Moved various properties from the encoder/decoder to the image format.

src/ImageSharp/Formats/Bmp/BmpDecoder.cs

@@ -31,24 +31,6 @@ namespace ImageSharp.Formats
         /// <value>The size of the header.</value>
         public int HeaderSize => 2;
 
-        /// <summary>
-        /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
-        /// file header.
-        /// </summary>
-        /// <param name="extension">The <see cref="string"/> containing the file extension.</param>
-        /// <returns>
-        /// True if the decoder supports the file extension; otherwise, false.
-        /// </returns>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, "extension");
-
-            extension = extension.StartsWith(".") ? extension.Substring(1) : extension;
-
-            return extension.Equals("BMP", StringComparison.OrdinalIgnoreCase)
-                || extension.Equals("DIP", StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <summary>
         /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
         /// file header.

src/ImageSharp/Formats/Bmp/BmpEncoder.cs

@@ -14,34 +14,11 @@ namespace ImageSharp.Formats
     /// <remarks>The encoder can currently only write 24-bit rgb images to streams.</remarks>
     public class BmpEncoder : IImageEncoder
     {
-        /// <summary>
-        /// Gets or sets the quality of output for images.
-        /// </summary>
-        /// <remarks>Bitmap is a lossless format so this is not used in this encoder.</remarks>
-        public int Quality { get; set; }
-
-        /// <inheritdoc/>
-        public string MimeType => "image/bmp";
-
-        /// <inheritdoc/>
-        public string Extension => "bmp";
-
         /// <summary>
         /// Gets or sets the number of bits per pixel.
         /// </summary>
         public BmpBitsPerPixel BitsPerPixel { get; set; } = BmpBitsPerPixel.Pixel24;
 
-        /// <inheritdoc/>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, nameof(extension));
-
-            extension = extension.StartsWith(".") ? extension.Substring(1) : extension;
-
-            return extension.Equals(this.Extension, StringComparison.OrdinalIgnoreCase)
-                || extension.Equals("dip", StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <inheritdoc/>
         public void Encode<TColor, TPacked>(Image<TColor, TPacked> image, Stream stream)
             where TColor : struct, IPackedPixel<TPacked>

src/ImageSharp/Formats/Bmp/BmpFormat.cs

@@ -5,11 +5,22 @@
 
 namespace ImageSharp.Formats
 {
+    using System.Collections.Generic;
+
     /// <summary>
     /// Encapsulates the means to encode and decode bitmap images.
     /// </summary>
     public class BmpFormat : IImageFormat
     {
+        /// <inheritdoc/>
+        public string MimeType => "image/bmp";
+
+        /// <inheritdoc/>
+        public string Extension => "bmp";
+
+        /// <inheritdoc/>
+        public IEnumerable<string> SupportedExtensions => new string[] { "bmp", "dip" };
+
         /// <inheritdoc/>
         public IImageDecoder Decoder => new BmpDecoder();
 

src/ImageSharp/Formats/Gif/GifDecoder.cs

@@ -19,22 +19,6 @@ namespace ImageSharp.Formats
         /// <value>The size of the header.</value>
         public int HeaderSize => 6;
 
-        /// <summary>
-        /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
-        /// file header.
-        /// </summary>
-        /// <param name="extension">The <see cref="string"/> containing the file extension.</param>
-        /// <returns>
-        /// True if the decoder supports the file extension; otherwise, false.
-        /// </returns>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, nameof(extension));
-
-            extension = extension.StartsWith(".") ? extension.Substring(1) : extension;
-            return extension.Equals("GIF", StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <summary>
         /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
         /// file header.

src/ImageSharp/Formats/Gif/GifEncoder.cs

@@ -31,21 +31,6 @@ namespace ImageSharp.Formats
         /// </summary>
         public IQuantizer Quantizer { get; set; }
 
-        /// <inheritdoc/>
-        public string Extension => "gif";
-
-        /// <inheritdoc/>
-        public string MimeType => "image/gif";
-
-        /// <inheritdoc/>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, nameof(extension));
-
-            extension = extension.StartsWith(".") ? extension.Substring(1) : extension;
-            return extension.Equals(this.Extension, StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <inheritdoc/>
         public void Encode<TColor, TPacked>(Image<TColor, TPacked> image, Stream stream)
         where TColor : struct, IPackedPixel<TPacked>

src/ImageSharp/Formats/Gif/GifFormat.cs

@@ -5,11 +5,22 @@
 
 namespace ImageSharp.Formats
 {
+    using System.Collections.Generic;
+
     /// <summary>
     /// Encapsulates the means to encode and decode gif images.
     /// </summary>
     public class GifFormat : IImageFormat
     {
+        /// <inheritdoc/>
+        public string Extension => "gif";
+
+        /// <inheritdoc/>
+        public string MimeType => "image/gif";
+
+        /// <inheritdoc/>
+        public IEnumerable<string> SupportedExtensions => new string[] { "gif" };
+
         /// <inheritdoc/>
         public IImageDecoder Decoder => new GifDecoder();
 

src/ImageSharp/Formats/IImageDecoder.cs

@@ -19,16 +19,6 @@ namespace ImageSharp.Formats
         /// <value>The size of the header.</value>
         int HeaderSize { get; }
 
-        /// <summary>
-        /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
-        /// file header.
-        /// </summary>
-        /// <param name="extension">The <see cref="string"/> containing the file extension.</param>
-        /// <returns>
-        /// True if the decoder supports the file extension; otherwise, false.
-        /// </returns>
-        bool IsSupportedFileExtension(string extension);
-
         /// <summary>
         /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
         /// file header.

src/ImageSharp/Formats/IImageEncoder.cs

@@ -13,31 +13,6 @@ namespace ImageSharp.Formats
     /// </summary>
     public interface IImageEncoder
     {
-        /// <summary>
-        /// Gets or sets the quality of output for images.
-        /// </summary>
-        int Quality { get; set; }
-
-        /// <summary>
-        /// Gets the standard identifier used on the Internet to indicate the type of data that a file contains.
-        /// </summary>
-        string MimeType { get; }
-
-        /// <summary>
-        /// Gets the default file extension for this encoder.
-        /// </summary>
-        string Extension { get; }
-
-        /// <summary>
-        /// Returns a value indicating whether the <see cref="IImageEncoder"/> supports the specified
-        /// file header.
-        /// </summary>
-        /// <param name="extension">The <see cref="string"/> containing the file extension.</param>
-        /// <returns>
-        /// <c>True</c> if the decoder supports the file extension; otherwise, <c>false</c>.
-        /// </returns>
-        bool IsSupportedFileExtension(string extension);
-
         /// <summary>
         /// Encodes the image to the specified stream from the <see cref="Image{TColor, TPacked}"/>.
         /// </summary>

src/ImageSharp/Formats/IImageFormat.cs

@@ -5,11 +5,31 @@
 
 namespace ImageSharp.Formats
 {
+    using System.Collections.Generic;
+
     /// <summary>
     /// Encapsulates a supported image format, providing means to encode and decode an image.
     /// </summary>
     public interface IImageFormat
     {
+        /// <summary>
+        /// Gets the standard identifier used on the Internet to indicate the type of data that a file contains.
+        /// </summary>
+        string MimeType { get; }
+
+        /// <summary>
+        /// Gets the default file extension for this format.
+        /// </summary>
+        string Extension { get; }
+
+        /// <summary>
+        /// Gets the supported file extensions for this format.
+        /// </summary>
+        /// <returns>
+        /// The supported file extension.
+        /// </returns>
+        IEnumerable<string> SupportedExtensions { get; }
+
         /// <summary>
         /// Gets the image encoder for encoding an image from a stream.
         /// </summary>

src/ImageSharp/Formats/Jpg/JpegDecoder.cs

@@ -19,33 +19,6 @@ namespace ImageSharp.Formats
         /// <value>The size of the header.</value>
         public int HeaderSize => 11;
 
-        /// <summary>
-        /// Indicates if the image decoder supports the specified
-        /// file extension.
-        /// </summary>
-        /// <param name="extension">The file extension.</param>
-        /// <returns>
-        /// <c>true</c>, if the decoder supports the specified
-        /// extensions; otherwise <c>false</c>.
-        /// </returns>
-        /// <exception cref="System.ArgumentNullException"><paramref name="extension"/>
-        /// is null (Nothing in Visual Basic).</exception>
-        /// <exception cref="System.ArgumentException"><paramref name="extension"/> is a string
-        /// of length zero or contains only blanks.</exception>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, "extension");
-
-            if (extension.StartsWith("."))
-            {
-                extension = extension.Substring(1);
-            }
-
-            return extension.Equals("JPG", StringComparison.OrdinalIgnoreCase) ||
-                   extension.Equals("JPEG", StringComparison.OrdinalIgnoreCase) ||
-                   extension.Equals("JFIF", StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <summary>
         /// Indicates if the image decoder supports the specified
         /// file header.

src/ImageSharp/Formats/Jpg/JpegEncoder.cs

@@ -60,27 +60,6 @@ namespace ImageSharp.Formats
             }
         }
 
-        /// <inheritdoc/>
-        public string MimeType => "image/jpeg";
-
-        /// <inheritdoc/>
-        public string Extension => "jpg";
-
-        /// <inheritdoc/>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, "extension");
-
-            if (extension.StartsWith("."))
-            {
-                extension = extension.Substring(1);
-            }
-
-            return extension.Equals(this.Extension, StringComparison.OrdinalIgnoreCase) ||
-                   extension.Equals("jpeg", StringComparison.OrdinalIgnoreCase) ||
-                   extension.Equals("jfif", StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <inheritdoc/>
         public void Encode<TColor, TPacked>(Image<TColor, TPacked> image, Stream stream)
             where TColor : struct, IPackedPixel<TPacked>

src/ImageSharp/Formats/Jpg/JpegFormat.cs

@@ -5,11 +5,22 @@
 
 namespace ImageSharp.Formats
 {
+    using System.Collections.Generic;
+
     /// <summary>
     /// Encapsulates the means to encode and decode jpeg images.
     /// </summary>
     public class JpegFormat : IImageFormat
     {
+        /// <inheritdoc/>
+        public string MimeType => "image/jpeg";
+
+        /// <inheritdoc/>
+        public string Extension => "jpg";
+
+        /// <inheritdoc/>
+        public IEnumerable<string> SupportedExtensions => new string[] { "jpg", "jpeg", "jfif" };
+
         /// <inheritdoc/>
         public IImageDecoder Decoder => new JpegDecoder();
 

src/ImageSharp/Formats/Png/PngDecoder.cs

@@ -36,23 +36,6 @@ namespace ImageSharp.Formats
         /// <value>The size of the header.</value>
         public int HeaderSize => 8;
 
-        /// <summary>
-        /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
-        /// file header.
-        /// </summary>
-        /// <param name="extension">The <see cref="string"/> containing the file extension.</param>
-        /// <returns>
-        /// True if the decoder supports the file extension; otherwise, false.
-        /// </returns>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, "extension");
-
-            extension = extension.StartsWith(".") ? extension.Substring(1) : extension;
-
-            return extension.Equals("PNG", StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <summary>
         /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
         /// file header.

src/ImageSharp/Formats/Png/PngEncoder.cs

@@ -25,12 +25,6 @@ namespace ImageSharp.Formats
         /// </summary>
         public PngColorType PngColorType { get; set; } = PngColorType.RgbWithAlpha;
 
-        /// <inheritdoc/>
-        public string MimeType => "image/png";
-
-        /// <inheritdoc/>
-        public string Extension => "png";
-
         /// <summary>
         /// Gets or sets the compression level 1-9.
         /// <remarks>Defaults to 6.</remarks>
@@ -61,16 +55,6 @@ namespace ImageSharp.Formats
         /// </summary>
         public bool WriteGamma { get; set; }
 
-        /// <inheritdoc/>
-        public bool IsSupportedFileExtension(string extension)
-        {
-            Guard.NotNullOrEmpty(extension, nameof(extension));
-
-            extension = extension.StartsWith(".") ? extension.Substring(1) : extension;
-
-            return extension.Equals(this.Extension, StringComparison.OrdinalIgnoreCase);
-        }
-
         /// <inheritdoc/>
         public void Encode<TColor, TPacked>(Image<TColor, TPacked> image, Stream stream)
             where TColor : struct, IPackedPixel<TPacked>

src/ImageSharp/Formats/Png/PngFormat.cs

@@ -5,11 +5,22 @@
 
 namespace ImageSharp.Formats
 {
+    using System.Collections.Generic;
+
     /// <summary>
     /// Encapsulates the means to encode and decode png images.
     /// </summary>
     public class PngFormat : IImageFormat
     {
+        /// <inheritdoc/>
+        public string MimeType => "image/png";
+
+        /// <inheritdoc/>
+        public string Extension => "png";
+
+        /// <inheritdoc/>
+        public IEnumerable<string> SupportedExtensions => new string[] { "png" };
+
         /// <inheritdoc/>
         public IImageDecoder Decoder => new PngDecoder();
 

src/ImageSharp/Image/Image.cs

@@ -255,7 +255,7 @@ namespace ImageSharp
             {
                 this.Save(stream);
                 stream.Flush();
-                return $"data:{this.CurrentImageFormat.Encoder.MimeType};base64,{Convert.ToBase64String(stream.ToArray())}";
+                return $"data:{this.CurrentImageFormat.MimeType};base64,{Convert.ToBase64String(stream.ToArray())}";
             }
         }