merge from original master

README.md

@@ -509,3 +509,231 @@ The following animation is done with just `AnimatedContainer()`
 [play with the animation in codepen](https://codepen.io/erluxman/pen/MWaEZEz)
 
 ![](assets/28animatedcontainer.gif)
+
+
+## #Day29 Wrap widget
+
+When you are making responsive UIs, you need to wrap contents dynamically.
+
+Wrap comes to the rescue. Wrap is like Column/Row but wraps it's children to next row or column.
+
+Use Wrap like you use Column or Row just give it's direction (either vertical or horizontal)
+
+    Wrap(
+        direction: Axis.vertical/Axis.horizontal,
+        children: [Widgets],
+        runAlignment: WrapAlignment.start,
+        spacing: 20, //space between previous and next item
+        runSpacing: 20, //space between new row or column
+        );
+[try in codepen](https://codepen.io/erluxman/pen/YzyENpR)
+![](assets/29wrap.gif)
+
+
+
+
+## #Day30 Blur a Widget in Flutter
+
+To blur a widget, put it below a BackdropFilter widget in stack. 
+
+1. Adjust Gussian blur level with sigmaX, and sigmaY.
+2. Must provide child to Backdrop it needs a layer to act as blur.
+
+
+        Stack(
+            fit: StackFit.loose,
+            children: <Widget>[
+            FlutterLogo(size: 300),
+            Positioned.fill(
+                child: BackdropFilter(
+                filter: ImageFilter.blur(sigmaX: 5, sigmaY: 5),
+                child: Container(
+                    color: Colors.transparent,
+                ),),
+            ],
+        )
+
+
+You will a blur like this.
+[play in codepen](https://codepen.io/erluxman/pen/xxwPJrY)
+![](assets/30blur.png)
+
+## #Day31 Changing Theme Dynamically
+
+Theme of the application is nothing but argument in MaterialApp or CupertinoApp.
+
+Just create a StreamController of bool to represent it's theme.
+
+With the use of StreamBuilder, set the theme of inside Material/Cupertino App and boom 🚀 your app will be able to change it's theme dynamically.
+
+    //Define a Inherited Widget
+    class SettingsStore extends InheritedWidget {
+        final ValueNotifier<ThemeData> theme = ValueNotifier(ThemeData.light());
+
+        SettingsStore({@required Widget child}) : super(child: child);
+
+        static SettingsStore of(BuildContext context) =>
+        context.dependOnInheritedWidgetOfExactType<SettingsStore>();
+
+        void updateTheme(ThemeData theme) => this.theme.value = theme;
+
+        @override
+        bool updateShouldNotify(SettingsStore oldWidget) => oldWidget.theme != this.theme;
+    }
+
+
+    //Listen to it
+    class App extends StatelessWidget {
+        @override
+        Widget build(BuildContext context) {
+            return ValueListenableBuilder(
+                valueListenable: SettingsStore.of(context).theme,
+                builder: (context, theme, child) => MaterialApp(
+                theme: theme,
+                home: SettingsView(),),
+            );
+        }
+    }
+
+
+
+    //Change the theme from any build method.
+    SettingsStore.of(context).updateTheme(ThemeData.light())
+
+
+Credit: [u/Kounex's](https://www.reddit.com/user/Kounex/)
+
+[try on dartpad](https://dartpad.dartlang.org/ccac4c4dff07d69deb6fcacbdeebaa3c)
+
+
+![](assets/32dynamictheme.gif)
+
+
+## #Day32 Dart Extension
+
+We can extend functionality to existing class/API/Library without inheriting it to a child class.
+
+Extensions can have method, getter and setter.
+
+Here we add function to DateTime class without subclassing it.
+
+Define extension like this :
+
+    extension DateExtensions on DateTime{
+
+        printYYYYMMdd(String seperator) {
+            var dateString = "${this.year}$seperator${getTwoDigit(this.month)}$seperator${getTwoDigit(this.day)}";
+            print(dateString);
+        }
+
+        String getTwoDigit(int number){
+            return (number < 10)? "0$number" :number.toString();
+        }
+
+        DateTime get  nextYear => this.add(Duration(days:365));
+
+        DateTime previousYear() => this.subtract(Duration(days:365));
+    }
+
+Then Just Call those extensions 
+
+    void main() {
+        var now = DateTime.now();
+        var nextYear = now.nextYear;
+        var lastYear = now.previousYear();
+
+        now.printYYYYMMdd("-");
+        nextYear.printYYYYMMdd("/");
+        previousYear.printYYYYMMdd(".");
+    }
+
+
+[try on dartpad](https://dartpad.dartlang.org/45e30e5208b39123053f2408624d641c)
+
+
+## #Day33 ToastBadge (toast_badge) package
+
+If you want to show notification that auto dismisses anywhere in the screen, use `toast_badge`. 
+
+Just wrap any widget with `ToastBadget` or call `.enableBadge()` on any widget, you will be able to show notification on that widget without the need of BuildContext object. 
+
+i.e. You use it like toast but in the place you desire. 
+
+1. Wrap 
+
+
+        child: ToastBadge( child: SettingPage(),),
+
+
+        //OR 
+
+        child: SettingPage().enableBadge(),
+
+2. Call 
+
+
+        ToastBadge.show("Hello Toast");
+
+
+        //With more options
+
+        ToastBadge.show("Hello Toast",  
+        mode: ToastMode.INFO, 
+        duration: Duration(milliseconds: 500));
+
+
+[use this package](https://github.com/erluxman/toast_badge)
+
+![](assets/33toastbadge.gif)
+
+
+## #Day34 Making Reorderable list. 
+
+Create ReorderableListView just like normal ListView.
+
+1. Give Key to each child
+2. Handle onReorder: (oldIndex, newIndex)
+
+
+        ReorderableListView(
+              onReorder: (oldIndex, newIndex) {
+                setState(() {
+                  if (oldIndex < newIndex) {
+                    newIndex -= 1;
+                  }
+                  var previous = names.removeAt(oldIndex);
+                  names.insert(newIndex, previous);
+                });
+              },
+              children:[
+                child(key:ObjectKey(item)),.....
+              ]
+        )
+
+[try in codepen](https://codepen.io/erluxman/pen/Yzyabpz)
+
+![](assets/34reorderable.gif)
+
+
+## #Day35 Dart Dev tools
+
+Dart dev tool is powerful set of debugging and performance tools like Layout Inspector,Timeline, Memory, App Performance,Debugger,Logging & Network monitor.
+
+Android Stidio : You can open it by clicking dart icon on Run tab when app is runnin in Anadroid Studio
+
+VSCode: typing Open Dev Tools in command Pallet.
+
+Learining to use Dart Dev tool  is very 🚨important skill🚨 to have as a Flutter/dart developer.
+
+![Opening in Android Studio](assets/35as.png)
+_Opening in Android Stuido_ 
+
+
+![](assets/35vscode.png)
+_Opening in VSCode_
+
+
+![](assets/35devtools.png)
+_Dev tools page_ 
+
+[See amazing dart dev tool gifs](https://www.google.com/search?q=dart+devtools+gif&tbm=isch&rlz=1C5CHFA_enNP896NP896&hl=en&ved=2ahUKEwjG5J75pqjpAhW8A7cAHTFmCdYQBXoECAEQKA&biw=1920&bih=1066)