Отметки на изображении

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Net;
using System.Windows.Forms;
 
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private readonly List<Marker> _markers = new List<Marker>();
        private readonly Тotification _totification = new Тotification();
        private bool _isDrawTotification = false;
 
        public Form1()
        {
            InitializeComponent();
 
            SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.UserPaint, true);
 
            Marker.Image = Image.FromStream(new WebClient().OpenRead("https://cdn1.iconfinder.com/data/icons/Map-Markers-Icons-Demo-PNG/128/Map-Marker-Marker-Outside-Azure.png"));
            Marker.Size = new Size(64, 64);
        }
 
        protected override void OnMouseClick(MouseEventArgs e)
        {
            base.OnMouseClick(e);
 
            _markers.Add(new Marker { Location = e.Location, Description = $"Marker №{_markers.Count + 1}" });
            Invalidate();
        }
 
        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);
 
            var marker = _markers.FirstOrDefault(m => m.Contains(e.Location));
 
            if (marker != null)
            {
                _totification.Description = marker.Description;
                _totification.Location = e.Location;
 
                _isDrawTotification = true;
            }
            else
                _isDrawTotification = false;
 
            Invalidate();
        }
 
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            
            foreach (var marker in _markers)
                marker.Draw(e.Graphics);
 
            if (_isDrawTotification)
                _totification.Draw(e.Graphics);
        }
    }
 
    class Marker
    {
        public static Image Image { get; set; }
        public static Size Size { get; set; }
 
        public Point Location { get; set; }
 
        public string Description { get; set; }
 
        public bool Contains(Point point)
        {
            return new Rectangle(Location, Image.Size).Contains(point);
        }
 
        public void Draw(Graphics graphics)
        {
            graphics.DrawImage(Image, new Rectangle(Location, Size));
        }
    }
 
    class Тotification
    {
        public string Title { get; set; } = "Title";
        public string Description { get; set; } = "Description";
 
        public Font Font { get; set; } = new Font("Microsoft Sans Serif", 8F);
 
        public Point Location { get; set; }
        public Size Size { get; set; } = new Size(200, 50);
 
        public Color TextColor { get; set; } = Color.Black;
        public Color BorderColor { get; set; } = Color.Black;
        public Color BackgroundColor { get; set; } = Color.LightYellow;
        public bool IsBorderDraw { get; set; } = true;
 
        public void Draw(Graphics graphics)
        {
            var rectangle = new Rectangle(Location, Size);
 
            using (var brushBackground = new SolidBrush(BackgroundColor))
                graphics.FillRectangle(brushBackground, rectangle);
 
            using (var brushText = new SolidBrush(TextColor))
            {
                graphics.DrawString(Title, Font, brushText, rectangle, new StringFormat { LineAlignment = StringAlignment.Near, Alignment = StringAlignment.Center });
                graphics.DrawString(Description, Font, brushText, rectangle, new StringFormat { LineAlignment = StringAlignment.Center, Alignment = StringAlignment.Near });
            }
 
            if (IsBorderDraw)
                using (var penBorder = new Pen(BorderColor))
                    graphics.DrawRectangle(penBorder, rectangle);
        }
    }
}