CupertinoScrollbar class Null safety
An iOS style scrollbar.
To add a scrollbar to a ScrollView, simply wrap the scroll view widget in a CupertinoScrollbar widget.
A scrollbar thumb indicates which portion of a ScrollView is actually visible.
By default, the thumb will fade in and out as the child scroll view scrolls. When thumbVisibility is true, the scrollbar thumb will remain visible without the fade animation. This requires that the ScrollController associated with the Scrollable widget is provided to controller, or that the PrimaryScrollController is being used by that Scrollable widget.
If the scrollbar is wrapped around multiple ScrollViews, it only responds to the nearest ScrollView and shows the corresponding scrollbar thumb by default. The notificationPredicate allows the ability to customize which ScrollNotifications the Scrollbar should listen to.
If the child ScrollView is infinitely long, the RawScrollbar will not be painted. In this case, the scrollbar cannot accurately represent the relative location of the visible area, or calculate the accurate delta to apply when dragging on the thumb or tapping on the track.
Interaction
Scrollbars are interactive and can use the PrimaryScrollController if a controller is not set. Interactive Scrollbar thumbs can be dragged along the main axis of the ScrollView to change the ScrollPosition. Tapping along the track exclusive of the thumb will trigger a ScrollIncrementType.page based on the relative position to the thumb.
When using the PrimaryScrollController, it must not be attached to more than one ScrollPosition. ScrollViews that have not been provided a ScrollController and have a ScrollView.scrollDirection of Axis.vertical will automatically attach their ScrollPosition to the PrimaryScrollController. Provide a unique ScrollController to each Scrollable in this case to prevent having multiple ScrollPositions attached to the PrimaryScrollController.
Alternatively, a new PrimaryScrollController could be created above one of the ListViews.
To create a local project with this code sample, run:
flutter create --sample=widgets.RawScrollbar.1 mysample
Automatic Scrollbars on Desktop Platforms
Scrollbars are added to most Scrollable widgets by default on TargetPlatformVariant.desktop platforms. This is done through ScrollBehavior.buildScrollbar as part of an app's ScrollConfiguration. Scrollables that do not use the PrimaryScrollController or have a ScrollController provided to them will receive a unique ScrollController for use with the Scrollbar. In this case, only one Scrollable can be using the PrimaryScrollController, unless interactive is false. To prevent Axis.vertical Scrollables from using the PrimaryScrollController, set ScrollView.primary to false. Scrollable widgets that do not have automatically applied Scrollbars include
Default Scrollbars can be disabled for the whole app by setting a
ScrollBehavior with scrollbars set to false.
MaterialApp(
scrollBehavior: const MaterialScrollBehavior()
.copyWith(scrollbars: false),
home: Scaffold(
appBar: AppBar(title: const Text('Home')),
),
)To create a local project with this code sample, run:
flutter create --sample=widgets.RawScrollbar.3 mysample
When dragging a CupertinoScrollbar thumb, the thickness and radius will animate from thickness and radius to thicknessWhileDragging and radiusWhileDragging, respectively.
thickness of the scrollbar will animate from 6 pixels to the thicknessWhileDragging of 10
when it is dragged by the user. The radius of the scrollbar thumb corners will animate from 34
to the radiusWhileDragging of 0 when the scrollbar is being dragged by the user.
To create a local project with this code sample, run:
flutter create --sample=cupertino.CupertinoScrollbar.1 mysample
thumbVisibility.
To create a local project with this code sample, run:
flutter create --sample=cupertino.CupertinoScrollbar.2 mysample
See also:
- ListView, which displays a linear, scrollable list of children.
- GridView, which displays a 2 dimensional, scrollable array of children.
- Scrollbar, a Material Design scrollbar.
- RawScrollbar, a basic scrollbar that fades in and out, extended by this class to add more animations and behaviors.
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatefulWidget
- RawScrollbar
- CupertinoScrollbar
Constructors
- CupertinoScrollbar({Key? key, required Widget child, ScrollController? controller, bool? thumbVisibility, double thickness = defaultThickness, double thicknessWhileDragging = defaultThicknessWhileDragging, Radius radius = defaultRadius, Radius radiusWhileDragging = defaultRadiusWhileDragging, ScrollNotificationPredicate? notificationPredicate, ScrollbarOrientation? scrollbarOrientation, @Deprecated('Use thumbVisibility instead. ' 'This feature was deprecated after v2.9.0-1.0.pre.') bool? isAlwaysShown})
-
Creates an iOS style scrollbar that wraps the given child.
const
Properties
- child → Widget
-
The widget below this widget in the tree.
finalinherited
- controller → ScrollController?
-
The ScrollController used to implement Scrollbar dragging.
finalinherited
- crossAxisMargin → double
-
Distance from the scrollbar thumb's side to the nearest cross axis edge
in logical pixels.
finalinherited
- fadeDuration → Duration
-
The Duration of the fade animation.
finalinherited
- hashCode → int
-
The hash code for this object.
read-onlyinherited
- interactive → bool?
-
Whether the Scrollbar should be interactive and respond to dragging on the
thumb, or tapping in the track area.
finalinherited
- isAlwaysShown → bool?
-
Indicates that the scrollbar thumb should be visible, even when a scroll
is not underway.
finalinherited
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- mainAxisMargin → double
-
Distance from the scrollbar thumb's start or end to the nearest edge of
the viewport in logical pixels. It affects the amount of available
paint area.
finalinherited
- minOverscrollLength → double?
-
The preferred smallest size the scrollbar thumb can shrink to when viewport is
overscrolled.
finalinherited
- minThumbLength → double
-
The preferred smallest size the scrollbar thumb can shrink to when the total
scrollable extent is large, the current visible viewport is small, and the
viewport is not overscrolled.
finalinherited
- notificationPredicate → ScrollNotificationPredicate
-
A check that specifies whether a ScrollNotification should be
handled by this widget.
finalinherited
- padding → EdgeInsets?
-
The insets by which the scrollbar thumb and track should be padded.
finalinherited
- pressDuration → Duration
-
The Duration of time that a LongPress will trigger the drag gesture of
the scrollbar thumb.
finalinherited
- radius → Radius?
-
The Radius of the scrollbar thumb's rounded rectangle corners.
finalinherited
- radiusWhileDragging → Radius
-
The radius of the scrollbar edges when the scrollbar is being dragged by
the user.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
read-onlyinherited
- scrollbarOrientation → ScrollbarOrientation?
-
Dictates the orientation of the scrollbar.
finalinherited
- shape → OutlinedBorder?
-
The OutlinedBorder of the scrollbar's thumb.
finalinherited
- thickness → double?
-
The thickness of the scrollbar in the cross axis of the scrollable.
finalinherited
- thicknessWhileDragging → double
-
The thickness of the scrollbar when it's being dragged by the user.
final
- thumbColor → Color?
-
The color of the scrollbar thumb.
finalinherited
- thumbVisibility → bool?
-
Indicates that the scrollbar thumb should be visible, even when a scroll
is not underway.
finalinherited
- timeToFade → Duration
-
The Duration of time until the fade animation begins.
finalinherited
- trackBorderColor → Color?
-
The color of the scrollbar track's border.
finalinherited
- trackColor → Color?
-
The color of the scrollbar track.
finalinherited
- trackRadius → Radius?
-
The Radius of the scrollbar track's rounded rectangle corners.
finalinherited
- trackVisibility → bool?
-
Indicates that the scrollbar track should be visible.
finalinherited
Methods
-
createElement(
) → StatefulElement -
Creates a StatefulElement to manage this widget's location in the tree.
inherited
-
createState(
) → RawScrollbarState< CupertinoScrollbar> -
Creates the mutable state for this widget at a given location in the tree.
override
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of
DiagnosticsNodeobjects describing this node's children.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.
inherited
Constants
- defaultRadius → const Radius
-
Default value for radius if it's not specified in CupertinoScrollbar.
Radius.circular(1.5) - defaultRadiusWhileDragging → const Radius
-
Default value for radiusWhileDragging if it's not specified in
CupertinoScrollbar.
Radius.circular(4.0) - defaultThickness → const double
-
Default value for thickness if it's not specified in CupertinoScrollbar.
3 - defaultThicknessWhileDragging → const double
-
Default value for thicknessWhileDragging if it's not specified in
CupertinoScrollbar.
8.0