Added intent filter for open with

Added functionality to read the file from Intent data

Author: jonvwolf

BasicPlainTextReaderApp/BasicPlainTextReaderApp.Android/MainActivity.cs

@@ -2,26 +2,67 @@
 
 using Android.App;
 using Android.Content.PM;
+using Android.Content;
 using Android.Runtime;
 using Android.Views;
 using Android.Widget;
 using Android.OS;
+using System.IO;
+using Android.Provider;
+using System.Text;
 
 namespace BasicPlainTextReaderApp.Droid
 {
-    [Activity(Label = "Basic Plain Text Reader", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize )]
+    [Activity(Label = "Basic Plain Text Reader", 
+        Icon = "@mipmap/icon", 
+        Theme = "@style/MainTheme", 
+        MainLauncher = true, 
+        ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize)]
+    [IntentFilter(new[] { Intent.ActionView }, Categories = new[] { Intent.CategoryDefault }, DataMimeType = @"*/*")]
     public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
     {
         protected override void OnCreate(Bundle savedInstanceState)
         {
+            string action = Intent.Action;
+            string type = Intent.Type;
+            StringBuilder sb = null;
+
+            if(Intent.ActionView.Equals(action) && !string.IsNullOrEmpty(type))
+            {
+                Android.Net.Uri fileUri = Intent.Data;
+                if (fileUri != null)
+                {
+                    try
+                    {
+                        using (var parcelFileDescriptor = ContentResolver.OpenFileDescriptor(Intent.Data, "r"))
+                        using (Java.IO.FileDescriptor fileDescriptor = parcelFileDescriptor.FileDescriptor)
+                        using (var reader = new Java.IO.FileReader(fileDescriptor))
+                        using (var bufferedReader = new Java.IO.BufferedReader(reader))
+                        {
+                            string line;
+                            sb = new StringBuilder();
+                            while ((line = bufferedReader.ReadLine()) != null)
+                            {
+                                sb.AppendLine(line);
+                            }
+                        }
+                    }
+                    catch (Exception e)
+                    {
+                        sb = new StringBuilder();
+                        sb.AppendLine(e.ToString());
+                    }
+                }
+            }
+
             TabLayoutResource = Resource.Layout.Tabbar;
             ToolbarResource = Resource.Layout.Toolbar;
 
             base.OnCreate(savedInstanceState);
 
             Xamarin.Essentials.Platform.Init(this, savedInstanceState);
             global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
-            LoadApplication(new App());
+            LoadApplication(new App(sb.ToString()));
         }
         public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
         {

BasicPlainTextReaderApp/BasicPlainTextReaderApp.Android/Properties/AndroidManifest.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="dev.jonwolf.basicplaintextreaderapp" android:installLocation="auto">
 	<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="28" />
+	<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
 	<application android:label="Basic Plain Text Reader" android:theme="@style/MainTheme"></application>
 </manifest>

BasicPlainTextReaderApp/BasicPlainTextReaderApp/App.xaml.cs

@@ -7,11 +7,12 @@ namespace BasicPlainTextReaderApp
 {
     public partial class App : Application
     {
-
-        public App()
+        string _text;
+        public App(string text = null)
         {
             InitializeComponent();
 
+            _text = text;
             MainPage = new AppShell();
         }