Introduction

Here, I am going to discuss how to generate Barcodes or QR codes in Xamarin for Android. In order to do this, we need to get some information from the user, such as what message they want to convert, the code format they want to use, and their desired bitmap size. There is no default library for this, so we need to install a plugin.

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Just write a few lines of code to generate 1D and 2D code. Barcodes have different formats, but I will demonstrate only a few code formats — Code 39, Code 128, AZTEC, and QR Code. Below is our final output for the project, so you can visualize our end-result throughout the tutorial. 

Let’s start.
 

Step One

Create a Xamarin.Android application by going to Visual Studio >> New Project >> Android App. Once there, click Next.

Here, let's provide a project name, organization name, app compatibility, and app theme. Then, click Create. 

Step Two

After project creation, we need to install a plugin. For this, go to Solution Explorer, right-click Packages, and select Add packages. A new window will appear; at the top-right, search for "ZXing.Net plugin," and add the package.

Step Three

Now, let’s code. First, open  content_main.xml. For that, go to Solution Explorer >> Resource >> Layout and double-click to open  content_main.xml. Add the following code to this file.

<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout  
    xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:app="http://schemas.android.com/apk/res-auto"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    app:layout_behavior="@string/appbar_scrolling_view_behavior"  
    tools:showIn="@layout/activity_main">  
    <TextView  
        android:id="@+id/txtChooseStatic"  
       android:layout_width="fill_parent"    
       android:layout_height="wrap_content"    
       android:layout_marginTop="10dp"  
       android:layout_alignParentTop="true"  
       android:text="Choose Encoding Method" />    
    <Spinner    
       android:id="@+id/spinner"    
       android:layout_width="fill_parent"  
        android:layout_marginTop="10dp"  
        android:layout_height="wrap_content"  
       android:layout_below="@+id/txtChooseStatic"  
       android:prompt="@string/action_choose"/>  
    <EditText  
         android:id="@+id/plain_text_input"  
         android:layout_height="wrap_content"  
         android:layout_width="match_parent"  
         android:layout_margin="10dp"  
         android:layout_below="@+id/spinner"  
         android:hint="Type Message to Convert"  
         android:inputType="text"/>  
    <ImageView  
        android:layout_centerHorizontal="true"  
        android:layout_marginTop="10dp"  
        android:id="@+id/barcodeImage"  
        android:layout_below="@+id/plain_text_input"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"/>  
    <Button  
        android:id="@+id/generate"  
        android:background="#000000"  
        android:textColor="#ffffff"  
        android:layout_centerHorizontal="true"  
        android:layout_width="wrap_content"  
        android:padding="10dp"  
        android:layout_marginTop="10dp"  
        android:layout_below="@+id/barcodeImage"  
        android:layout_height="wrap_content"  
        android:textSize="15dp"  
        android:text="Generate Code"/>  

</RelativeLayout>  

Step Four

Next, open MainActivity.cs and add the following code to generate the barcode.

using System;  
using System.IO;  
using Android.App;  
using Android.Content.PM;  
using Android.Graphics;  
using Android.OS;  
using Android.Runtime;  
using Android.Support.Design.Widget;  
using Android.Support.V4.App;  
using Android.Support.V4.Content;  
using Android.Support.V7.App;  
using Android.Views;  
using Android.Widget;  
using ZXing;  
using ZXing.Common;  

namespace BarCodeGenerator  
{  
    [Activity(Label = "@string/app_name", Theme = "@style/AppTheme.NoActionBar", MainLauncher = true)]  
    public class MainActivity : AppCompatActivity  
    {  
        private TextView txtMessage;  
        private string message;  
        private static int size = 660;  
        private static int small_size = 264;  
        private Spinner spinnerValue;  
        private string CodeType;  

        protected override void OnCreate(Bundle savedInstanceState)  
        {  
            base.OnCreate(savedInstanceState);  
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);  
            SetContentView(Resource.Layout.activity_main);  

            Android.Support.V7.Widget.Toolbar toolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);  
            SetSupportActionBar(toolbar);  

            ImageView image = FindViewById<ImageView>(Resource.Id.barcodeImage);  
            Button btnGenerate = FindViewById<Button>(Resource.Id.generate);  
            txtMessage = FindViewById<TextView>(Resource.Id.plain_text_input);  
            spinnerValue = FindViewById<Spinner>(Resource.Id.spinner);  
            FloatingActionButton fab = FindViewById<FloatingActionButton>(Resource.Id.fab);  

            var adapter = ArrayAdapter.CreateFromResource(this, Resource.Array.selected_Code, Android.Resource.Layout.SimpleSpinnerItem);  
            adapter.SetDropDownViewResource(Android.Resource.Layout.SimpleSpinnerDropDownItem);  
            spinnerValue.Adapter = adapter;  
            spinnerValue.ItemSelected += new EventHandler<AdapterView.ItemSelectedEventArgs>(SpinnerItemSelect);  
            fab.Click += FabOnClick;  

            btnGenerate.Click += delegate  
            {  
                string[] PERMISSIONS =  
                {  
                    "android.permission.READ_EXTERNAL_STORAGE",  
                    "android.permission.WRITE_EXTERNAL_STORAGE"  
                };  

                var permission = ContextCompat.CheckSelfPermission(this, "android.permission.WRITE_EXTERNAL_STORAGE");  
                var permissionread = ContextCompat.CheckSelfPermission(this, "android.permission.READ_EXTERNAL_STORAGE");  

                if (permission != Permission.Granted && permissionread != Permission.Granted)  
                    ActivityCompat.RequestPermissions(this, PERMISSIONS, 1);  

                try  
                {  
                    if (permission == Permission.Granted && permissionread == Permission.Granted)  
                    {  
                        BitMatrix bitmapMatrix = null;  
                        message = txtMessage.Text.ToString();  

                        switch (CodeType)  
                        {  
                            case "QR Code":  
                                bitmapMatrix = new MultiFormatWriter().encode(message, BarcodeFormat.QR_CODE, size, size);  
                                break;  
                            case "PDF 417":  
                                bitmapMatrix = new MultiFormatWriter().encode(message, BarcodeFormat.PDF_417, size, small_size);  
                                break;  
                            case "CODE 128":  
                                bitmapMatrix = new MultiFormatWriter().encode(message, BarcodeFormat.CODE_128, size, small_size);  
                                break;  
                            case "CODE 39":  
                                bitmapMatrix = new MultiFormatWriter().encode(message, BarcodeFormat.CODE_39, size, small_size);  
                                break;  
                            case "AZTEC":  
                                bitmapMatrix = new MultiFormatWriter().encode(message, BarcodeFormat.AZTEC, size, small_size);  
                                break;  
                        }  

                        var width = bitmapMatrix.Width;  
                        var height = bitmapMatrix.Height;  
                        int[] pixelsImage = new int[width * height];  

                        for (int i = 0; i < height; i++)  
                        {  
                            for (int j = 0; j < width; j++)  
                            {  
                                if (bitmapMatrix[j, i])  
                                    pixelsImage[i * width + j] = (int)Convert.ToInt64(0xff000000);  
                                else  
                                    pixelsImage[i * width + j] = (int)Convert.ToInt64(0xffffffff);  

                            }  
                        }  

                        Bitmap bitmap = Bitmap.CreateBitmap(width, height, Bitmap.Config.Argb8888);  
                        bitmap.SetPixels(pixelsImage, 0, width, 0, 0, width, height);  

                        var sdpath = Android.OS.Environment.ExternalStorageDirectory.AbsolutePath;  
                        var path = System.IO.Path.Combine(sdpath, "logeshbarcode.jpg");  
                        var stream = new FileStream(path, FileMode.Create);  
                        bitmap.Compress(Bitmap.CompressFormat.Jpeg, 100, stream);  
                        stream.Close();  

                        image.SetImageBitmap(bitmap);  
                    }  
                    else  
                    {  
                        Console.WriteLine("No Permission");  
                    }  
                }  
                catch (Exception ex)  
                {  
                    Console.WriteLine($"Exception {ex} ");  
                }  
            };  
        }  

        private void SpinnerItemSelect(object sender, AdapterView.ItemSelectedEventArgs e)  
        {  
            Spinner spinner = (Spinner)sender;  
            CodeType = (string)spinner.GetItemAtPosition(e.Position);  
        }  

        public override bool OnCreateOptionsMenu(IMenu menu)  
        {  
            MenuInflater.Inflate(Resource.Menu.menu_main, menu);  
            return true;  
        }  

        public override bool OnOptionsItemSelected(IMenuItem item)  
        {  
            int id = item.ItemId;  
            if (id == Resource.Id.action_settings)  
            {  
                return true;  
            }  

            return base.OnOptionsItemSelected(item);  
        }  

        private void FabOnClick(object sender, EventArgs eventArgs)  
        {  
            View view = (View)sender;  
            Snackbar.Make(view, "Replace with your own action", Snackbar.LengthLong)  
                .SetAction("Action", (Android.Views.View.IOnClickListener)null).Show();  
        }  
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)  
        {  
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);  

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);  
        }  
    }  
}  

Step Five

Finally, the application requires storage read and write permissions. For that, go to Solution Explorer >> Properties >> AndroidManifest.xml file. Check the permissions for External Storage Read and Write.

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />  
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Step Six

Now, press F5 to run the application. The output will look like this: 

You can get the full source code here. 

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