ScrollPositionWithSingleContext class Null safety

A scroll position that manages scroll activities for a single ScrollContext.

This class is a concrete subclass of ScrollPosition logic that handles a single ScrollContext, such as a Scrollable. An instance of this class manages ScrollActivity instances, which change what content is visible in the Scrollable's Viewport.

Constructors

ScrollPositionWithSingleContext({required ScrollPhysics physics, required ScrollContext context, double? initialPixels = 0.0, bool keepScrollOffset = true, ScrollPosition? oldPosition, String? debugLabel}): Create a ScrollPosition object that manages its behavior using ScrollActivity objects.

Properties

activity → ScrollActivity?: The currently operative ScrollActivity.
protected">@protectedvisibleForTesting">@visibleForTestingread-onlyinherited
allowImplicitScrolling → bool: Whether a viewport is allowed to change pixels implicitly to respond to a call to RenderObject.showOnScreen.
read-onlyinherited
atEdge → bool: Whether the pixels value is exactly at the minScrollExtent or the maxScrollExtent.
read-onlyinherited
axis → Axis: The axis in which the scroll view scrolls.
read-onlyinherited
axisDirection → AxisDirection: The direction in which the scroll view scrolls.
read-onlyoverride
context → ScrollContext: Where the scrolling is taking place.
finalinherited
debugLabel → String?: A label that is used in the toString output.
finalinherited
extentAfter → double: The quantity of content conceptually "below" the viewport in the scrollable. This is the content below the content described by extentInside.
read-onlyinherited
extentBefore → double: The quantity of content conceptually "above" the viewport in the scrollable. This is the content above the content described by extentInside.
read-onlyinherited
extentInside → double: The quantity of content conceptually "inside" the viewport in the scrollable.
read-onlyinherited
hasContentDimensions → bool: Whether the minScrollExtent and the maxScrollExtent properties are available.
read-onlyinherited
hashCode → int: The hash code for this object.
read-onlyinherited
hasListeners → bool: Whether any listeners are currently registered.
protected">@protectedread-onlyinherited
hasPixels → bool: Whether the pixels property is available.
read-onlyinherited
hasViewportDimension → bool: Whether the viewportDimension property is available.
read-onlyinherited
haveDimensions → bool: Whether viewportDimension, minScrollExtent, maxScrollExtent, outOfRange, and atEdge are available.
read-onlyinherited
isScrollingNotifier → ValueNotifier<bool>: This notifier's value is true if a scroll is underway and false if the scroll position is idle.
finalinherited
keepScrollOffset → bool: Save the current scroll offset with PageStorage and restore it if this scroll position's scrollable is recreated.
finalinherited
maxScrollExtent → double: The maximum in-range value for pixels.
read-onlyinherited
minScrollExtent → double: The minimum in-range value for pixels.
read-onlyinherited
outOfRange → bool: Whether the pixels value is outside the minScrollExtent and maxScrollExtent.
read-onlyinherited
physics → ScrollPhysics: How the scroll position should respond to user input.
finalinherited
pixels → double: The number of pixels to offset the children in the opposite of the axis direction.
read-onlyinherited
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited
userScrollDirection → ScrollDirection: The direction in which the user is trying to change pixels, relative to the viewport's RenderViewportBase.axisDirection.
read-onlyoverride
viewportDimension → double: The extent of the viewport along the axisDirection.
read-onlyinherited

Methods

absorb(ScrollPosition other) → void: Take any current applicable state from the given ScrollPosition.
override
addListener(VoidCallback listener) → void: Register a closure to be called when the object changes.
inherited
animateTo(double to, {required Duration duration, required Curve curve}) → Future<void>: Animates the position from its current value to the given value.
override
applyBoundaryConditions(double value) → double: Returns the overscroll by applying the boundary conditions.
protected">@protectedinherited
applyContentDimensions(double minScrollExtent, double maxScrollExtent) → bool: Called when the viewport's content extents are established.
inherited
applyNewDimensions() → void: Notifies the activity that the dimensions of the underlying viewport or contents have changed.
override
applyUserOffset(double delta) → void: Updates the scroll position by the given amount.
override
applyViewportDimension(double viewportDimension) → bool: Called when the viewport's extents are established.
inherited
beginActivity(ScrollActivity? newActivity) → void: Change the current activity, disposing of the old one and sending scroll notifications as necessary.
override
copyWith({double? minScrollExtent, double? maxScrollExtent, double? pixels, double? viewportDimension, AxisDirection? axisDirection}) → ScrollMetrics: Creates a ScrollMetrics that has the same properties as this object.
inherited
correctBy(double correction) → void: Apply a layout-time correction to the scroll offset.
inherited
correctForNewDimensions(ScrollMetrics oldPosition, ScrollMetrics newPosition) → bool: Verifies that the new content and viewport dimensions are acceptable.
protected">@protectedinherited
correctPixels(double value) → void: Change the value of pixels to the new value, without notifying any customers.
inherited
debugFillDescription(List<String> description) → void: Add additional information to the given description for use by toString.
override
didEndScroll() → void: Called by beginActivity to report when an activity has ended.
inherited
didOverscrollBy(double value) → void: Called by setPixels to report overscroll when an attempt is made to change the pixels position. Overscroll is the amount of change that was not applied to the pixels value.
inherited
didStartScroll() → void: Called by beginActivity to report when an activity has started.
inherited
didUpdateScrollDirection(ScrollDirection direction) → void: Dispatches a notification that the userScrollDirection has changed.
inherited
didUpdateScrollMetrics() → void: Dispatches a notification that the ScrollMetrics have changed.
inherited
didUpdateScrollPositionBy(double delta) → void: Called by setPixels to report a change to the pixels position.
inherited
dispose() → void: Discards any resources used by the object. After this is called, the object is not in a usable state and should be discarded (calls to addListener will throw after the object is disposed).
override
drag(DragStartDetails details, VoidCallback dragCancelCallback) → Drag: Start a drag activity corresponding to the given DragStartDetails.
override
ensureVisible(RenderObject object, {double alignment = 0.0, Duration duration = Duration.zero, Curve curve = Curves.ease, ScrollPositionAlignmentPolicy alignmentPolicy = ScrollPositionAlignmentPolicy.explicit, RenderObject? targetRenderObject}) → Future<void>: Animates the position such that the given object is as visible as possible by just scrolling this position.
inherited
forcePixels(double value) → void: Change the value of pixels to the new value, and notify any customers, but without honoring normal conventions for changing the scroll offset.
protected">@protectedinherited
goBallistic(double velocity) → void: Start a physics-driven simulation that settles the pixels position, starting at a particular velocity.
override
goIdle() → void: Terminate the current activity and start an idle activity.
override
hold(VoidCallback holdCancelCallback) → ScrollHoldController: Stop the current activity and start a HoldScrollActivity.
override
jumpTo(double value) → void: Jumps the scroll position from its current value to the given value, without animation, and without checking if the new value is in range.
override
jumpToWithoutSettling(double value) → void: Deprecated. Use jumpTo or a custom ScrollPosition instead.
Deprecated('This will lead to bugs.')">@Deprecated('This will lead to bugs.')override
moveTo(double to, {Duration? duration, Curve? curve, bool? clamp = true}) → Future<void>: Calls jumpTo if duration is null or Duration.zero, otherwise animateTo is called.
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a non-existent method or property is accessed.
inherited
notifyListeners() → void: Call all the registered listeners.
inherited
pointerScroll(double delta) → void: Changes the scrolling position based on a pointer signal from current value to delta without animation and without checking if new value is in range, taking min/max scroll extent into account.
override
recommendDeferredLoading(BuildContext context) → bool: Provides a heuristic to determine if expensive frame-bound tasks should be deferred.
inherited
removeListener(VoidCallback listener) → void: Remove a previously registered closure from the list of closures that are notified when the object changes.
inherited
restoreOffset(double offset, {bool initialRestore = false}) → void: Called by context to restore the scroll offset to the provided value.
inherited
restoreScrollOffset() → void: Called whenever the ScrollPosition is created, to restore the scroll offset if possible.
protected">@protectedinherited
saveOffset() → void: Called whenever scrolling ends, to persist the current scroll offset for state restoration purposes.
protected">@protectedinherited
saveScrollOffset() → void: Called whenever scrolling ends, to store the current scroll offset in a storage mechanism with a lifetime that matches the app's lifetime.
protected">@protectedinherited
setPixels(double newPixels) → double: Update the scroll position (pixels) to a given pixel value.
override
toString() → String: A string representation of this object.
inherited
updateUserScrollDirection(ScrollDirection value) → void: Set userScrollDirection to the given value.
protected">@protectedvisibleForTesting">@visibleForTesting

Operators

operator ==(Object other) → bool: The equality operator.
inherited

ScrollPositionWithSingleContext class Null safety

Constructors

Properties

Methods

Operators

widgets library