How do I make location and size of button change with picture box size

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace ImageScale
{
    public partial class Form1 : Form
    {
        public Form1() {
            InitializeComponent();
            this.StartPosition = FormStartPosition.CenterScreen;
            this.pictureBox1.BorderStyle = BorderStyle.FixedSingle;
            this.pictureBox1.BackColor = Color.DarkGray;
            this.pictureBox1.MouseWheel += new MouseEventHandler(pictureBox1_MouseWheel);
          
        }

        Bitmap m_bmp;             
        Point m_ptCanvas;          
        Point m_ptCanvasBuf;        
        Point m_ptBmp;              
        float m_nScale = 1.0F;     

        Point m_ptMouseDown;        

        string m_strMousePt;        

        private void Form1_Load(object sender, EventArgs e) {
         
            m_bmp = Properties.Resources.QQ20170722225306;
           
            m_ptCanvas = new Point(pictureBox1.Width / 2, pictureBox1.Height / 2);
            m_ptBmp = new Point(-(m_bmp.Width / 2), -(m_bmp.Height / 2));
           
        }
       
       
        }
        
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

        }
        private void pictureBox1_Paint(object sender, PaintEventArgs e) {
            Graphics g = e.Graphics;
            g.TranslateTransform(m_ptCanvas.X, m_ptCanvas.Y);      
            g.ScaleTransform(m_nScale, m_nScale);                   
            g.DrawImage(m_bmp, m_ptBmp);                          
           
            g.ResetTransform();                                     

        }

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e) {
            if (e.Button == MouseButtons.Middle) {     
                m_ptMouseDown = e.Location;
                m_ptCanvasBuf = m_ptCanvas;
            }
            pictureBox1.Focus();
        }
     
        private void pictureBox1_MouseMove(object sender, MouseEventArgs e) {
            if (e.Button == MouseButtons.Middle) {     
              
                m_ptCanvas = (Point)((Size)m_ptCanvasBuf + ((Size)e.Location - (Size)m_ptMouseDown));
                pictureBox1.Invalidate();
            }
           
        }
       
        private void pictureBox1_MouseWheel(object sender, MouseEventArgs e) {
            if (m_nScale <= 0.3 && e.Delta <= 0) return;       
            if (m_nScale >= 4.9 && e.Delta >= 0) return;       
          
            SizeF szSub = (Size)m_ptCanvas - (Size)e.Location;
            
            float tempX = szSub.Width / m_nScale;          
            float tempY = szSub.Height / m_nScale;         
          
            m_ptCanvas.X -= (int)(szSub.Width - tempX);     
            m_ptCanvas.Y -= (int)(szSub.Height - tempY);    
                               
            szSub.Width = tempX;
            szSub.Height = tempY;
            m_nScale += e.Delta > 0 ? 0.2F : -0.2F;
            m_ptCanvas.X += (int)(szSub.Width * m_nScale - szSub.Width);
            m_ptCanvas.Y += (int)(szSub.Height * m_nScale - szSub.Height);
            pictureBox1.Invalidate();
          
        }