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2026-11-04 00:33:23 +05:30 · 2026-11-04 00:33:23 +05:30 · 74ae93a96e
commit 74ae93a96e
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--- a/Development/Flutter/States.md
+++ b/Development/Flutter/States.md
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+States
+
+- Function setState should be in the callback function which would be responsible to increment the counter defined inside callback function of setState
+- Instead of using maps of array for loading dynamic widgets we can use for loop too
+```dart
+class _MyHomePageState extends State<MyHomePage> {
+
+  int strength = 0;
+  int sugars = 0;
+	
+  @override
+  Widget build(BuildContext context) {
+
+    void incrementStats(String name) {
+      setState(() {
+        switch (name) {
+          case 'Strength':
+            strength = (strength + 1) % 5;
+            break;
+          case 'Sugars':
+            sugars = (sugars + 1) % 5;
+            break;
+        }
+      }); // end of setState
+    } // end of incrementStatus function
+	  
+	body : TextButton( child: Text('$strength - $sugars'), 
+						onPressed : ()=>incrementStats('Strength'),
+					   )
+  } 
+}
+```
+
+**Control flow**
+with for loop
+```dart
+  for (int i = 0; i < int.parse('${e['amount']}'); i++)
+	  Image.asset(
+		'${e['imagePath']}',
+		width: 25,
+		color: Colors.brown[200],
+		colorBlendMode: BlendMode.multiply,
+	  ),
+```
+if statement
+```dart
+if (int.parse('${e['amount']}') == 0)
+   Text('No ${e['string']}'),
+```
+&nbsp;
+
+**Reusable Widgets**
+in separate file define its class
+```dart
+import 'package:flutter/material.dart';
+
+class StyledBodyText extends StatelessWidget {
+  const StyledBodyText(this.text, {super.key});
+
+  final String text;
+
+  @override
+  Widget build(BuildContext context) {
+    return Text(text,
+        style: TextStyle(
+          color: Colors.brown[900],
+          fontWeight: FontWeight.bold,
+          fontSize: 18,
+        ));
+  }
+}
+
+class StyledButton extends StatelessWidget {
+  const StyledButton({
+    super.key,
+    required this.onPressed,
+    required this.child,
+  });
+
+  final Widget child;
+  final void Function() onPressed;
+
+  @override
+  Widget build(BuildContext context) {
+    return TextButton(
+      style: TextButton.styleFrom(
+        backgroundColor: Colors.brown[700],
+        foregroundColor: Colors.white,
+        shape: const RoundedRectangleBorder(
+          borderRadius: BorderRadius.all(Radius.circular(5)),
+        ), // roundedRectangleBorder
+      ),
+      onPressed: onPressed,
+      child: child,
+    );
+  }
+}
+
+```
+in our main file
+```dart
+
+// for styled text
+Container(
+	width: double.infinity,
+	padding: const EdgeInsets.all(10),
+	decoration: BoxDecoration(color: Colors.brown[300]),
+	child: const StyledBodyText('How I like my coffee ..'),
+	// 'You have pushed the button this many times:',
+  ),
+
+// for styled button
+StyledButton(
+  // style: TextButton.styleFrom(
+  //   backgroundColor: Colors.brown,
+  //   foregroundColor: Colors.white,
+  // ),
+  child: Icon(Icons.add),
+  onPressed: () => incrementStats('${e['string']}'),
+),
+```
+&nbsp;
+
+**Routes**
+- https://docs.flutter.dev/cookbook/navigation/named-routes
+- https://docs.flutter.dev/cookbook/navigation/navigate-with-arguments
+- Consistent Overlay across multiple routes
+```dart
+import 'package:flutter/material.dart';
+
+void main() {
+  runApp(MyApp());
+}
+
+class MyApp extends StatefulWidget {
+  @override
+  _MyAppState createState() => _MyAppState();
+}
+
+class _MyAppState extends State<MyApp> {
+  bool _showOverlay = false;
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Stack(
+        children: [
+          Navigator(
+            onGenerateRoute: (settings) { // Your routes
+              return MaterialPageRoute(
+                builder: (context) {
+                  // Your route/page content
+                  return Scaffold(
+                    appBar: AppBar(title: Text(settings.name ?? 'Home')),
+                    body: Center(child: Text('Page content')),
+                  );
+                },
+              );
+            },
+          ),
+          if (_showOverlay)
+            Positioned.fill( // Overlay widget
+              child: ColoredBox(
+                color: Colors.black.withOpacity(0.5), // Semi-transparent background
+                child: Center(
+                  child: ElevatedButton(
+                    onPressed: () {
+                      setState(() => _showOverlay = false);
+                    },
+                    child: Text('Close Overlay'),
+                  ),
+                ),
+              ),
+            ),
+        ],
+      ),
+    );
+  }
+}
+```
+onGenerateRoute property usecase  for routes '/' and '/video'
+```dart
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      onGenerateRoute: (settings) {
+        switch (settings.name) {
+          case '/':
+            return MaterialPageRoute(builder: (context) => HomePage());
+          case '/video':
+            return MaterialPageRoute(builder: (context) => VideoPage());
+          default:
+            return MaterialPageRoute(
+              builder: (context) => Scaffold( // Handle unknown routes
+                body: Center(child: Text('404 - Page Not Found')),
+              ),
+            );
+        }
+      },
+    );
+  }
+}
+```