ScrollDragController class
Scrolls a scroll view as the user drags their finger across the screen.
See also:
- DragScrollActivity, which is the activity the scroll view performs while a drag is underway.
- Implemented types
Constructors
- ScrollDragController({required ScrollActivityDelegate delegate, required DragStartDetails details, VoidCallback? onDragCanceled, double? carriedVelocity, double? motionStartDistanceThreshold})
- Creates an object that scrolls a scroll view as the user drags their finger across the screen.
Properties
- carriedVelocity → double?
-
Velocity that was present from a previous ScrollActivity when this drag
began.
final
- delegate → ScrollActivityDelegate
-
The object that will actuate the scroll view as the user drags.
no setter
- hashCode → int
-
The hash code for this object.
no setterinherited
- lastDetails → dynamic
-
The most recently observed DragStartDetails, DragUpdateDetails, or
DragEndDetails object.
no setter
- motionStartDistanceThreshold → double?
-
Amount of pixels in either direction the drag has to move by to start
scroll movement again after each time scrolling came to a stop.
final
- onDragCanceled → VoidCallback?
-
Called when dispose is called.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
Methods
-
cancel(
) → void -
The input from the pointer is no longer directed towards this receiver.
override
-
dispose(
) → void - Called by the delegate when it is no longer sending events to this object.
-
end(
DragEndDetails details) → void -
The pointer is no longer in contact with the screen.
override
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
toString(
) → String -
A string representation of this object.
override
-
update(
DragUpdateDetails details) → void -
The pointer has moved.
override
-
updateDelegate(
ScrollActivityDelegate value) → void - Updates the controller's link to the ScrollActivityDelegate.
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited
Constants
- momentumRetainStationaryDurationThreshold → const Duration
- Maximum amount of time interval the drag can have consecutive stationary pointer update events before losing the momentum carried from a previous scroll activity.
- momentumRetainVelocityThresholdFactor → const double
- The minimum amount of velocity needed to apply the carriedVelocity at the end of a drag. Expressed as a factor. For example with a carriedVelocity of 2000, we will need a velocity of at least 1000 to apply the carriedVelocity as well. If the velocity does not meet the threshold, the carriedVelocity is lost. Decided by fair eyeballing with the scroll_overlay platform test.
- motionStoppedDurationThreshold → const Duration
- Maximum amount of time interval the drag can have consecutive stationary pointer update events before needing to break the motionStartDistanceThreshold to start motion again.
