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Improve dartdoc for GlobalKey

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Fixes #2708
This commit is contained in:
Adam Barth 2016-03-15 13:43:42 -07:00
parent dac1d4a15f
commit 5a92e2d0da
1 changed files with 15 additions and 3 deletions
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18
packages/flutter/lib/src/widgets/framework.dart
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@ -84,9 +84,21 @@ class ObjectKey extends Key {
typedef void GlobalKeyRemoveListener(GlobalKey key);
/// A GlobalKey is one that must be unique across the entire application. It is
/// used by widgets that need to communicate with other widgets across the
/// application's element tree.
/// A GlobalKey is a [Key] that must be unique across the widget tree.
///
/// Global keys uniquely indentify widget subtrees. The GlobalKey object provides
/// access to other objects that are associated with the subtree, such as the subtree's
/// [BuildContext] and, for [StatefulWidget]s, the subtree's [State].
///
/// Widgets that have global keys reparent their subtrees when they are moved
/// from one location in the tree to another location in the tree. In order to
/// reparent its subtree, a widget must arrive at its new location in the tree
/// in the same animation frame in which it was removed from its old location in
/// the tree.
///
/// GlobalKeys are relatively expensive. If you don't need any of the features
/// listed above, consider using a [Key], [ValueKey], [ObjectKey], or
/// [UniqueKey] instead.
abstract class GlobalKey<T extends State<StatefulWidget>> extends Key {
/// Constructs a LabeledGlobalKey, which is a GlobalKey with a label used for debugging.
/// The label is not used for comparing the identity of the key.