qrcode/Program.cs

using OpenCvSharp;
using ZXing;
using ZXing.QrCode;
using OpenCvSharp.Extensions;
using ZXing.Windows.Compatibility;
using ZXing.Common;
using System.Runtime.InteropServices;
using System.Drawing;


namespace BarcodeReaderExample
{
    class Program
    {
        static void Main(string[] args)
        {
            VideoCapture camera = new VideoCapture("/dev/video0", VideoCaptureAPIs.V4L2);

            if (!camera.IsOpened())
                throw new Exception("Nie można otworzyć kamery /dev/video0");

            camera.Set(VideoCaptureProperties.FrameWidth, 1280);
            camera.Set(VideoCaptureProperties.FrameHeight, 720);
            camera.Set(VideoCaptureProperties.Fps, 5);


            Mat hey = new Mat("photo.png");



            using var rgb = new Mat();

            // OpenCV stores camera frames as BGR.
            // ZXing's RGBLuminanceSource expects RGB.
            // Cv2.CvtColor(frame, rgb, ColorConversionCodes.BGR2RGB);



            Cv2.NamedWindow("Camera preview", WindowFlags.AutoSize);
            int photocount = 0;


            while (true)
            {
                // if (!camera.Read(frame) || frame.Empty())
                // {
                //     Console.Error.WriteLine("Nie udało się odczytać klatki");
                //     break;
                // }
                camera.Read(frame);


                Result result = GetResult(frame);
                if (result != null)
                {
                    List<ResultPoint> points = result.ResultPoints.ToList();
                    float[] pos1 =   new float[2] {points[0].X, points[0].Y}; /// lewy dolny róg
                    float[] pos2 =   new float[2] {points[2].X, points[2].Y};   ///prawy górny róg
                    float[] pos3 = new float[2] { points[1].X, points[1].Y };   ///lewy górny róg

                    // Cv2.Circle(frame, (int)pos1[0], (int)pos1[1], 5, Scalar.Red, 2);
                    // Cv2.Circle(frame, (int)pos2[0], (int)pos2[1], 5, Scalar.Green, 2);
                    // Cv2.Circle(frame, (int)pos3[0], (int)pos3[1], 5, Scalar.Blue, 2);  

                    
                    Calculate(pos1, pos2, pos3, new float[2] { points[3].X, points[3].Y });


                    // Cv2.Circle(frame, (int)(RightBottomX), (int)(RightBottomY), 5, Scalar.Green, 2);  

                    //Cv2.Rectangle(frame, new Point((int)X, (int)Y), new Point ((int)Width, (int)Height), Scalar.Red, 2); 
                    Console.WriteLine(result.Text);
                }



                // frame.SaveImage($"photos/photo_{photocount}.png");
                // photocount++;


                Cv2.ImShow("Camera preview", frame);
                Thread.Sleep(1000 / 24);
                // Console.WriteLine("tick");
                int key = Cv2.WaitKey(1);
                if (key == 27 || key == 'q')
                    break;
            }

            Cv2.DestroyAllWindows();

        }
        static void Calculate(float[] pos1, float[] pos2, float[] pos3, float[] pos4)
        {
            // Your 4 detected points (change the names if needed)
PointF p1 = new PointF(pos1[0], pos1[1]);
PointF p2 = new PointF(pos2[0], pos2[1]);
PointF p3 = new PointF(pos3[0], pos3[1]);
PointF p4 = new PointF(pos4[0], pos4[1]);

// 1. Find the center of the QR
float centerX = (p1.X + p2.X + p3.X + p4.X) / 4f;
float centerY = (p1.Y + p2.Y + p3.Y + p4.Y) / 4f;
PointF center = new PointF(centerX, centerY);

// 2. How much bigger you want the box (1.0 = exact size, 1.15 = 15% bigger)
float scale = 1.35f;   // ← change this value

// 3. Move every corner away from the center
PointF Expand(PointF p)
{
    float dx = p.X - center.X;
    float dy = p.Y - center.Y;
    return new PointF(center.X + dx * scale, center.Y + dy * scale);
}

float scaleLB = 1.75f;   // ← change this value
PointF ExpandLB(PointF p)
{
    float dx = p.X - center.X;
    float dy = p.Y - center.Y;
    return new PointF(center.X + dx * scaleLB, center.Y + dy * scaleLB);
}

PointF topLeft     = Expand(p3);   // change order if needed
PointF topRight    = Expand(p2);
PointF bottomRight = ExpandLB(p4);
PointF bottomLeft  = Expand(p1);

// 4. Now draw the 4 lines
// Example with System.Drawing or Unity or whatever you use:
DrawLine(topLeft, topRight);
DrawLine(topRight, bottomRight);
DrawLine(bottomRight, bottomLeft);
DrawLine(bottomLeft, topLeft);
        }
        static void DrawLine(PointF p1, PointF p2)
        {
            Cv2.Line(frame, (int)p1.X, (int)p1.Y, (int)p2.X, (int)p2.Y, Scalar.Red, 2);

        }
        static void DrawLine(float x1, float y1, float x2, float y2)
        {
            Cv2.Line(frame, (int)x1, (int)y1, (int)x2, (int)y2, Scalar.Red, 2);
        }
        static Mat frame = new Mat();

        static Result GetResult(Mat frame)
        {

            QRCodeReader reader = new QRCodeReader();
            Result result = reader.decode(MatToBinaryBitmap(frame));
            return result;
        }
        static BinaryBitmap MatToBinaryBitmap(Mat frame)
        {
            if (frame.Empty())
                throw new ArgumentException("The Mat is empty.", nameof(frame));

            using var rgb = new Mat();

            // OpenCV uses BGR; ZXing RGBLuminanceSource expects RGB.
            Cv2.CvtColor(
                frame,
                rgb,
                ColorConversionCodes.BGR2RGB
            );

            // Clone ensures contiguous pixel memory.
            using var contiguous = rgb.Clone();

            int width = contiguous.Width;
            int height = contiguous.Height;

            int byteCount = checked(
                (int)(contiguous.Total() * contiguous.ElemSize())
            );

            byte[] pixels = new byte[byteCount];

            Marshal.Copy(
                contiguous.Data,
                pixels,
                0,
                pixels.Length
            );

            var luminanceSource = new RGBLuminanceSource(
                pixels,
                width,
                height,
                RGBLuminanceSource.BitmapFormat.RGB24
            );

            return new BinaryBitmap(
                new HybridBinarizer(luminanceSource)
            );
        }
    }
}