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Merge pull request #1120 from abarth/fewer_handlers

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Don't register gesture detectors when Scrollable can't scroll
This commit is contained in:
Adam Barth 2015-09-10 12:10:09 -07:00
commit d76f5652e6
2 changed files with 21 additions and 5 deletions
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3
packages/flutter/lib/src/animation/scroll_behavior.dart
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@ -19,6 +19,9 @@ abstract class ScrollBehavior {
/// The new scroll offset to use when the user attempts to scroll from the given offset by the given delta
double applyCurve(double scrollOffset, double scrollDelta);
/// Whether this scroll behavior currently permits scrolling
bool get isScrollable => true;
}
/// A scroll behavior for a scrollable widget with linear extent

23
packages/flutter/lib/src/widgets/scrollable.dart
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@ -9,6 +9,7 @@ import 'dart:sky' as sky;
import 'package:newton/newton.dart';
import 'package:sky/animation.dart';
import 'package:sky/gestures/constants.dart';
import 'package:sky/gestures/scroll.dart';
import 'package:sky/src/rendering/box.dart';
import 'package:sky/src/rendering/viewport.dart';
import 'package:sky/src/widgets/basic.dart';
@ -79,13 +80,25 @@ abstract class Scrollable extends StatefulComponent {
Widget buildContent();
GestureDragUpdateCallback _getDragUpdateHandler(ScrollDirection direction) {
if (scrollDirection != direction || !scrollBehavior.isScrollable)
return null;
return scrollBy;
}
GestureDragEndCallback _getDragEndHandler(ScrollDirection direction) {
if (scrollDirection != direction || !scrollBehavior.isScrollable)
return null;
return _maybeSettleScrollOffset;
}
Widget build() {
return new GestureDetector(
onVerticalDragUpdate: scrollDirection == ScrollDirection.vertical ? scrollBy : null,
onVerticalDragEnd: scrollDirection == ScrollDirection.vertical ? _maybeSettleScrollOffset : null,
onHorizontalDragUpdate: scrollDirection == ScrollDirection.horizontal ? scrollBy : null,
onHorizontalDragEnd: scrollDirection == ScrollDirection.horizontal ? _maybeSettleScrollOffset : null,
onFling: _handleFling,
onVerticalDragUpdate: _getDragUpdateHandler(ScrollDirection.vertical),
onVerticalDragEnd: _getDragEndHandler(ScrollDirection.vertical),
onHorizontalDragUpdate: _getDragUpdateHandler(ScrollDirection.horizontal),
onHorizontalDragEnd: _getDragEndHandler(ScrollDirection.horizontal),
onFling: scrollBehavior.isScrollable ? _handleFling : null,
child: new Listener(
child: buildContent(),
onPointerDown: _handlePointerDown,