2chBackAPI/DBControllers/ImageController.cs

using SkiaSharp;

namespace NeDvachAPI.DBControllers
{
    public class ImageController
    {
        public static bool CheckExtention(string extentionToCheck)
        {
            var supportedTypes = new[] { ".jpg", ".png", ".jpeg" };
            if (supportedTypes.Contains(extentionToCheck.ToLower()))
            {
                return true;
            }
            else return false;
        }

    public static bool ResizeImage(string picPath, string smallPath, int width, int height)
        {

            var bitmap = SKBitmap.Decode(picPath);

            double ratio = Math.Max((double)bitmap.Width / (double)width , (double)bitmap.Height / (double)height);
            int targetWidth = (int)(bitmap.Width/ ratio);
            int targetHeight = (int)(bitmap.Height / ratio);

            Console.WriteLine($"Ресайзим картинку до {targetWidth} ширины и {targetHeight} высоты.");

            var dstInfo = new SKImageInfo(targetWidth , targetHeight);
            var image = SKImage.FromBitmap(bitmap.Resize(dstInfo, SKFilterQuality.Medium));
            var data = image.Encode(SKEncodedImageFormat.Jpeg, 90);

             using (var stream = new FileStream(smallPath, FileMode.Create, FileAccess.Write))
                 data.SaveTo(stream);

            data.Dispose();
            image.Dispose();
            bitmap.Dispose();
            return true;
        }
    }
}