代码展示：C#点击button后在 picturebox上按住鼠标左键拖动鼠标画矩形，松开鼠标左键矩形绘制完成，可以画多个矩形，并且可以选中矩形拖动位置和改变大小，并将矩形点位放在datagridview控件里，可以画多个矩形放在集合里序列化保存和反序列化加载

以下是一个实现上述功能的C#代码示例：

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace DrawRectangles
{
    public partial class MainForm : Form
    {
        private bool isDrawing = false;
        private bool isSelecting = false;
        private Point startPoint;
        private Point endPoint;
        private List<Rectangle> rectangles = new List<Rectangle>();
        private int selectedRectangleIndex = -1;

        public MainForm()
        {
            InitializeComponent();
            dataGridView1.Columns.Add(new DataGridViewTextBoxColumn() { Name = "Rectangles", HeaderText = "Rectangles" });
            dataGridView1.SelectionChanged += DataGridView1_SelectionChanged;
            dataGridView1.CellEndEdit += DataGridView1_CellEndEdit;
        }

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                if (!isSelecting)
                {
                    startPoint = e.Location;
                    isDrawing = true;
                }
                else
                {
                    for (int i = 0; i < rectangles.Count; i++)
                    {
                        if (rectangles[i].Contains(e.Location))
                        {
                            selectedRectangleIndex = i;
                            break;
                        }
                    }
                }
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (isDrawing)
            {
                endPoint = e.Location;
                pictureBox1.Invalidate();
            }
            else if (isSelecting && selectedRectangleIndex != -1)
            {
                int width = rectangles[selectedRectangleIndex].Width;
                int height = rectangles[selectedRectangleIndex].Height;
                int x = e.X - startPoint.X + rectangles[selectedRectangleIndex].X;
                int y = e.Y - startPoint.Y + rectangles[selectedRectangleIndex].Y;
                rectangles[selectedRectangleIndex] = new Rectangle(x, y, width, height);
                pictureBox1.Invalidate();
            }
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                if (isDrawing)
                {
                    endPoint = e.Location;
                    isDrawing = false;
                    rectangles.Add(new Rectangle(Math.Min(startPoint.X, endPoint.X), Math.Min(startPoint.Y, endPoint.Y), Math.Abs(startPoint.X - endPoint.X), Math.Abs(startPoint.Y - endPoint.Y)));
                    dataGridView1.Rows.Add(new object[] { rectangles[rectangles.Count - 1].ToString() });
                    pictureBox1.Invalidate();
                }
                else if (isSelecting)
                {
                    selectedRectangleIndex = -1;
                }
            }
        }

        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            foreach (Rectangle rectangle in rectangles)
            {
                if (rectangle == rectangles[selectedRectangleIndex])
                {
                    e.Graphics.DrawRectangle(Pens.Red, rectangle);
                }
                else
                {
                    e.Graphics.DrawRectangle(Pens.Black, rectangle);
                }
            }
            if (isDrawing)
            {
                e.Graphics.DrawRectangle(Pens.Blue, Math.Min(startPoint.X, endPoint.X), Math.Min(startPoint.Y, endPoint.Y), Math.Abs(startPoint.X - endPoint.X), Math.Abs(startPoint.Y - endPoint.Y));
            }
        }

        private void DataGridView1_SelectionChanged(object sender, EventArgs e)
        {
            if (dataGridView1.SelectedRows.Count > 0)
            {
                selectedRectangleIndex = dataGridView1.SelectedRows[0].Index;
                pictureBox1.Invalidate();
            }
        }

        private void DataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
        {
            string rectangleString = dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].Value.ToString();
            Rectangle rectangle = Rectangle.FromLTRB(int.Parse(rectangleString.Split(',')[0]), int.Parse(rectangleString.Split(',')[1]), int.Parse(rectangleString.Split(',')[2]), int.Parse(rectangleString.Split(',')[3]));
            rectangles[e.RowIndex] = rectangle;
            pictureBox1.Invalidate();
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            SaveFileDialog dialog = new SaveFileDialog();
            dialog.Filter = "Rectangles File (*.rect)|*.rect";
            if (dialog.ShowDialog() == DialogResult.OK)
            {
                using (FileStream fileStream = new FileStream(dialog.FileName, FileMode.Create))
                {
                    BinaryFormatter formatter = new BinaryFormatter();
                    formatter.Serialize(fileStream, rectangles);
                }
            }
        }

        private void btnLoad_Click(object sender, EventArgs e)
        {
            OpenFileDialog dialog = new OpenFileDialog();
            dialog.Filter = "Rectangles File (*.rect)|*.rect";
            if (dialog.ShowDialog() == DialogResult.OK)
            {
                using (FileStream fileStream = new FileStream(dialog.FileName, FileMode.Open))
                {
                    BinaryFormatter formatter = new BinaryFormatter();
                    rectangles = (List<Rectangle>)formatter.Deserialize(fileStream);
                }
                dataGridView1.Rows.Clear();
                foreach (Rectangle rectangle in rectangles)
                {
                    dataGridView1.Rows.Add(new object[] { rectangle.ToString() });
                }
                pictureBox1.Invalidate();
            }
        }
    }
}

在窗体设计器中添加一个PictureBox控件和一个DataGridView控件，并将pictureBox1的MouseDown、MouseMove、MouseUp和Paint事件分别绑定到pictureBox1_MouseDown、pictureBox1_MouseMove、pictureBox1_MouseUp和pictureBox1_Paint方法。将dataGridView1的SelectionChanged和CellEndEdit事件分别绑定到DataGridView1_SelectionChanged和DataGridView1_CellEndEdit方法。添加一个名为btnSave的Button控件和一个名为btnLoad的Button控件，并将它们的Click事件分别绑定到btnSave_Click和btnLoad_Click方法。

在以上示例中，我们使用了一个名为rectangles的List<Rectangle>集合来保存所有绘制的矩形。在pictureBox1的MouseDown、MouseMove和MouseUp事件中，我们分别实现了绘制矩形和选中矩形并拖动和改变大小的功能。在dataGridView1的SelectionChanged事件中，我们实现了选中一行时将对应的矩形设置为选中状态的功能。在dataGridView1的CellEndEdit事件中，我们实现了更新矩形集合中对应的矩形的坐标和大小的功能。在btnSave_Click和btnLoad_Click事件中，我们使用序列化和反序列化来保存和加载矩形集合。