RefreshIndicator class Null safety

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.

The trigger mode is configured by RefreshIndicator.triggerMode.

Troubleshooting

Refresh indicator does not show up

The RefreshIndicator will appear if its scrollable descendant can be overscrolled, i.e. if the scrollable's content is bigger than its viewport. To ensure that the RefreshIndicator will always appear, even if the scrollable's content fits within its viewport, set the scrollable's Scrollable.physics property to AlwaysScrollableScrollPhysics:

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

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

See also:

Inheritance

Constructors

RefreshIndicator({Key? key, required Widget child, double displacement, double edgeOffset, required RefreshCallback onRefresh, Color? color, Color? backgroundColor, ScrollNotificationPredicate notificationPredicate, String? semanticsLabel, String? semanticsValue, double strokeWidth, RefreshIndicatorTriggerMode triggerMode})
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 widget below this widget in the tree. [...]
final
color Color?
The progress indicator's foreground color. The current theme's ColorScheme.primary by default.
final
displacement double
The distance from the child's top or bottom edgeOffset where the refresh indicator will settle. During the drag that exposes the refresh indicator, its actual displacement may significantly exceed this value. [...]
final
edgeOffset double
The offset where RefreshProgressIndicator starts to appear on drag start. [...]
final
hashCode int
The hash code for this object. [...]
@nonVirtual, read-only, inherited
key Key?
Controls how one widget replaces another widget in the tree. [...]
final, inherited
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
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited
semanticsLabel String?
The SemanticsProperties.label for this progress indicator. [...]
final
semanticsValue String?
The SemanticsProperties.value for this progress indicator. [...]
final
strokeWidth double
Defines strokeWidth for RefreshIndicator. [...]
final
triggerMode RefreshIndicatorTriggerMode
Defines how this RefreshIndicator can be triggered when users overscroll. [...]
final

Methods

createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree. [...]
inherited
createState() RefreshIndicatorState
Creates the mutable state for this widget at a given location in the tree. [...]
override
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.info}) String
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 ==(Object other) bool
The equality operator. [...]
@nonVirtual, inherited