How to create barcodes in C# WPF Windows application

using BarcodeLib.Barcode;
using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace BarcodeLib.Create.WPFCoreDemo
{

    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public const int Preview_Width = 400;

        public MainWindow()
        {
            InitializeComponent();

            //  Initial TextBox
            this.tbData.Text = "QR Code";
            this.tbBarcodeWidth.Text = "2";     //  2 inches
            this.tbResolution.Text = "300";     //  300 dots per inch
            this.tbForeColor.Text = "000000";   //  Black
            this.tbBackColor.Text = "FFFFFF";   //  White

            //  Show preview barcode image.
            updatePreviewImage();
        }

        private void tbBarcodeWidth_PreviewTextInput(object sender, TextCompositionEventArgs e)
        {   //  Barcode Width must be a float value
            e.Handled = !isValidChars(e.Text, "0123456789.");
        }
        private void tbResolution_PreviewTextInput(object sender, TextCompositionEventArgs e)
        {   //  Resolution must be an int value
            e.Handled = !isValidChars(e.Text, "0123456789");
        }
        private void tbColor_PreviewTextInput(object sender, TextCompositionEventArgs e)
        {   //  Fore Color and Back Color must be a Hex char string
            e.Handled = !isValidChars(e.Text, "0123456789ABCDEFabcdef");
        }
        private bool isValidChars(String content, String validCharSet)
        {
            foreach (char c in content)
            {
                if (!validCharSet.Contains(c))
                    return false;
            }
            return true;
        }

        private void tbBarcodeWidth_TextChanged(object sender, TextChangedEventArgs e)
        {
            float result;
            bool isValid = float.TryParse(tbBarcodeWidth.Text, out result);
            if (isValid) isValid = result > 0;
            updateTextBoxBackground(this.tbBarcodeWidth, isValid);
        }
        private void tbResolution_TextChanged(object sender, TextChangedEventArgs e)
        {
            int result;
            bool isValid = int.TryParse(tbBarcodeWidth.Text, out result);
            if (isValid) isValid = result > 0;
            updateTextBoxBackground(this.tbBarcodeWidth, isValid);
        }
        //  Set background color of the TextBox to Red if the Text is invalid.
        private void updateTextBoxBackground(TextBox tb, bool isValid)
        {
            System.Windows.Media.Color normal = System.Windows.Media.Color.FromRgb(255, 255, 255);
            System.Windows.Media.Color error = System.Windows.Media.Color.FromRgb(255, 0, 0);
            tb.Background = new SolidColorBrush(isValid ? normal : error);
        }

        private void tbForeColor_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (this.rectForeColor == null)
                return;

            try
            {
                System.Drawing.Color color = parseColorString(this.tbForeColor.Text);
                //  Not transparent
                if (color != System.Drawing.Color.Transparent)
                {
                    System.Windows.Media.Color mColor = System.Windows.Media.Color.FromRgb(color.R, color.G, color.B);
                    this.rectForeColor.Fill = new System.Windows.Media.SolidColorBrush(mColor);
                    this.rectForeColor.Visibility = Visibility.Visible;
                }
                //  Hidden Rectangle if set to transparent.
                else
                    this.rectForeColor.Visibility = Visibility.Hidden;
            }
            catch (Exception)
            {
                this.rectForeColor.Visibility = Visibility.Hidden;
            }

            int len = this.tbForeColor.Text.Length;
            bool isValid = len == 6;
            updateTextBoxBackground(this.tbForeColor, isValid);
        }
        private void tbBackColor_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (this.rectBackColor == null)
                return;

            try
            {
                System.Drawing.Color color = parseColorString(this.tbBackColor.Text);
                //  Not transparent
                if (color != System.Drawing.Color.Transparent)
                {
                    System.Windows.Media.Color mColor = System.Windows.Media.Color.FromRgb(color.R, color.G, color.B);
                    this.rectBackColor.Fill = new System.Windows.Media.SolidColorBrush(mColor);
                    this.rectBackColor.Visibility = Visibility.Visible;
                }
                //  Hidden Rectangle if set to transparent.
                else
                    this.rectBackColor.Visibility = Visibility.Hidden;
            }
            catch (Exception)
            {
                this.rectBackColor.Visibility = Visibility.Hidden;
            }

            int len = this.tbBackColor.Text.Length;
            bool isValid = len == 0 || len == 6;
            updateTextBoxBackground(this.tbBackColor, isValid);
        }
        //  Parse Color string to System.Drawing.Color
        private System.Drawing.Color parseColorString(String rrggbb)
        {
            //  Input must be a string with 6 hex chars.
            if (rrggbb == null || rrggbb.Length != 6)
                return System.Drawing.Color.Transparent;

            try
            {
                int r = hexCharToInt(rrggbb[0]) * 16 + hexCharToInt(rrggbb[1]);
                int g = hexCharToInt(rrggbb[2]) * 16 + hexCharToInt(rrggbb[3]);
                int b = hexCharToInt(rrggbb[4]) * 16 + hexCharToInt(rrggbb[5]);
                return System.Drawing.Color.FromArgb(r, g, b);
            }
            catch (Exception)
            {
                return System.Drawing.Color.Transparent;
            }
        }
        //  Convert Hex Char to integer.
        //  Valid Input: '0' ~ '9', 'A' ~ 'F' or 'a' ~ 'f'.
        //  Throw exception if input is invalid.
        private int hexCharToInt(char c)
        {
            if (c >= '0' && c <= '9')
                return (int)c - (int)'0';
            if (c >= 'A' && c <= 'F')
                return (int)c - (int)'A' + 10;
            if (c >= 'a' && c <= 'f')
                return (int)c - (int)'a' + 10;
            throw new Exception("Invalid Hex. Char");
        }

        private void btReview_Click(object sender, RoutedEventArgs e)
        {
            updatePreviewImage();
        }
        private void updatePreviewImage()
        {
            try
            {
                QRCode qrcode = generateBarcodeObject();
                
                Bitmap bitmap = qrcode.drawBarcode();
                //  Resize barcode image to preview image.
                Bitmap previewImg = new Bitmap(Preview_Width, Preview_Width);
                using (Graphics g = Graphics.FromImage(previewImg))
                {
                    g.DrawImage(bitmap, 0, 0, previewImg.Width, previewImg.Height);
                }
                //  Update Image control
                using (MemoryStream ms = new MemoryStream())
                {
                    previewImg.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                    BitmapImage bi = new BitmapImage();
                    bi.BeginInit();
                    bi.StreamSource = ms;
                    bi.CacheOption = BitmapCacheOption.OnLoad;
                    bi.EndInit();
                    this.imgReview.Width = Preview_Width;
                    this.imgReview.Height = Preview_Width;
                    this.imgReview.Source = bi;
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Create preview image failed. " + ex.Message);
            }
        }
        private QRCode generateBarcodeObject()
        {
            String data = this.tbData.Text;
            float imgWidthInInch;
            if (float.TryParse(this.tbBarcodeWidth.Text, out imgWidthInInch) == false)
                throw new Exception("Invalid Barcode Width");
            int dpi;
            if (int.TryParse(this.tbResolution.Text, out dpi) == false)
                throw new Exception("Invalid Resolution");
            if (this.tbForeColor.Text.Length != 6)
                throw new Exception("Invalid Fore Color");
            if (this.tbBackColor.Text.Length != 6
                && this.tbBackColor.Text.Length != 0)
                throw new Exception("Invalid Back Color");

            System.Drawing.Color foreColor = parseColorString(this.tbForeColor.Text);
            System.Drawing.Color backColor = parseColorString(this.tbBackColor.Text);
            QRCode barcode = new QRCode();
            barcode.Encoding = QRCodeEncoding.Auto;
            barcode.Version = QRCodeVersion.V1;
            barcode.ECL = QRCodeErrorCorrectionLevel.L;


            // Use Auto Size mode
            barcode.ResizeImage = true;
            // Set padding area to transparent
            barcode.ResizeImagePaddingTransparent = true;
            barcode.Data = data;
            barcode.UOM = UnitOfMeasure.INCH;
            barcode.Resolution = dpi;
            barcode.ImageWidth = imgWidthInInch;
            barcode.ImageHeight = imgWidthInInch;
            barcode.ModuleColor = foreColor;
            barcode.BackgroundColor = backColor;
            barcode.ImageFormat = System.Drawing.Imaging.ImageFormat.Png;
            return barcode;
        }

        private void btSave_Click(object sender, RoutedEventArgs e)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            saveFileDialog.Filter = "PNG Files (*.png)|*.png";
            saveFileDialog.DefaultExt = ".png";
            if (saveFileDialog.ShowDialog() == true)
            {
                String outputFilePath = saveFileDialog.FileName;
                try
                {
                    QRCode qrcode = generateBarcodeObject();
                    qrcode.drawBarcode(outputFilePath);
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Save to file failed. " + ex.Message);
                }
            }
        }
    }
}