Flutter-Layout-Cheat-Sheet

This repo includes identified Flutter Layouts which anyone can refer as their layout cheat sheet.

AnimatedBuilder class

A general-purpose widget for building animations.

Performance optimizations

If your builder function contains a subtree that does not depend on the animation, it's more efficient to build that subtree once instead of rebuilding it on every animation tick.

If you pass the pre-built subtree as the child parameter, the AnimatedBuilder will pass it back to your builder function so that you can incorporate it into your build.

Using this pre-built child is entirely optional, but can improve performance significantly in some cases and is therefore a good practice.

link

Sample

This code defines a widget called Spinner that spins a green square continually. It is built with an AnimatedBuilder and makes use of the child feature to avoid having to rebuild the Container each time.

assignment

class Spinner extends StatefulWidget {
  @override
  _SpinnerState createState() => _SpinnerState();
}

class _SpinnerState extends State<Spinner> with SingleTickerProviderStateMixin {
  AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 10),
      vsync: this,
    )..repeat();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _controller,
      child: Container(width: 200.0, height: 200.0, color: Colors.green),
      builder: (BuildContext context, Widget child) {
        return Transform.rotate(
          angle: _controller.value * 2.0 * math.pi,
          child: child,
        );
      },
    );
  }
}

Inheritance

• Object
• Diagnosticable
• DiagnosticableTree
• Widget
• StatefulWidget
• AnimatedWidget
• AnimatedBuilder

Constructors

AnimatedBuilder({Key key, @required Listenable animation, @required TransitionBuilder builder, Widget child })

Creates an animated builder. [...]

const

Properties

builder → TransitionBuilder

Called every time the animation changes value.

final

child → Widget

The child widget to pass to the builder. [...]

final

hashCode → int

The hash code for this object. [...]

read-only, inherited

key → Key

Controls how one widget replaces another widget in the tree. [...]

final, inherited

listenable → Listenable

The Listenable to which this widget is listening. [...]

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

read-only, inherited

Methods

build(BuildContext context) → Widget

Override this method to build widgets that depend on the state of the listenable (e.g., the current value of the animation).

override

createElement() → StatefulElement

Creates a StatefulElement to manage this widget's location in the tree. [...]

inherited

createState() → _AnimatedState

Subclasses typically do not override this method.

inherited

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children. [...]

@protected, inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node. [...]

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a non-existent method or property is accessed. [...]

inherited

toDiagnosticsNode({String name, DiagnosticsTreeStyle style }) → DiagnosticsNode

Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep. [...]

inherited

toString({DiagnosticLevel minLevel: DiagnosticLevel.debug }) → String

Returns a string representation of this object.

inherited

toStringDeep({String prefixLineOne: '', String prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug }) → String

Returns a string representation of this node and its descendants. [...]

inherited

toStringShallow({String joiner: ', ', DiagnosticLevel minLevel: DiagnosticLevel.debug }) → String

Returns a one-line detailed description of the object. [...]

inherited

toStringShort() → String

A short, textual description of this widget.

inherited

Operators

operator ==(dynamic other) → bool

The equality operator. [...]

inherited

1. CONSTRUCTORS
2. AnimatedBuilder
3. PROPERTIES
4. builder
5. child
6. hashCode
7. key
8. listenable
9. runtimeType
10. METHODS
11. build
12. createElement
13. createState
14. debugDescribeChildren
15. debugFillProperties
16. noSuchMethod
17. toDiagnosticsNode
18. toString
19. toStringDeep
20. toStringShallow
21. toStringShort
22. OPERATORS
23. operator ==

Flutter 1.9.1+hotfix.5 •