init

.gitignore

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+.idea/
+obj/
+bin/

DemoAndroid.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DemoAndroid", "DemoAndroid\DemoAndroid.csproj", "{2A2871F0-6043-40CD-8249-3B20E56B8EF4}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{2A2871F0-6043-40CD-8249-3B20E56B8EF4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2A2871F0-6043-40CD-8249-3B20E56B8EF4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2A2871F0-6043-40CD-8249-3B20E56B8EF4}.Debug|Any CPU.Deploy.0 = Debug|Any CPU
+		{2A2871F0-6043-40CD-8249-3B20E56B8EF4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2A2871F0-6043-40CD-8249-3B20E56B8EF4}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2A2871F0-6043-40CD-8249-3B20E56B8EF4}.Release|Any CPU.Deploy.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

DemoAndroid/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+  <application android:allowBackup="true" android:icon="@mipmap/appicon" android:label="@string/app_name" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true">
+  </application>
+  <uses-permission android:name="android.permission.INTERNET" />
+</manifest>

DemoAndroid/DemoAndroid.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+        <TargetFramework>net8.0-android</TargetFramework>
+        <SupportedOSPlatformVersion>21</SupportedOSPlatformVersion>
+        <OutputType>Exe</OutputType>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <ApplicationId>com.maurict.androiddemo</ApplicationId>
+        <ApplicationVersion>1</ApplicationVersion>
+        <ApplicationDisplayVersion>1.0</ApplicationDisplayVersion>
+        
+        <!-- With AOT, our app is crashing in Release mode -->
+        <AotAssemblies>False</AotAssemblies>
+    </PropertyGroup>
+    <ItemGroup>
+      <PackageReference Include="QRCoder-ImageSharp" Version="0.10.0" />
+    </ItemGroup>
+</Project>

DemoAndroid/MainActivity.cs

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+using Android.Graphics;
+using QRCoder;
+using Exception = Java.Lang.Exception; // QRCoder-ImageSharp else it crashes
+
+namespace DemoAndroid;
+
+[Activity(Label = "@string/app_name", MainLauncher = true)]
+public class MainActivity : Activity
+{
+    private string _text = "";
+    private ImageView? _ivQr;
+    
+    protected override void OnCreate(Bundle? savedInstanceState)
+    {
+        base.OnCreate(savedInstanceState);
+
+        // Set our view from the "main" layout resource
+        SetContentView(Resource.Layout.activity_main);
+
+        var etInput = FindViewById<EditText>(Resource.Id.etInput) ?? throw new Exception("EditText #etInput not found");
+        _ivQr = FindViewById<ImageView>(Resource.Id.ivQR) ?? throw new Exception("ImageView #ivQR not found");;
+
+        etInput.TextChanged += (sender, args) =>
+        {
+            _text = args.Text?.ToString() ?? string.Empty;
+        
+            if (!string.IsNullOrEmpty(_text))
+            {
+                CreateQr();
+            }
+        };
+    }
+
+    private void CreateQr()
+    {
+        using var qrGenerator = new QRCodeGenerator();
+        using var qrCodeData = qrGenerator.CreateQrCode(_text, QRCodeGenerator.ECCLevel.Q);
+        using var qrCode = new PngByteQRCode(qrCodeData);
+        
+        var qrCodeImage = qrCode.GetGraphic(20);
+        var javaBitmap = BitmapFactory.DecodeByteArray(qrCodeImage, 0, qrCodeImage.Length);
+        _ivQr?.SetImageBitmap(javaBitmap);
+    }
+}

DemoAndroid/Resources/AboutResources.txt

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+Images, layout descriptions, binary blobs and string dictionaries can be included 
+in your application as resource files.  Various Android APIs are designed to 
+operate on the resource IDs instead of dealing with images, strings or binary blobs 
+directly.
+
+For example, a sample Android app that contains a user interface layout (main.xml),
+an internationalization string table (strings.xml) and some icons (drawable-XXX/icon.png) 
+would keep its resources in the "Resources" directory of the application:
+
+Resources/
+    drawable/
+        icon.png
+
+    layout/
+        main.xml
+
+    values/
+        strings.xml
+
+In order to get the build system to recognize Android resources, set the build action to
+"AndroidResource".  The native Android APIs do not operate directly with filenames, but 
+instead operate on resource IDs.  When you compile an Android application that uses resources, 
+the build system will package the resources for distribution and generate a class called "Resource" 
+(this is an Android convention) that contains the tokens for each one of the resources 
+included. For example, for the above Resources layout, this is what the Resource class would expose:
+
+public class Resource {
+    public class Drawable {
+        public const int icon = 0x123;
+    }
+
+    public class Layout {
+        public const int main = 0x456;
+    }
+
+    public class Strings {
+        public const int first_string = 0xabc;
+        public const int second_string = 0xbcd;
+    }
+}
+
+You would then use Resource.Drawable.icon to reference the drawable/icon.png file, or 
+Resource.Layout.main to reference the layout/main.xml file, or Resource.Strings.first_string 
+to reference the first string in the dictionary file values/strings.xml.

DemoAndroid/Resources/layout/activity_main.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:orientation="vertical">
+    
+    <EditText android:id="@+id/etInput"
+              android:layout_width="match_parent" 
+              android:layout_height="wrap_content"
+              android:hint="Enter text here to create QR"/>
+    
+    <ImageView android:id="@+id/ivQR"
+            android:layout_width="match_parent" 
+               android:layout_height="wrap_content" />
+</LinearLayout>

DemoAndroid/Resources/mipmap-anydpi-v26/appicon.xml

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+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <background android:drawable="@mipmap/appicon_background" />
+  <foreground android:drawable="@mipmap/appicon_foreground" />
+</adaptive-icon>

DemoAndroid/Resources/mipmap-anydpi-v26/appicon_round.xml

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+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <background android:drawable="@mipmap/appicon_background" />
+  <foreground android:drawable="@mipmap/appicon_foreground" />
+</adaptive-icon>

DemoAndroid/Resources/values/colors.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="blue">#4287f5</color>
+    <color name="white">#FFFFFF</color>
+</resources>

DemoAndroid/Resources/values/ic_launcher_background.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#2C3E50</color>
+</resources>

DemoAndroid/Resources/values/strings.xml

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+<resources>
+    <string name="app_name">DemoAndroid</string>
+    <string name="app_text">Hello, Android!</string>
+</resources>