CupertinoScrollbarModifier class
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.
{@tool dartpad} This sample shows an app with two scrollables in the same route. Since by default, there is one PrimaryScrollController per route, and they both have a scroll direction of Axis.vertical, they would both try to attach to that controller on mobile platforms. The Scrollbar cannot support multiple positions attached to the same controller, so one ListView, and its Scrollbar have been provided a unique ScrollController. Desktop platforms do not automatically attach to the PrimaryScrollController, requiring ScrollView.primary to be true instead in order to use the PrimaryScrollController.
Alternatively, a new PrimaryScrollController could be created above one of the ListViews.
** See code in examples/api/lib/widgets/scrollbar/raw_scrollbar.0.dart ** {@end-tool}
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.
{@tool snippet}
MaterialApp(
scrollBehavior: const MaterialScrollBehavior()
.copyWith(scrollbars: false),
home: Scaffold(
appBar: AppBar(title: const Text('Home')),
),
)
{@end-tool}
{@tool dartpad} This sample shows how to disable the default Scrollbar for a Scrollable widget to avoid duplicate Scrollbars when running on desktop platforms.
** See code in examples/api/lib/widgets/scrollbar/raw_scrollbar.desktop.0.dart ** {@end-tool}
When dragging a CupertinoScrollbar thumb, the thickness and radius will animate from thickness and radius to thicknessWhileDragging and radiusWhileDragging, respectively.
{@tool dartpad}
This sample shows a CupertinoScrollbar that fades in and out of view as scrolling occurs.
The scrollbar will fade into view as the user scrolls, and fade out when scrolling stops.
The 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.
** See code in examples/api/lib/cupertino/scrollbar/cupertino_scrollbar.0.dart ** {@end-tool}
{@tool dartpad}
When thumbVisibility is true, the scrollbar thumb will remain visible without the
fade animation. This requires that a ScrollController is provided to controller,
or that the PrimaryScrollController is available. isAlwaysShown is
deprecated in favor of thumbVisibility.
** See code in examples/api/lib/cupertino/scrollbar/cupertino_scrollbar.1.dart ** {@end-tool}
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
- StatelessWidget
- SingleChildStatelessModifier
- RawScrollbarModifier
- CupertinoScrollbarModifier
- Available extensions
Constructors
- CupertinoScrollbarModifier({Key? key, Widget? child, ScrollController? controller, ScrollNotificationPredicate notificationPredicate = defaultScrollNotificationPredicate, double thickness = CupertinoScrollbar.defaultThickness, double thicknessWhileDragging = CupertinoScrollbar.defaultThicknessWhileDragging, Radius radius = CupertinoScrollbar.defaultRadius, Radius radiusWhileDragging = CupertinoScrollbar.defaultRadiusWhileDragging, 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
- controller → ScrollController?
-
The ScrollController used to implement Scrollbar dragging.
finalinherited
- crossAxisMargin → double
-
Distance from the scrollbar thumb 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.
no setterinherited
- 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's start and end to the 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
- modifierKey → Key?
-
The actual key of the widget, which Modifier wrapped
finalinherited
- notificationPredicate → ScrollNotificationPredicate
-
A check that specifies whether a ScrollNotification should be
handled by this widget.
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.
no setterinherited
- 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
-
build(
BuildContext context) → Widget -
Describes the part of the user interface represented by this widget.
inherited
-
buildWithChild(
BuildContext context, Widget? child) → Widget -
A build method that receives an extra
childparameter.override -
createElement(
) → SingleChildStatelessElement -
Create a SingleChildStatelessElement
inherited
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of DiagnosticsNode objects describing this node's
children.
inherited
-
debugFillProperties(
DiagnosticPropertiesBuilder properties) → void -
Add additional properties associated with the node.
inherited
-
modified(
) → Modifier -
Available on Widget, provided by the ModifierTransformer extension
Transform normal widget to Modifier -
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent 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, int wrapWidth = 65}) → 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