ScrollMetrics class
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.
See also:
- FixedScrollMetrics, which is an immutable object that implements this interface.
- Implementers
Constructors
Properties
- atEdge → bool
-
Whether the pixels value is exactly at the minScrollExtent or the
maxScrollExtent.
read-only
- axis → Axis
-
The axis in which the scroll view scrolls.
read-only
- axisDirection → AxisDirection
-
The direction in which the scroll view scrolls.
read-only
- extentAfter → double
-
The quantity of content conceptually "below" the currently visible content
of the viewport in the scrollable. This is the content below the content
described by extentInside.
read-only
- extentBefore → double
-
The quantity of content conceptually "above" the currently visible content
of the viewport in the scrollable. This is the content above the content
described by extentInside.
read-only
- extentInside → double
-
The quantity of visible content. [...]
read-only
- maxScrollExtent → double
-
The maximum in-range value for pixels. [...]
read-only
- minScrollExtent → double
-
The minimum in-range value for pixels. [...]
read-only
- outOfRange → bool
-
Whether the pixels value is outside the minScrollExtent and
maxScrollExtent.
read-only
- pixels → double
-
The current scroll position, in logical pixels along the axisDirection.
read-only
- viewportDimension → double
-
The extent of the viewport along the axisDirection.
read-only
- hashCode → int
-
The hash code for this object. [...]
read-only, inherited
- runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Methods
-
copyWith(
{double minScrollExtent, double maxScrollExtent, double pixels, double viewportDimension, AxisDirection axisDirection }) → ScrollMetrics - Creates a ScrollMetrics that has the same properties as this object. [...]
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent method or property is accessed. [...]
inherited
-
toString(
) → String -
Returns a string representation of this object.
inherited
Operators
-
operator ==(
dynamic other) → bool -
The equality operator. [...]
inherited