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Use _ScaffoldLayout to position scrollable appbars

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This commit is contained in:
Hans Muller 2016-03-29 12:26:32 -07:00
parent f4603f7615
commit 04e020590d
2 changed files with 18 additions and 21 deletions
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9
examples/material_gallery/lib/gallery/home.dart
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@ -50,13 +50,15 @@ class GalleryHome extends StatefulWidget {
}
class GalleryHomeState extends State<GalleryHome> {
final Key _scrollableKey = new UniqueKey();
final Key _homeKey = new ValueKey<String>("Gallery Home");
final Key _listKey = new ValueKey<String>("Gallery List");
@override
Widget build(BuildContext context) {
final double statusBarHight = (MediaQuery.of(context)?.padding ?? EdgeInsets.zero).top;
return new Scaffold(
key: _homeKey,
drawer: new GalleryDrawer(),
appBar: new AppBar(
expandedHeight: _kFlexibleSpaceMaxHeight,
@ -65,13 +67,12 @@ class GalleryHomeState extends State<GalleryHome> {
title: new Text("Flutter Gallery")
)
),
scrollableKey: _scrollableKey,
scrollableKey: _listKey,
appBarBehavior: AppBarBehavior.under,
body: new TwoLevelList(
scrollablePadding: new EdgeInsets.only(top: _kFlexibleSpaceMaxHeight + statusBarHight),
key: _scrollableKey,
type: MaterialListType.oneLine,
scrollableKey: _scrollableKey,
scrollableKey: _listKey,
items: <Widget>[
new TwoLevelSublist(
leading: new Icon(icon: Icons.star),

30
packages/flutter/lib/src/material/scaffold.dart
View file

@ -50,9 +50,10 @@ enum _ScaffoldSlot {
}
class _ScaffoldLayout extends MultiChildLayoutDelegate {
_ScaffoldLayout({ this.padding });
_ScaffoldLayout({ this.padding, this.appBarBehavior: AppBarBehavior.anchor });
final EdgeInsets padding;
final AppBarBehavior appBarBehavior;
@override
void performLayout(Size size) {
@ -68,7 +69,9 @@ class _ScaffoldLayout extends MultiChildLayoutDelegate {
double contentBottom = size.height - padding.bottom;
if (hasChild(_ScaffoldSlot.appBar)) {
contentTop = layoutChild(_ScaffoldSlot.appBar, fullWidthConstraints).height;
final double appBarHeight = layoutChild(_ScaffoldSlot.appBar, fullWidthConstraints).height;
if (appBarBehavior == AppBarBehavior.anchor)
contentTop = appBarHeight;
positionChild(_ScaffoldSlot.appBar, Offset.zero);
}
@ -522,6 +525,8 @@ class ScaffoldState extends State<Scaffold> {
constraints: new BoxConstraints(maxHeight: expandedHeight)
);
_addIfNonNull(children, appBar, _ScaffoldSlot.appBar);
} else {
children.add(new LayoutId(child: _buildScrollableAppBar(context), id: _ScaffoldSlot.appBar));
}
// Otherwise the AppBar will be part of a [app bar, body] Stack. See AppBarBehavior.scroll below.
@ -565,21 +570,12 @@ class ScaffoldState extends State<Scaffold> {
if (config.appBarBehavior != AppBarBehavior.anchor) {
application = new NotificationListener<ScrollNotification>(
onNotification: _handleScrollNotification,
child: new Stack(
children: <Widget> [
new CustomMultiChildLayout(
children: children,
delegate: new _ScaffoldLayout(
padding: EdgeInsets.zero
)
),
new Positioned(
top: 0.0,
left: 0.0,
right: 0.0,
child: _buildScrollableAppBar(context)
)
]
child: new CustomMultiChildLayout(
children: children,
delegate: new _ScaffoldLayout(
padding: EdgeInsets.zero,
appBarBehavior: config.appBarBehavior
)
)
);
} else {