c# - パネルに表示されている画像の xy 座標を見つける

Question

現在、パネルを使用して画像を表示しています。マウスを使用して画像をズームおよび移動するロジックを既に実装しています。私の質問は、画像をズームまたは移動するときに、パネルに表示されている画像の一部のみをトリミングして保存したいということです。

画像のズームと移動に使用したコードは次のとおりです。

    namespace ImageZooming
{
    public partial class Form2 : Form
    {
        public class overRidePanel : Panel
        {
            protected override void OnPaintBackground(PaintEventArgs pevent) { }
        }
        Bitmap bitmap;
        BufferedGraphicsContext currentContext;
        BufferedGraphics myBuffer;
        PointF viewPortCenter;
        float Zoom = 1.0f;
        string sFilePath;
        bool draging = false;
        Point lastMouse;
        int cropX;
        int cropY;
        byte[] MyData = new byte[0];
        public Form2()
        {
            InitializeComponent();
            this.panel1.MouseWheel += new MouseEventHandler(panel1_MouseWheel);
            currentContext = BufferedGraphicsManager.Current;
            setup(false);
        }
        private void setup(bool resetViewport)
        {
            if (myBuffer != null)
                myBuffer.Dispose();
            myBuffer = currentContext.Allocate(this.panel1.CreateGraphics(), this.panel1.DisplayRectangle);
            if (bitmap != null)
            {
                if (resetViewport)
                    SetViewPort(new RectangleF(0, 0, bitmap.Width, bitmap.Height));
            }
            this.panel1.Focus();
            this.panel1.Invalidate();
        }
        private void SetViewPort(RectangleF worldCords)
        {
            //Find smallest screen extent and zoom to that
            if (worldCords.Height > worldCords.Width)
            {
                //Use With as limiting factor
                this.Zoom = worldCords.Width / bitmap.Width;
            }
            else
                this.Zoom = worldCords.Height / bitmap.Height;

            viewPortCenter = new PointF(worldCords.X + (worldCords.Width / 2.0f), worldCords.Y + (worldCords.Height / 2.0f));
            //  this.toolStripStatusLabel1.Text = "Zoom: " + ((int)(this.Zoom * 100)).ToString() + "%";

        }
        private void SetViewPort(Rectangle screenCords)
        {
        }
        private void PaintImage()
        {
            if (bitmap != null)
            {
                float widthZoomed = panel1.Width / Zoom;
                float heigthZoomed = panel1.Height / Zoom;

                //Do checks the reason 30,000 is used is because much over this will cause DrawImage to crash
                if (widthZoomed > 30000.0f)
                {
                    Zoom = panel1.Width / 30000.0f;
                    widthZoomed = 30000.0f;
                }
                if (heigthZoomed > 30000.0f)
                {
                    Zoom = panel1.Height / 30000.0f;
                    heigthZoomed = 30000.0f;
                }

                //we stop at 2 because at this point you have almost zoomed into a single pixel
                if (widthZoomed < 2.0f)
                {
                    Zoom = panel1.Width / 2.0f;
                    widthZoomed = 2.0f;
                }
                if (heigthZoomed < 2.0f)
                {
                    Zoom = panel1.Height / 2.0f;
                    heigthZoomed = 2.0f;
                }

                float wz2 = widthZoomed / 2.0f;
                float hz2 = heigthZoomed / 2.0f;
                Rectangle drawRect = new Rectangle(
                    (int)(viewPortCenter.X - wz2),
                    (int)(viewPortCenter.Y - hz2),
                    (int)(widthZoomed),
                    (int)(heigthZoomed));

                //this.toolStripStatusLabel1.Text = "DrawRect = " + drawRect.ToString();

                myBuffer.Graphics.Clear(Color.White); //Clear the Back buffer

                //Draw the image, Write image to back buffer, and render back buffer
                myBuffer.Graphics.DrawImage(bitmap, this.panel1.DisplayRectangle, drawRect, GraphicsUnit.Pixel);
                myBuffer.Render(this.panel1.CreateGraphics());
                // this.label1.Text = "Zoom: " + ((int)(this.Zoom * 100)).ToString() + "%";   //to show zooming %
            }
        }
        private void Form1_Resize(object sender, EventArgs e)
        {
            setup(false);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog fdg = new OpenFileDialog();
            if (fdg.ShowDialog() == DialogResult.OK)
            {
                bitmap = (Bitmap)Bitmap.FromFile(fdg.FileName);
                setup(true);
            }
            sFilePath = fdg.FileName;
        }

        private void panel1_MouseDown(object sender, MouseEventArgs e)
        {

            if (e.Button == MouseButtons.Left)
                draging = true;
        }
       // public Pen cropPen;
        private void panel1_MouseMove(object sender, MouseEventArgs e)
        {
            //cropPen=new Pen(Color.Black,1);
            //cropX = e.X;
            //cropY = e.Y;
            if (draging)
            {

                viewPortCenter = new PointF(viewPortCenter.X + ((lastMouse.X - e.X) / Zoom), viewPortCenter.Y + ((lastMouse.Y - e.Y) / Zoom));
                panel1.Invalidate();
            }
            //panel1.CreateGraphics().DrawRectangle(cropPen, 0, 0, panel1.Width, panel1.Height);
            lastMouse = e.Location;
        }

        private void panel1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
                draging = false;
        }

        private void panel1_Paint(object sender, PaintEventArgs e)
        {
            PaintImage();
        }

        private void panel1_MouseWheel(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            Zoom += Zoom * (e.Delta / 1200.0f); 
            if (e.Delta > 0 && e.Delta < 0) 
                viewPortCenter = new PointF(viewPortCenter.X + ((e.X - (panel1.Width / 2)) / (2 * Zoom)), viewPortCenter.Y + ((e.Y - (panel1.Height / 2)) / (2 * Zoom)));
            this.panel1.Invalidate();
        }