Windows Forms: How to zoom an image in C#

Step 1: Click New Project, then select Visual C# on the left, then Windows and then select Windows Forms Application. Name your project "ImageZoom" and then click OK

Step 2: Design your form as below

Step 3: Add code to button click event handler as below

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

namespace ImageZoom
{
    public partial class Form1 : Form
    {
        Image imgOriginal;

        public Form1()
        {
            InitializeComponent();
        }

        private void btnOpen_Click(object sender, EventArgs e)
        {
            //Open image
            using (OpenFileDialog ofd = new OpenFileDialog() { Multiselect = false, ValidateNames = true, Filter = "JPEG|*.jpg" })
            {
                if (ofd.ShowDialog() == DialogResult.OK)
                {
                    pictureBox1.Image = Image.FromFile(ofd.FileName);
                    imgOriginal = pictureBox1.Image;
                }
            }
        }

        //Zoom image file
        Image Zoom(Image img,Size size)
        {
            Bitmap bmp = new Bitmap(img, img.Width + (img.Width * size.Width / 100), img.Height + (img.Height * size.Height / 100));
            Graphics g = Graphics.FromImage(bmp);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            return bmp;
        }

        private void trackBar1_Scroll(object sender, EventArgs e)
        {
            if (trackBar1.Value > 0)
            {
                pictureBox1.Image = Zoom(imgOriginal, new Size(trackBar1.Value, trackBar1.Value));
            }
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (pictureBox1.Image != null)
                pictureBox1.Dispose();
        }
    }
}

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