Added user image caching

src/Helpers/ImageHelper.cs

@@ -1,5 +1,4 @@
 using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Formats;
 
@@ -7,36 +6,33 @@ namespace Berufsschule_HAM.Helpers;
 
 public static class ImageHelper
 {
-    public static string ResizeAndConvertToBase64(byte[] imageBytes, int size = 32)
+    public static Dictionary<int, Dictionary<string, byte[]>> ImageCache = [];
+    public static byte[] ResizeAndConvertToWebp(string imageString, int size = 32)
     {
-        using var inputStream = new MemoryStream(imageBytes);
-
-        var decoderOptions = new DecoderOptions
+        if (ImageCache.TryGetValue(size, out Dictionary<string, byte[]>? sizeCache)
+        && sizeCache.TryGetValue(imageString, out byte[]? result) && result.Length > 0)
         {
-            TargetSize = new Size(size, size)
-        };
-
-        using var image = Image.Load(decoderOptions, inputStream);
-
-        int minDimension = Math.Min(image.Width, image.Height);
-        var cropRectangle = new Rectangle(
-            (image.Width - minDimension) / 2,
-            (image.Height - minDimension) / 2,
-            minDimension,
-            minDimension);
-
-        image.Mutate(x =>
+            return result;
+        }
+        if (sizeCache is null) ImageCache[size] = [];
+        lock (ImageCache[size])
         {
-            x.Crop(cropRectangle);
-            x.Resize(new ResizeOptions
+            byte[] imageBytes = Convert.FromBase64String(imageString);
+            using var inputStream = new MemoryStream(imageBytes);
+
+            var decoderOptions = new DecoderOptions
             {
-                Size = new Size(size, size),
-                Mode = ResizeMode.Crop
-            });
-        });
+                TargetSize = new Size(size, size),
+                SkipMetadata = true
+            };
 
-        using var outputStream = new MemoryStream();
-        image.Save(outputStream, new WebpEncoder());
-        return Convert.ToBase64String(outputStream.GetBuffer(), 0, (int)outputStream.Length);
+            using var image = Image.Load(decoderOptions, inputStream);
+
+            using var outputStream = new MemoryStream();
+            image.Save(outputStream, new WebpEncoder());
+            result = outputStream.ToArray();
+            ImageCache[size][imageString] = result;
+        }
+        return result;
     }
 }