HelpFocus class

Help with Focus System

Overview

  • Directs keyboard input
  • Terminology:
    • Primary focus
      • Farthest node away from root of tree that has focus
      • Key events propagate from primary focus node to ancestors
    • Focus chain
      • Ordered list of nodes along branch from primary focus node to root
    • Focus Traversal
      • Moving focus from one node to another predictably
      • E.g., pressing tab on keyboard

Elements

Focus Tree

  • Sparsely mirrors widget tree
  • Contains focus nodes

Focus Node

  • Represents widget that can receive focus
  • Has focus: part of the focus chain
    • Handles key events only when it has focus

Focus Scope

  • Focus node which contains a group of focus nodes
  • Limits focus to its nodes
  • Contains info about which nodes were previously focused in its subtree

Focus

  • Widget that owns and manages a focus node

Constructors

HelpFocus()

Properties

hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited