| // Copyright 2015 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| import 'package:flutter/scheduler.dart'; |
| import 'package:flutter/rendering.dart'; |
| |
| import 'framework.dart'; |
| import 'ticker_provider.dart'; |
| |
| /// An interface that [Scrollable] widgets implement in order to use |
| /// [ScrollPosition]. |
| /// |
| /// See also: |
| /// |
| /// * [ScrollableState], which is the most common implementation of this |
| /// interface. |
| /// * [ScrollPosition], which uses this interface to communicate with the |
| /// scrollable widget. |
| abstract class ScrollContext { |
| /// The [BuildContext] that should be used when dispatching |
| /// [ScrollNotification]s. |
| /// |
| /// This context is typically different that the context of the scrollable |
| /// widget itself. For example, [Scrollable] uses a context outside the |
| /// [Viewport] but inside the widgets created by |
| /// [ScrollBehavior.buildViewportChrome]. |
| BuildContext get notificationContext; |
| |
| /// The [BuildContext] that should be used when searching for a [PageStorage]. |
| /// |
| /// This context is typically the context of the scrollable widget itself. In |
| /// particular, it should involve any [GlobalKey]s that are dynamically |
| /// created as part of creating the scrolling widget, since those would be |
| /// different each time the widget is created. |
| BuildContext get storageContext; |
| |
| /// A [TickerProvider] to use when animating the scroll position. |
| TickerProvider get vsync; |
| |
| /// The direction in which the widget scrolls. |
| AxisDirection get axisDirection; |
| |
| /// Whether the contents of the widget should ignore [PointerEvent] inputs. |
| /// |
| /// Setting this value to true prevents the use from interacting with the |
| /// contents of the widget with pointer events. The widget itself is still |
| /// interactive. |
| /// |
| /// For example, if the scroll position is being driven by an animation, it |
| /// might be appropriate to set this value to ignore pointer events to |
| /// prevent the user from accidentally interacting with the contents of the |
| /// widget as it animates. The user will still be able to touch the widget, |
| /// potentially stopping the animation. |
| void setIgnorePointer(bool value); |
| |
| /// Whether the user can drag the widget, for example to initiate a scroll. |
| void setCanDrag(bool value); |
| |
| /// Set the [SemanticsAction]s that should be expose to the semantics tree. |
| void setSemanticsActions(Set<SemanticsAction> actions); |
| } |