added keyboard input

lib/main.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 
 void main() {
   runApp(const MyApp());
@@ -51,24 +52,32 @@ class _MyHomePageState extends State<MyHomePage> {
         backgroundColor: Theme.of(context).colorScheme.inversePrimary,
         title: Text(widget.title),
       ),
-      body: Center(
+      body: RawKeyboardListener(
-        child: Column(
+        focusNode: FocusNode(),
-          mainAxisAlignment: MainAxisAlignment.center,
+        autofocus: true,
-          children: <Widget>[
+        onKey: (RawKeyEvent event) {
-            const Text(
+          if (event.isKeyPressed(LogicalKeyboardKey.keyD)) _decrementCounter();
-              'You have pushed the button this many times:',
+          if (event.isKeyPressed(LogicalKeyboardKey.keyI)) _incrementCounter();
-            ),
+        },
-            Text(
+        child: Center(
-              '$_counter',
+          child: Column(
-              style: Theme.of(context).textTheme.headlineMedium,
+            mainAxisAlignment: MainAxisAlignment.center,
-            ),
+            children: <Widget>[
-          ],
+              const Text(
+                'You have pushed the button this many times:',
+              ),
+              Text(
+                '$_counter',
+                style: Theme.of(context).textTheme.headlineMedium,
+              ),
+            ],
+          ),
         ),
       ),
       floatingActionButton: Stack(
         children: <Widget>[
           Padding(
-            padding: EdgeInsets.only(left: 31),
+            padding: const EdgeInsets.only(left: 31),
             child: Align(
               alignment: Alignment.bottomLeft,
               child: FloatingActionButton(