Form1.cs

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

namespace Spencers_QR_Code_Generator
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            comboBoxECC.SelectedIndex = 3;
        }

        private void btnGenerate_Click(object sender, EventArgs e)
        {
            RenderQrCode();
        }


        private void RenderQrCode()
        {
            string level = comboBoxECC.SelectedItem.ToString();
            QRCodeGenerator.ECCLevel eccLevel = (QRCodeGenerator.ECCLevel)(level == "L" ? 0 : level == "M" ? 1 : level == "Q" ? 2 : 3);
            using (QRCodeGenerator qrGenerator = new QRCodeGenerator())
            {
                using (QRCodeData qrCodeData = qrGenerator.CreateQrCode(textBoxQRCode.Text, eccLevel))
                {
                    using (QRCode qrCode = new QRCode(qrCodeData))
                    {

                        pictureBoxQRCode.Image = qrCode.GetGraphic(20, Color.Black, Color.White,
                            GetIconBitmap(), (int)iconSize.Value);

                        //this.pictureBoxQRCode.Size = new System.Drawing.Size(pictureBoxQRCode.Width, pictureBoxQRCode.Height);
                        //Set the SizeMode to center the image.
                        //this.pictureBoxQRCode.SizeMode = PictureBoxSizeMode.CenterImage;

                        pictureBoxQRCode.SizeMode = PictureBoxSizeMode.Zoom;
                    }
                }
            }
        }


        private Bitmap GetIconBitmap()
        {
            Bitmap img = null;
            if (iconPath.Text.Length > 0)
            {
                try
                {
                    img = new Bitmap(iconPath.Text);
                }
                catch (Exception)
                {
                }
            }
            return img;
        }

        private void selectIconBtn_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDlg = new OpenFileDialog();
            openFileDlg.Title = "Select icon";
            openFileDlg.FileName = "";
            openFileDlg.Multiselect = false;
            openFileDlg.CheckFileExists = true;
            if (openFileDlg.ShowDialog() == System.Windows.Forms.DialogResult.OK && openFileDlg.FileName.Length > 0)
            {
                iconPath.Text = openFileDlg.FileName;
                if (iconSize.Value == 0)
                {
                    iconSize.Value = 15;
                }
            }
            else
            {
                iconPath.Text = "";
            }
            RenderQrCode();
        }

        private void buttonSave_Click(object sender, EventArgs e)
        {

            // Displays a SaveFileDialog so the user can save the Image
            SaveFileDialog saveFileDialog1 = new SaveFileDialog();
            saveFileDialog1.Filter = "Bitmap Image|*.bmp|PNG Image|*.png|JPeg Image|*.jpg|Gif Image|*.gif";
            saveFileDialog1.Title = "Save an Image File";
            saveFileDialog1.ShowDialog();

            // If the file name is not an empty string open it for saving.
            if (saveFileDialog1.FileName != "")
            {
                // Saves the Image via a FileStream created by the OpenFile method.
                using (FileStream fs = (System.IO.FileStream)saveFileDialog1.OpenFile())
                {
                    // Saves the Image in the appropriate ImageFormat based upon the
                    // File type selected in the dialog box.
                    // NOTE that the FilterIndex property is one-based.

                    ImageFormat imageFormat = null;
                    switch (saveFileDialog1.FilterIndex)
                    {
                        case 1:
                            imageFormat = ImageFormat.Bmp;
                            break;
                        case 2:
                            imageFormat = ImageFormat.Png;
                            break;
                        case 3:
                            imageFormat = ImageFormat.Jpeg;
                            break;
                        case 4:
                            imageFormat = ImageFormat.Gif;
                            break;
                        default:
                            throw new NotSupportedException("File extension is not supported");
                    }

                    pictureBoxQRCode.Image.Save(fs, imageFormat);
                    fs.Close();
                }
            }
        }

        private void textBoxQRCode_TextChanged(object sender, EventArgs e)
        {
            RenderQrCode();
        }

        private void comboBoxECC_SelectedIndexChanged(object sender, EventArgs e)
        {
            RenderQrCode();
        }

        private void iconSize_ValueChanged(object sender, EventArgs e)
        {
            RenderQrCode();
        }
    }
}