4,6 @@
 using System.Buffers;
 using System.Buffers.Binary;
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Common.Helpers;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.Metadata;

src/ImageSharp/Formats/Bmp/BmpMetadata.cs

@@ -9,7 +9,7 @@ namespace SixLabors.ImageSharp.Formats.Bmp;
 /// <summary>
 /// Provides Bmp specific metadata information for the image.
 /// </summary>
-public class BmpMetadata : IFormatMetadata<BmpMetadata>, IFormatFrameMetadata<BmpMetadata>
+public class BmpMetadata : IFormatMetadata<BmpMetadata>
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="BmpMetadata"/> class.
@@ -66,10 +66,6 @@ public static BmpMetadata FromFormatConnectingMetadata(FormatConnectingMetadata
         };
     }
 
-    /// <inheritdoc/>
-    public static BmpMetadata FromFormatConnectingFrameMetadata(FormatConnectingFrameMetadata metadata)
-        => new();
-
     /// <inheritdoc/>
     public PixelTypeInfo GetPixelTypeInfo()
     {
@@ -140,10 +136,6 @@ public FormatConnectingMetadata ToFormatConnectingMetadata()
             PixelTypeInfo = this.GetPixelTypeInfo()
         };
 
-    /// <inheritdoc/>
-    public FormatConnectingFrameMetadata ToFormatConnectingFrameMetadata()
-        => new();
-
     /// <inheritdoc/>
     IDeepCloneable IDeepCloneable.DeepClone() => this.DeepClone();
 

src/ImageSharp/Formats/Bmp/MetadataExtensions.cs

@@ -0,0 +1,20 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats;
+
+/// <summary>
+/// Provides a way to specify the type of encoding to be used.
+/// </summary>
+public enum EncodingType
+{
+    /// <summary>
+    /// Lossless encoding, which compresses data without any loss of information.
+    /// </summary>
+    Lossless,
+
+    /// <summary>
+    /// Lossy encoding, which compresses data by discarding some of it.
+    /// </summary>
+    Lossy
+}

src/ImageSharp/Formats/EncodingType.cs

@@ -11,7 +11,12 @@ namespace SixLabors.ImageSharp.Formats;
 public class FormatConnectingMetadata
 {
     /// <summary>
-    /// Gets the quality.
+    /// Gets the encoding type.
+    /// </summary>
+    public EncodingType EncodingType { get; init; }
+
+    /// <summary>
+    /// Gets the quality to use when <see cref="EncodingType"/> is <see cref="EncodingType.Lossy"/>.
     /// </summary>
     /// <remarks>
     /// The value is usually between 1 and 100. Defaults to 100.

src/ImageSharp/Formats/FormatConnectingMetadata.cs

@@ -5,8 +5,6 @@
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Formats.Png;
-using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.Metadata.Profiles.Xmp;
@@ -85,7 +83,7 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken
         Guard.NotNull(image, nameof(image));
         Guard.NotNull(stream, nameof(stream));
 
-        GifMetadata gifMetadata = GetGifMetadata(image);
+        GifMetadata gifMetadata = image.Metadata.CloneGifMetadata();
         this.colorTableMode ??= gifMetadata.ColorTableMode;
         bool useGlobalTable = this.colorTableMode == FrameColorTableMode.Global;
 
@@ -178,56 +176,17 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken
         quantized?.Dispose();
     }
 
-    private static GifMetadata GetGifMetadata<TPixel>(Image<TPixel> image)
-        where TPixel : unmanaged, IPixel<TPixel>
-    {
-        if (image.Metadata.TryGetGifMetadata(out GifMetadata? gif))
-        {
-            return gif.DeepClone();
-        }
-
-        if (image.Metadata.TryGetPngMetadata(out PngMetadata? png))
-        {
-            AnimatedImageMetadata ani = png.ToAnimatedImageMetadata();
-            return GifMetadata.FromAnimatedMetadata(ani);
-        }
-
-        if (image.Metadata.TryGetWebpMetadata(out WebpMetadata? webp))
-        {
-            AnimatedImageMetadata ani = webp.ToAnimatedImageMetadata();
-            return GifMetadata.FromAnimatedMetadata(ani);
-        }
-
-        // Return explicit new instance so we do not mutate the original metadata.
-        return new();
-    }
-
     private static GifFrameMetadata GetGifFrameMetadata<TPixel>(ImageFrame<TPixel> frame, int transparencyIndex)
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        GifFrameMetadata? metadata = null;
-        if (frame.Metadata.TryGetGifMetadata(out GifFrameMetadata? gif))
-        {
-            metadata = gif.DeepClone();
-        }
-        else if (frame.Metadata.TryGetPngMetadata(out PngFrameMetadata? png))
-        {
-            AnimatedImageFrameMetadata ani = png.ToAnimatedImageFrameMetadata();
-            metadata = GifFrameMetadata.FromAnimatedMetadata(ani);
-        }
-        else if (frame.Metadata.TryGetWebpFrameMetadata(out WebpFrameMetadata? webp))
-        {
-            AnimatedImageFrameMetadata ani = webp.ToAnimatedImageFrameMetadata();
-            metadata = GifFrameMetadata.FromAnimatedMetadata(ani);
-        }
-
-        if (metadata?.ColorTableMode == FrameColorTableMode.Global && transparencyIndex > -1)
+        GifFrameMetadata metadata = frame.Metadata.CloneGifMetadata();
+        if (metadata.ColorTableMode == FrameColorTableMode.Global && transparencyIndex > -1)
         {
             metadata.HasTransparency = true;
             metadata.TransparencyIndex = ClampIndex(transparencyIndex);
         }
 
-        return metadata ?? new();
+        return metadata;
     }
 
     private void EncodeAdditionalFrames<TPixel>(

src/ImageSharp/Formats/Gif/GifEncoderCore.cs

@@ -69,34 +69,6 @@ private GifMetadata(GifMetadata other)
     /// </summary>
     public IList<string> Comments { get; set; } = [];
 
-    internal static GifMetadata FromAnimatedMetadata(AnimatedImageMetadata metadata)
-    {
-        int index = 0;
-        Color background = metadata.BackgroundColor;
-        if (metadata.ColorTable.HasValue)
-        {
-            ReadOnlySpan<Color> colorTable = metadata.ColorTable.Value.Span;
-            for (int i = 0; i < colorTable.Length; i++)
-            {
-                if (background != colorTable[i])
-                {
-                    continue;
-                }
-
-                index = i;
-                break;
-            }
-        }
-
-        return new()
-        {
-            GlobalColorTable = metadata.ColorTable,
-            ColorTableMode = metadata.ColorTableMode,
-            RepeatCount = metadata.RepeatCount,
-            BackgroundColorIndex = (byte)Numerics.Clamp(index, 0, 255),
-        };
-    }
-
     /// <inheritdoc/>
     public static GifMetadata FromFormatConnectingMetadata(FormatConnectingMetadata metadata)
     {

src/ImageSharp/Formats/Gif/GifMetadata.cs

@@ -20,7 +20,7 @@ public interface IFormatFrameMetadata : IDeepCloneable
 /// </summary>
 /// <typeparam name="TSelf">The metadata type implementing this interface.</typeparam>
 public interface IFormatFrameMetadata<TSelf> : IFormatFrameMetadata, IDeepCloneable<TSelf>
-    where TSelf : class, IFormatFrameMetadata, new()
+    where TSelf : class, IFormatFrameMetadata
 {
     /// <summary>
     /// Creates a new instance of the <typeparamref name="TSelf"/> class from the given <see cref="FormatConnectingFrameMetadata"/>.

src/ImageSharp/Formats/Gif/MetadataExtensions.cs

@@ -28,7 +28,7 @@ public interface IFormatMetadata : IDeepCloneable
 /// </summary>
 /// <typeparam name="TSelf">The metadata type implementing this interface.</typeparam>
 public interface IFormatMetadata<TSelf> : IFormatMetadata, IDeepCloneable<TSelf>
-    where TSelf : class, IFormatMetadata, new()
+    where TSelf : class, IFormatMetadata
 {
     /// <summary>
     /// Creates a new instance of the <typeparamref name="TSelf"/> class from the given <see cref="FormatConnectingMetadata"/>.