A widget that supports the Material "swipe to refresh" idiom.

When the child's Scrollable descendant overscrolls, an animated circular progress indicator is faded into view. When the scroll ends, if the indicator has been dragged far enough for it to become completely opaque, the onRefresh callback is called. The callback is expected to update the scrollable's contents and then complete the Future it returns. The refresh indicator disappears after the callback's Future has completed.

If the Scrollable might not have enough content to overscroll, consider settings its physics property to AlwaysScrollableScrollPhysics:

new ListView(
  physics: const AlwaysScrollableScrollPhysics(),
  children: ...

Using AlwaysScrollableScrollPhysics will ensure that the scroll view is always scrollable and, therefore, can trigger the RefreshIndicator.

A RefreshIndicator can only be used with a vertical scroll view.

See also:

Inheritance

Constructors

RefreshIndicator({Key key, @required Widget child, double displacement: 40.0, @required RefreshCallback onRefresh, Color color, Color backgroundColor, ScrollNotificationPredicate notificationPredicate: defaultScrollNotificationPredicate })
Creates a refresh indicator. [...]
const

Properties

backgroundColor Color
The progress indicator's background color. The current theme's ThemeData.canvasColor by default.
final
child Widget
The refresh indicator will be stacked on top of this child. The indicator will appear when child's Scrollable descendant is over-scrolled.
final
color Color
The progress indicator's foreground color. The current theme's ThemeData.accentColor by default.
final
displacement double
The distance from the child's top or bottom edge to where the refresh indicator will settle. During the drag that exposes the refresh indicator, its actual displacement may significantly exceed this value.
final
notificationPredicate ScrollNotificationPredicate
A check that specifies whether a ScrollNotification should be handled by this widget. [...]
final
onRefresh RefreshCallback
A function that's called when the user has dragged the refresh indicator far enough to demonstrate that they want the app to refresh. The returned Future must complete when the refresh operation is finished.
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
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited

Methods

createState() RefreshIndicatorState
Creates the mutable state for this widget at a given location in the tree. [...]
createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree. [...]
inherited
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children. [...]
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder description) → 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 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 ==(other) bool
The equality operator. [...]
inherited