Experiment with trying to render an autocomplete box

lib/main_autocomplete.dart

@@ -0,0 +1,133 @@
+import 'package:flutter/material.dart';
+
+void main() => runApp(MyApp());
+
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter  Show Text Tag Demo',
+      debugShowCheckedModeBanner: false,
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      home: MyHomePage(title: 'Flutter Show Text Tag demo'),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  MyHomePage({Key key, this.title}) : super(key: key);
+
+  final String title;
+
+  @override
+  _MyHomePageState createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  FocusNode _focusNode = FocusNode();
+  GlobalKey _textFieldKey = GlobalKey();
+  TextStyle _textFieldStyle = TextStyle(fontSize: 20);
+
+  @override
+  void initState() {
+    super.initState();
+  }
+
+  // Code reference for overlay logic from MTECHVIRAL's video
+  // https://www.youtube.com/watch?v=KuXKwjv2gTY
+
+  // I need to paint it exactly where the cursor is
+
+  void showOverlaidTag(BuildContext context, String newText) async {
+    print('showOverlaidTag: $newText');
+
+    RenderBox renderBox = _textFieldKey.currentContext.findRenderObject();
+    print("render Box: ${renderBox.size}");
+
+    TextPainter painter = TextPainter(
+      textDirection: TextDirection.ltr,
+      text: TextSpan(
+        style: _textFieldStyle,
+        text: newText,
+      ),
+      maxLines: null,
+    );
+    painter.layout(maxWidth: renderBox.size.width);
+
+    print("Focus Node Offset dx: ${_focusNode.offset.dx}");
+    print("Focus Node Offset dy: ${_focusNode.offset.dy}");
+
+    print("Painter ${painter.width} ${painter.height}");
+
+    OverlayState overlayState = Overlay.of(context);
+    OverlayEntry suggestionTagoverlayEntry = OverlayEntry(builder: (context) {
+      return Positioned(
+        // Decides where to place the tag on the screen.
+        top: _focusNode.offset.dy + painter.height + 3,
+        left: _focusNode.offset.dx + painter.width,
+
+        // Tag code.
+        child: const Material(
+            elevation: 4.0,
+            color: Colors.lightBlueAccent,
+            child: Text(
+              'Show tag here',
+              style: TextStyle(
+                fontSize: 20.0,
+              ),
+            )),
+      );
+    });
+    overlayState.insert(suggestionTagoverlayEntry);
+
+    // Removes the over lay entry from the Overly after 500 milliseconds
+    await Future.delayed(Duration(milliseconds: 5000));
+    suggestionTagoverlayEntry.remove();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(widget.title),
+      ),
+      body: Center(
+        child: Container(
+          child: TextField(
+            focusNode: _focusNode,
+            key: _textFieldKey,
+            style: _textFieldStyle,
+            maxLines: null,
+            onChanged: (String nextText) {
+              if (nextText.endsWith('[[')) {
+                showOverlaidTag(context, nextText);
+              }
+            },
+          ),
+          width: 400.0,
+        ),
+      ),
+    );
+  }
+}
+
+class Editor extends StatefulWidget {
+  @override
+  _EditorState createState() => _EditorState();
+}
+
+class _EditorState extends State<Editor> {
+  @override
+  Widget build(BuildContext context) {
+    return Container();
+  }
+}
+// https://pub.dev/packages/rich_input
+// https://levelup.gitconnected.com/flutter-medium-like-text-editor-b41157f50f0e
+
+// https://pub.dev/packages/autocomplete_textfield
+// https://pub.dev/packages/flutter_typeahead
+
+// https://stackoverflow.com/questions/59243627/flutter-how-to-get-the-coordinates-of-the-cursor-in-a-textfield