Add file picker

Author: daniel-lerch

src/Vocup.Android/App.cs

@@ -10,4 +10,9 @@ public App(MainActivity mainActivity)
     {
         this.mainActivity = mainActivity;
     }
+
+    protected override void BrowseFile()
+    {
+        mainActivity?.ShowFilePicker();
+    }
 }

src/Vocup.Android/MainActivity.cs

@@ -2,6 +2,7 @@
 using Android.Content;
 using Android.Content.PM;
 using Android.OS;
+using Android.Runtime;
 using Android.Util;
 using Avalonia;
 using Avalonia.Android;
@@ -25,6 +26,7 @@ namespace Vocup.Android;
 public class MainActivity : AvaloniaMainActivity<App>
 {
     private const string Tag = "Vocup.Android.MainActivity";
+    private const int FilePickerRequestCode = 3147;
 
     protected override AppBuilder CreateAppBuilder()
     {
@@ -50,6 +52,38 @@ protected override void OnNewIntent(Intent? intent)
         HandleIntent(intent);
     }
 
+    public void ShowFilePicker()
+    {
+        var intent = new Intent(Intent.ActionGetContent);
+        intent.SetType("application/octet-stream");
+        intent.AddCategory(Intent.CategoryOpenable);
+        intent.AddFlags(ActivityFlags.GrantReadUriPermission);
+        StartActivityForResult(Intent.CreateChooser(intent, "Select a file"), FilePickerRequestCode);
+    }
+
+    protected override void OnActivityResult(int requestCode, [GeneratedEnum] Result resultCode, Intent? data)
+    {
+        base.OnActivityResult(requestCode, resultCode, data);
+
+        if (requestCode == FilePickerRequestCode && resultCode == Result.Ok && data?.Data != null)
+        {
+            using System.IO.Stream? stream = ContentResolver?.OpenInputStream(data.Data);
+            
+            if (stream == null)
+            {
+                Log.Error(Tag, "Stream is null in OnActivityResult");
+                return;
+            }
+            if (Avalonia.Application.Current is not App app)
+            {
+                Log.Error(Tag, "App is null in OnActivityResult");
+                return;
+            }
+            Log.Debug(Tag, $"File size is {stream.Length} bytes");
+            app.OpenFile(stream);
+        }
+    }
+
     private void HandleIntent(Intent? intent)
     {
         if (intent?.Action == Intent.ActionView && intent.Data != null)

src/Vocup/App.axaml.cs

@@ -1,6 +1,7 @@
 using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
+using ReactiveUI;
 using System.IO;
 using Vocup.ViewModels;
 using Vocup.Views;
@@ -26,21 +27,31 @@ public void OpenFile(Stream input)
 
     public override void OnFrameworkInitializationCompleted()
     {
+        mainViewModel = new MainViewModel
+        {
+            OpenFileCommand = ReactiveCommand.Create(BrowseFile)
+        };
+
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
             desktop.MainWindow = new MainWindow
             {
-                DataContext = mainViewModel = new MainViewModel()
+                DataContext = mainViewModel
             };
         }
         else if (ApplicationLifetime is ISingleViewApplicationLifetime singleViewPlatform)
         {
             singleViewPlatform.MainView = new MainView
             {
-                DataContext = mainViewModel = new MainViewModel()
+                DataContext = mainViewModel
             };
         }
 
         base.OnFrameworkInitializationCompleted();
     }
+
+    protected virtual void BrowseFile()
+    {
+
+    }
 }

src/Vocup/ViewModels/MainViewModel.cs

@@ -1,4 +1,5 @@
 using ReactiveUI;
+using System.Windows.Input;
 
 namespace Vocup.ViewModels;
 
@@ -12,4 +13,6 @@ public long FileLength
     }
 
     public AboutViewModel About { get; } = new();
+
+    public required ICommand OpenFileCommand { get; init; }
 }

src/Vocup/Views/MainView.axaml

@@ -15,6 +15,7 @@
 
   <StackPanel>
     <TextBlock Text="{Binding FileLength}" />
+    <Button Command="{Binding OpenFileCommand}" Content="Open File" />
     <views:AboutView DataContext="{Binding About}" />
   </StackPanel>