add support to encode images for GPT 4 vision models

src/Microsoft.DotNet.Interactive.AIUtilities/Image.cs

@@ -0,0 +1,37 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using Pocket;
+using SkiaSharp;
+
+namespace Microsoft.DotNet.Interactive.AIUtilities;
+
+using Logger = Pocket.Logger<SKImage>;
+
+public static class Image {
+    /// <summary>
+    /// Generates a base64 encoded string for the image.
+    /// </summary>
+    /// <param name="image"></param>
+    /// <returns>The base64 encoding of the image as png</returns>
+    public static string ToBase64(this SKImage image)
+    {
+        Logger.Log.Event();
+        var encoded = image.Encode(SKEncodedImageFormat.Png, 100);
+        return Convert.ToBase64String(encoded.ToArray());
+    }
+
+    /// <summary>
+    /// Generates a data URI for the image.
+    /// This can be used in the src attribute of an img tag to display the image in a browser.
+    /// </summary>
+    /// <param name="image"></param>
+    /// <returns>A string in the format data:image/jpeg;base64,{base64EncodedImage}</returns>
+    public static string ToImageSrc(this SKImage image)
+    {
+        Logger.Log.Event();
+        var base64Image = image.ToBase64();
+        return $"data:image/png;base64,{base64Image}";
+    }
+}

src/Microsoft.DotNet.Interactive.AIUtilities/Microsoft.DotNet.Interactive.AIUtilities.csproj

@@ -15,6 +15,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.DeepDev.TokenizerLib" Version="1.3.2" />
+    <PackageReference Include="SkiaSharp" Version="2.88.6" />
     <PackageReference Include="System.Reactive" Version="$(SystemReactiveVersion)" />
     <PackageReference Include="System.Text.Json" Version="8.0.0" />
     <PackageReference Include="PocketLogger" Version="0.8.2">