using System;

​

public class Program

{

    public static void Main()

    {

        var item = new Item()

        {

            X1 = 0,

            X2 = 0,

            X3 = 0,

            X4 = 0,

            Y1 = 0,

            Y2 = 0,

            Y3 = 0,

            Y4 = 0,

        };

        var (bounds, boundPoints) = GrabBountryRectangle(item);

        var whit = new ImageMagick.MagickImage()

        {

            VirtualPixelMethod = ImageMagick.VirtualPixelMethod.Transparent,

            BackgroundColor = ImageMagick.MagickColor.FromRgba(0, 0, 0, 0),

        };

        var whitRatio = whit.Width / (float)whit.Height;

        var preDistortW = (int)Math.Round(Math.Max(bounds.Width, bounds.Height * whitRatio));

        var preDistortH = (int)Math.Round(Math.Max(bounds.Height, bounds.Width * whitRatio));

​

        whit.Scale((uint)preDistortW, (uint)preDistortH);

        var scaledW = whit.Width;

        var scaledH = whit.Height;

​

        whit.Extent((uint)preDistortW, (uint)preDistortH, ImageMagick.Gravity.Northwest);

        whit.Distort(ImageMagick.DistortMethod.Perspective, new double[] {

            0, 0, boundPoints.X1, boundPoints.Y1,

            0, scaledH, boundPoints.X2, boundPoints.Y2,

            scaledW, 0, boundPoints.X3, boundPoints.Y3,

            scaledW, scaledH, boundPoints.X4, boundPoints.Y4,

        });

    }

    private static (System.Drawing.Rectangle, FourPoints) GrabBountryRectangle(Item item)

        {

            var roundX1 = (int)Math.Round(item.X1);

            var roundY1 = (int)Math.Round(item.Y1);

            var roundX2 = (int)Math.Round(item.X2);

            var roundY2 = (int)Math.Round(item.Y2);

            var roundX3 = (int)Math.Round(item.X3);

            var roundY3 = (int)Math.Round(item.Y3);

            var roundX4 = (int)Math.Round(item.X4);

            var roundY4 = (int)Math.Round(item.Y4);

​

            var left = Math.Min(Math.Min(roundX1, roundX2), Math.Min(roundX3, roundX4));

            var right = Math.Max(Math.Max(roundX1, roundX2), Math.Max(roundX3, roundX4));

            var top = Math.Min(Math.Min(roundY1, roundY2), Math.Min(roundY3, roundY4));

            var bottom = Math.Max(Math.Max(roundY1, roundY2), Math.Max(roundY3, roundY4));

​

            var bounds = new System.Drawing.Rectangle(left, top, right - left, bottom - top);

            var boundPoints = new FourPoints

            {

                X1 = roundX1 - left,

                Y1 = roundY1 - top,

                X2 = roundX2 - left,

                Y2 = roundY2 - top,

                X3 = roundX3 - left,

                Y3 = roundY3 - top,

                X4 = roundX4 - left,

                Y4 = roundY4 - top,

            };

​

            return (bounds, boundPoints);

        }

}

​

public class FourPoints

        {

            public int X1 { get; set; }

            public int Y1 { get; set; }

            public int X2 { get; set; }

            public int Y2 { get; set; }

            public int X3 { get; set; }

            public int Y3 { get; set; }

            public int X4 { get; set; }

            public int Y4 { get; set; }

​

            public void Scale(double s, int offsetX = 0, int offsetY = 0)

            {

                X1 = (int)Math.Round(X1 * s) + offsetX;

                Y1 = (int)Math.Round(Y1 * s) + offsetY;

                X2 = (int)Math.Round(X2 * s) + offsetX;

                Y2 = (int)Math.Round(Y2 * s) + offsetY;

                X3 = (int)Math.Round(X3 * s) + offsetX;

                Y3 = (int)Math.Round(Y3 * s) + offsetY;

                X4 = (int)Math.Round(X4 * s) + offsetX;

                Y4 = (int)Math.Round(Y4 * s) + offsetY;

            }

        }

​

public class Item

    {

​

        public float X1 { get; set; }

​

        public float Y1 { get; set; }

​

        public float X2 { get; set; }

​

        public float Y2 { get; set; }

​

        public float X3 { get; set; }

​

        public float Y3 { get; set; }

​

        public float X4 { get; set; }

​

        public float Y4 { get; set; }

    }

​