ScrollMetrics mixin
A description of a Scrollable's contents, useful for modeling the state of its viewport.
This class defines a current position, pixels, and a range of values considered "in bounds" for that position. The range has a minimum value at minScrollExtent and a maximum value at maxScrollExtent (inclusive). The viewport scrolls in the direction and axis described by axisDirection and axis.
The outOfRange getter will return true if pixels is outside this defined range. The atEdge getter will return true if the pixels position equals either the minScrollExtent or the maxScrollExtent.
The dimensions of the viewport in the given axis are described by viewportDimension.
The above values are also exposed in terms of extentBefore, extentInside, and extentAfter, which may be more useful for use cases such as scroll bars; for example, see Scrollbar.
To create a local project with this code sample, run:
flutter create --sample=widgets.ScrollMetrics.1 mysample
See also:
- FixedScrollMetrics, which is an immutable object that implements this interface.
- Mixin Applications
Properties
- atEdge → bool
-
Whether the pixels value is exactly at the minScrollExtent or the
maxScrollExtent.
no setter
- axis → Axis
-
The axis in which the scroll view scrolls.
no setter
- axisDirection → AxisDirection
-
The direction in which the scroll view scrolls.
no setter
- devicePixelRatio → double
-
The FlutterView.devicePixelRatio of the view that the Scrollable
associated with this metrics object is drawn into.
no setter
- extentAfter → double
-
The quantity of content conceptually "below" the viewport in the scrollable.
This is the content below the content described by extentInside.
no setter
- extentBefore → double
-
The quantity of content conceptually "above" the viewport in the scrollable.
This is the content above the content described by extentInside.
no setter
- extentInside → double
-
The quantity of content conceptually "inside" the viewport in the
scrollable (including empty space if the total amount of content is less
than the viewportDimension).
no setter
- extentTotal → double
-
The total quantity of content available.
no setter
- hasContentDimensions → bool
-
Whether the minScrollExtent and the maxScrollExtent properties are available.
no setter
- hashCode → int
-
The hash code for this object.
no setterinherited
- hasPixels → bool
-
Whether the pixels property is available.
no setter
- hasViewportDimension → bool
-
Whether the viewportDimension property is available.
no setter
- maxScrollExtent → double
-
The maximum in-range value for pixels.
no setter
- minScrollExtent → double
-
The minimum in-range value for pixels.
no setter
- outOfRange → bool
-
Whether the pixels value is outside the minScrollExtent and
maxScrollExtent.
no setter
- pixels → double
-
The current scroll position, in logical pixels along the axisDirection.
no setter
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- viewportDimension → double
-
The extent of the viewport along the axisDirection.
no setter
Methods
-
copyWith(
{double? minScrollExtent, double? maxScrollExtent, double? pixels, double? viewportDimension, AxisDirection? axisDirection, double? devicePixelRatio}) → ScrollMetrics - Creates a ScrollMetrics that has the same properties as this object.
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
toString(
) → String -
A string representation of this object.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited