Update

BlazorDemo.Web/Pages/Index.razor

@@ -19,7 +19,7 @@
 @code {
     [Inject] private IJSRuntime? _js { get; set; }
 
-    private Action<MemoryStream, string>? _callback;
+    private Action<Stream, string>? _callback;
 
     private InputFile? _inputFile;
 
@@ -40,25 +40,45 @@
             stream.Position = 0;
             _callback?.Invoke(stream, file.Name);
         }
-/*
+
+        /*
         var stream = new MemoryStream();
         var file = e.File;
         await e.File.OpenReadStream().CopyToAsync(stream);
         stream.Position = 0;
         _callback?.Invoke(stream,  file.Name);
-*/
+        */
 
         _callback = null;
     }
 
-    public async Task ShowInputDialog(Action<MemoryStream, string> callback)
+    public class InputDialogOptions
+    {
+        public Action<Stream, string>? Callback { get; set; }
+
+        public string Filter { get; set; } = ".*";
+
+        public bool AllowMultiple { get; set; } = false;
+
+        public bool OpenFolder { get; set; } = false;
+    }
+
+    public async Task ShowInputDialog(Action<Stream, string> callback)
     {
         if (_js is { } && _inputFile is { })
         {
             Console.WriteLine("ShowInputDialog() Begin");
             _callback = callback;
+
+            _filter = ".txt";
+            _allowMultiple = true;
+            _openFolder = false;
+
             await _js.InvokeVoidAsync("ShowInputDialog", "file");
-            //await _js.InvokeVoidAsync("getFile");
+
+            //var stream = await _js.InvokeAsync<FileStream>("ShowOpenFilePicker");
+            //_callback(stream, "test");
+
             Console.WriteLine("ShowInputDialog() End");
         }
     }

BlazorDemo.Web/wwwroot/js/dialogs.js

@@ -1,49 +1,35 @@
 
-// https://stackoverflow.com/questions/4628544/how-to-detect-when-cancel-is-clicked-on-file-input
-
-// https://codepen.io/matuzo/pen/KOdpmq?editors=1111
-// https://caniuse.com/?search=webkitdirectory
 
 async function ShowInputDialog(id) {
     await document.querySelector('input#' + id).click();
 }
 
-
 // https://web.dev/file-system-access/
-// https://www.thinktecture.com/en/pwa/making-of-paint-js-file-access/
-
 
 // https://developer.mozilla.org/en-US/docs/Web/API/Window/showOpenFilePicker
 
-const pickerOpts = {
+async function ShowOpenFilePicker() {
+
+  const opts = {
     types: [
       {
-        description: 'Supported files',
-        accept: {
-          'image/*': ['.png', '.gif', '.jpeg', '.jpg']
-        }
+        description: 'Text file',
+        accept: {'text/plain': ['.txt']},
       },
     ],
     excludeAcceptAllOption: true,
     multiple: false
   };
 
-// create a reference for our file handle
-let fileHandle;
+  const fileHandles = await window.showOpenFilePicker(opts);
+  const file = await fileHandles[0].getFile();
 
-async function getFile() {
-  // open file picker, destructure the one element returned array
-  [fileHandle] = await window.showOpenFilePicker(pickerOpts);
-
-  // run code with our fileHandle
-  
+  return file.stream();
 }
 
-
-
 // https://developer.mozilla.org/en-US/docs/Web/API/window/showSaveFilePicker
 
-function getNewFileHandle() {
+function ShowSaveFilePicker() {
     const opts = {
       types: [{
         description: 'Text file',
@@ -53,5 +39,9 @@ function getNewFileHandle() {
     return window.showSaveFilePicker(opts);
   }
 
+// https://developer.mozilla.org/en-US/docs/Web/API/window/showDirectoryPicker
 
-  // https://developer.mozilla.org/en-US/docs/Web/API/window/showDirectoryPicker
+async function ShowDirectoryPicker() {
+  const dirHandle = await window.showDirectoryPicker();
+  return dirHandle;
+}

BlazorDemo/App.axaml.cs

@@ -11,7 +11,7 @@ namespace BlazorDemo
 {
     public partial class App : Application
     {
-        public static Func<Action<MemoryStream, string>, Task>? ShowInputDialog { get; set;}
+        public static Func<Action<Stream, string>, Task>? ShowInputDialog { get; set;}
  
         public override void Initialize()
         {

BlazorDemo/Views/MainView.axaml.cs

@@ -27,13 +27,12 @@ namespace BlazorDemo.Views
             }
         }
 
-        private void Callback(MemoryStream stream, string name)
+        private void Callback(Stream stream, string name)
         {
             var text = this.FindControl<TextBox>("text");
             if (text is { })
             {
                 Console.WriteLine($"Callback(): {name}");
-                stream.Position = 0;
                 using var reader = new StreamReader(stream);
                 var str = reader.ReadToEnd();
                 text.Text = str;