C# 从路径中获取图像缩略图

在我的xamarin.mac应用程序中，我使用SQLite保存数据库，配置文件图片也保存在数据库中，但我在处理大图像（例如大小为4 MB）时遇到问题，我只需要保存照片的缩略图，同时上传：

imgProfilePicture.Image = new NSImage (path);
Byte [] bytes = System.IO.File.ReadAllBytes (path);
_profilePic = Convert.ToBase64String (bytes);

我将base64字符串保存在db中。。同样，c#中的简单解是：

我需要这样的东西，需要调整图像大小而不裁剪它

        NSImage baseImage = new NSImage ("original.jpg", false);
        NSImage tinyImage = new NSImage (new CoreGraphics.CGSize (32, 32));
        tinyImage.LockFocus ();
        baseImage.DrawInRect (new CoreGraphics.CGRect (0, 0, 32, 32), new CoreGraphics.CGRect (0, 0, baseImage.Size.Width, baseImage.Size.Height), NSCompositingOperation.Copy, 1.0f);
        tinyImage.UnlockFocus ();

        NSBitmapImageRep rep = new NSBitmapImageRep (tinyImage.AsTiff ());
        NSData data = rep.RepresentationUsingTypeProperties (NSBitmapImageFileType.Jpeg);
        data.Save ("tiny.jpg", true);

转换为C#

转换为C#

        NSImage baseImage = new NSImage ("original.jpg", false);
        NSImage tinyImage = new NSImage (new CoreGraphics.CGSize (32, 32));
        tinyImage.LockFocus ();
        baseImage.DrawInRect (new CoreGraphics.CGRect (0, 0, 32, 32), new CoreGraphics.CGRect (0, 0, baseImage.Size.Width, baseImage.Size.Height), NSCompositingOperation.Copy, 1.0f);
        tinyImage.UnlockFocus ();

        NSBitmapImageRep rep = new NSBitmapImageRep (tinyImage.AsTiff ());
        NSData data = rep.RepresentationUsingTypeProperties (NSBitmapImageFileType.Jpeg);
        data.Save ("tiny.jpg", true);