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ZelWiki.Library/Images.cs

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+using ImageMagick;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Processing;
+
+namespace ZelWiki.Library
+{
+    public static class Images
+    {
+        public enum ImageFormat
+        {
+            Png,
+            Jpeg,
+            Bmp,
+            Tiff,
+            Gif
+        }
+
+        public static byte[] ResizeGifImage(byte[] imageBytes, int width, int height)
+        {
+            using var imageCollection = new MagickImageCollection(imageBytes);
+
+            if (imageCollection.Count > 10)
+            {
+                Parallel.ForEach(imageCollection, frame =>
+                {
+                    frame.Sample((uint)width, (uint)height);
+                });
+            }
+            else
+            {
+                Parallel.ForEach(imageCollection, frame =>
+                {
+                    frame.Resize((uint)width, (uint)height);
+                });
+            }
+
+            return imageCollection.ToByteArray();
+        }
+
+        public static Image ResizeImage(Image image, int width, int height)
+        {
+            image.Mutate(x => x.Resize(width, height));
+            return image;
+        }
+
+        public static string BestEffortConvertImage(Image image, MemoryStream ms, string preferredContentType)
+        {
+            switch (preferredContentType.ToLower())
+            {
+                case "image/png":
+                    image.SaveAsPng(ms);
+                    return preferredContentType;
+                case "image/jpeg":
+                    image.SaveAsJpeg(ms);
+                    return preferredContentType;
+                case "image/bmp":
+                    image.SaveAsBmp(ms);
+                    return preferredContentType;
+                case "image/gif":
+                    throw new NotImplementedException("Use [ResizeGifImage] for saving animated images.");
+                //image.SaveAsGif(ms);
+                //return preferredContentType;
+                case "image/tiff":
+                    image.SaveAsTiff(ms);
+                    return preferredContentType;
+                default:
+                    image.SaveAsPng(ms);
+                    return "image/png";
+            }
+        }
+    }
+}