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Switch TabBar to sliver-based scrolling (#7964)

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This commit is contained in:
Adam Barth 2017-02-08 10:34:15 -08:00 committed by GitHub
parent 1a066c8404
commit 2116f00b5f
2 changed files with 24 additions and 18 deletions
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31
packages/flutter/lib/src/material/tabs.dart
View File

@ -385,7 +385,7 @@ class TabBar extends StatefulWidget implements AppBarBottomWidget {
}
class _TabBarState extends State<TabBar> {
final GlobalKey<ScrollableState> viewportKey = new GlobalKey<ScrollableState>();
final ScrollController _scrollController = new ScrollController();
TabController _controller;
_ChangeAnimation _changeAnimation;
@ -434,28 +434,25 @@ class _TabBarState extends State<TabBar> {
// tabOffsets[tabOffsets.length] is the right edge of the last tab.
int get maxTabIndex => _indicatorPainter.tabOffsets.length - 2;
double _tabCenteredScrollOffset(ScrollableState viewport, int tabIndex) {
double _tabCenteredScrollOffset(int tabIndex) {
final List<double> tabOffsets = _indicatorPainter.tabOffsets;
assert(tabOffsets != null && tabIndex >= 0 && tabIndex <= maxTabIndex);
final ExtentScrollBehavior scrollBehavior = viewport.scrollBehavior;
final double viewportWidth = scrollBehavior.containerExtent;
final ScrollPosition position = _scrollController.position;
final double tabCenter = (tabOffsets[tabIndex] + tabOffsets[tabIndex + 1]) / 2.0;
return (tabCenter - viewportWidth / 2.0)
.clamp(scrollBehavior.minScrollOffset, scrollBehavior.maxScrollOffset);
return (tabCenter - position.viewportDimension / 2.0)
.clamp(position.minScrollExtent, position.maxScrollExtent);
}
void _scrollToCurrentIndex() {
final ScrollableState viewport = viewportKey.currentState;
final double offset = _tabCenteredScrollOffset(viewport, _currentIndex);
viewport.scrollTo(offset, duration: kTabScrollDuration);
final double offset = _tabCenteredScrollOffset(_currentIndex);
_scrollController.animateTo(offset, duration: kTabScrollDuration, curve: Curves.ease);
}
void _scrollToControllerValue() {
final ScrollableState viewport = viewportKey.currentState;
final double left = _currentIndex > 0 ? _tabCenteredScrollOffset(viewport, _currentIndex - 1) : null;
final double middle = _tabCenteredScrollOffset(viewport, _currentIndex);
final double right = _currentIndex < maxTabIndex ? _tabCenteredScrollOffset(viewport, _currentIndex + 1) : null;
final double left = _currentIndex > 0 ? _tabCenteredScrollOffset(_currentIndex - 1) : null;
final double middle = _tabCenteredScrollOffset(_currentIndex);
final double right = _currentIndex < maxTabIndex ? _tabCenteredScrollOffset(_currentIndex + 1) : null;
final double index = _controller.index.toDouble();
final double value = _controller.animation.value;
@ -471,7 +468,7 @@ class _TabBarState extends State<TabBar> {
else
offset = right == null ? middle : lerpDouble(middle, right, value - index);
viewport.scrollTo(offset);
_scrollController.jumpTo(offset);
}
void _handleTick() {
@ -582,10 +579,10 @@ class _TabBarState extends State<TabBar> {
);
if (config.isScrollable) {
tabBar = new ScrollableViewport(
scrollableKey: viewportKey,
tabBar = new SingleChildScrollView(
scrollDirection: Axis.horizontal,
child: tabBar
controller: _scrollController,
child: tabBar,
);
}

11
packages/flutter/lib/src/widgets/single_child_scroll_view.dart
View File

@ -8,9 +8,10 @@ import 'package:flutter/rendering.dart';
import 'basic.dart';
import 'framework.dart';
import 'scroll_controller.dart';
import 'scroll_physics.dart';
import 'scrollable.dart';
/// A box in which a single widget can be scrolled.
///
/// This widget is useful when you have a single box that will normally be
@ -41,6 +42,8 @@ class SingleChildScrollView extends StatelessWidget {
this.scrollDirection: Axis.vertical,
this.reverse: false,
this.padding,
this.physics,
this.controller,
this.child,
}) : super(key: key) {
assert(scrollDirection != null);
@ -52,6 +55,10 @@ class SingleChildScrollView extends StatelessWidget {
final EdgeInsets padding;
final ScrollController controller;
final ScrollPhysics physics;
final Widget child;
AxisDirection _getDirection(BuildContext context) {
@ -73,6 +80,8 @@ class SingleChildScrollView extends StatelessWidget {
contents = new Padding(padding: padding, child: contents);
return new Scrollable2(
axisDirection: axisDirection,
controller: controller,
physics: physics,
viewportBuilder: (BuildContext context, ViewportOffset offset) {
return new _SingleChildViewport(
key: key,