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[Gallery] Implement Desktop study carousel (#315)

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pull/316/head
rami-a 5 years ago committed by GitHub
parent cee267cf88
commit dc66d5f998
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1 changed files with 229 additions and 21 deletions
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250
gallery/lib/pages/home.dart
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@ -30,12 +30,13 @@ const _horizontalPadding = 32.0;
const _carouselItemMargin = 8.0;
const _horizontalDesktopPadding = 81.0;
const _carouselHeightMin = 200.0 + 2 * _carouselItemMargin;
const _desktopCardsPerPage = 4;
const shrineTitle = 'Shrine';
const rallyTitle = 'Rally';
const craneTitle = 'Crane';
const homeCategoryMaterial = 'MATERIAL';
const homeCategoryCupertino = 'CUPERTINO';
const _shrineTitle = 'Shrine';
const _rallyTitle = 'Rally';
const _craneTitle = 'Crane';
const _homeCategoryMaterial = 'MATERIAL';
const _homeCategoryCupertino = 'CUPERTINO';
class ToggleSplashNotification extends Notification {}
@ -52,9 +53,9 @@ class HomePage extends StatelessWidget {
Widget build(BuildContext context) {
var carouselHeight = _carouselHeight(.7, context);
final isDesktop = isDisplayDesktop(context);
final carouselCards = <_CarouselCard>[
final carouselCards = <Widget>[
_CarouselCard(
title: shrineTitle,
title: _shrineTitle,
subtitle: GalleryLocalizations.of(context).shrineDescription,
asset: 'assets/studies/shrine_card.png',
assetDark: 'assets/studies/shrine_card_dark.png',
@ -63,7 +64,7 @@ class HomePage extends StatelessWidget {
navigatorKey: NavigatorKeys.shrine,
),
_CarouselCard(
title: rallyTitle,
title: _rallyTitle,
subtitle: GalleryLocalizations.of(context).rallyDescription,
textColor: RallyColors.accountColors[0],
asset: 'assets/studies/rally_card.png',
@ -72,7 +73,7 @@ class HomePage extends StatelessWidget {
navigatorKey: NavigatorKeys.rally,
),
_CarouselCard(
title: craneTitle,
title: _craneTitle,
subtitle: GalleryLocalizations.of(context).craneDescription,
asset: 'assets/studies/crane_card.png',
assetDark: 'assets/studies/crane_card_dark.png',
@ -101,12 +102,12 @@ class HomePage extends StatelessWidget {
if (isDesktop) {
final desktopCategoryItems = <_DesktopCategoryItem>[
_DesktopCategoryItem(
title: homeCategoryMaterial,
title: _homeCategoryMaterial,
imageString: 'assets/icons/material/material.png',
demos: materialDemos(context),
),
_DesktopCategoryItem(
title: homeCategoryCupertino,
title: _homeCategoryCupertino,
imageString: 'assets/icons/cupertino/cupertino.png',
demos: cupertinoDemos(context),
),
@ -120,12 +121,15 @@ class HomePage extends StatelessWidget {
return Scaffold(
body: ListView(
padding: EdgeInsetsDirectional.only(
start: _horizontalDesktopPadding,
top: isDesktop ? firstHeaderDesktopTopPadding : 21,
end: _horizontalDesktopPadding,
),
children: [
ExcludeSemantics(child: _GalleryHeader()),
Padding(
padding: const EdgeInsets.symmetric(
horizontal: _horizontalDesktopPadding,
),
child: ExcludeSemantics(child: _GalleryHeader()),
),
/// TODO: When Focus widget becomes better remove dummy Focus
/// variable.
@ -143,15 +147,19 @@ class HomePage extends StatelessWidget {
),
Container(
height: carouselHeight,
child: Row(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: spaceBetween(30, carouselCards),
child: _DesktopCarousel(children: carouselCards),
),
Padding(
padding: const EdgeInsets.symmetric(
horizontal: _horizontalDesktopPadding,
),
child: _CategoriesHeader(),
),
_CategoriesHeader(),
Container(
height: 585,
padding: const EdgeInsets.symmetric(
horizontal: _horizontalDesktopPadding,
),
child: Row(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
@ -160,7 +168,9 @@ class HomePage extends StatelessWidget {
),
Padding(
padding: const EdgeInsetsDirectional.only(
start: _horizontalDesktopPadding,
bottom: 81,
end: _horizontalDesktopPadding,
top: 109,
),
child: Row(
@ -332,7 +342,7 @@ class _AnimatedHomePageState extends State<_AnimatedHomePage>
startDelayFraction: 0.00,
controller: _animationController,
child: CategoryListItem(
title: homeCategoryMaterial,
title: _homeCategoryMaterial,
imageString: 'assets/icons/material/material.png',
demos: materialDemos(context),
),
@ -341,7 +351,7 @@ class _AnimatedHomePageState extends State<_AnimatedHomePage>
startDelayFraction: 0.05,
controller: _animationController,
child: CategoryListItem(
title: homeCategoryCupertino,
title: _homeCategoryCupertino,
imageString: 'assets/icons/cupertino/cupertino.png',
demos: cupertinoDemos(context),
),
@ -715,6 +725,204 @@ class _CarouselState extends State<_Carousel>
}
}
/// This creates a horizontally scrolling [ListView] of items.
///
/// This class uses a [ListView] with a custom [ScrollPhysics] to enable
/// snapping behavior. A [PageView] was considered but does not allow for
/// multiple pages visible without centering the first page.
class _DesktopCarousel extends StatefulWidget {
const _DesktopCarousel({Key key, this.children}) : super(key: key);
final List<Widget> children;
@override
_DesktopCarouselState createState() => _DesktopCarouselState();
}
class _DesktopCarouselState extends State<_DesktopCarousel> {
static const cardPadding = 15.0;
ScrollController _controller;
@override
void initState() {
super.initState();
_controller = ScrollController();
_controller.addListener(() {
setState(() {});
});
}
@override
dispose() {
_controller.dispose();
super.dispose();
}
Widget _builder(int index) {
return Padding(
padding: const EdgeInsets.symmetric(
vertical: 8,
horizontal: cardPadding,
),
child: widget.children[index],
);
}
@override
Widget build(BuildContext context) {
var showPreviousButton = false;
var showNextButton = true;
// Only check this after the _controller has been attached to the ListView.
if (_controller.hasClients) {
showPreviousButton = _controller.offset > 0;
showNextButton =
_controller.offset < _controller.position.maxScrollExtent;
}
final totalWidth = MediaQuery.of(context).size.width -
(_horizontalDesktopPadding - cardPadding) * 2;
final itemWidth = totalWidth / _desktopCardsPerPage;
return Stack(
children: [
Padding(
padding: const EdgeInsets.symmetric(
horizontal: _horizontalDesktopPadding - cardPadding,
),
child: ListView.builder(
scrollDirection: Axis.horizontal,
physics: _SnappingScrollPhysics(),
controller: _controller,
itemExtent: itemWidth,
itemCount: widget.children.length,
itemBuilder: (context, index) => _builder(index),
),
),
if (showPreviousButton)
_DesktopPageButton(
onTap: () {
_controller.animateTo(
_controller.offset - itemWidth,
duration: Duration(milliseconds: 200),
curve: Curves.easeInOut,
);
},
),
if (showNextButton)
_DesktopPageButton(
isEnd: true,
onTap: () {
_controller.animateTo(
_controller.offset + itemWidth,
duration: Duration(milliseconds: 200),
curve: Curves.easeInOut,
);
},
),
],
);
}
}
/// Scrolling physics that snaps to the new item in the [_DesktopCarousel].
class _SnappingScrollPhysics extends ScrollPhysics {
const _SnappingScrollPhysics({ScrollPhysics parent}) : super(parent: parent);
@override
_SnappingScrollPhysics applyTo(ScrollPhysics ancestor) {
return _SnappingScrollPhysics(parent: buildParent(ancestor));
}
double _getTargetPixels(
ScrollMetrics position,
Tolerance tolerance,
double velocity,
) {
final itemWidth = position.viewportDimension / _desktopCardsPerPage;
double item = position.pixels / itemWidth;
if (velocity < -tolerance.velocity) {
item -= 0.5;
} else if (velocity > tolerance.velocity) {
item += 0.5;
}
return math.min(
item.roundToDouble() * itemWidth,
position.maxScrollExtent,
);
}
@override
Simulation createBallisticSimulation(
ScrollMetrics position,
double velocity,
) {
if ((velocity <= 0.0 && position.pixels <= position.minScrollExtent) ||
(velocity >= 0.0 && position.pixels >= position.maxScrollExtent)) {
return super.createBallisticSimulation(position, velocity);
}
final Tolerance tolerance = this.tolerance;
final double target = _getTargetPixels(position, tolerance, velocity);
if (target != position.pixels) {
return ScrollSpringSimulation(
spring,
position.pixels,
target,
velocity,
tolerance: tolerance,
);
}
return null;
}
@override
bool get allowImplicitScrolling => false;
}
class _DesktopPageButton extends StatelessWidget {
const _DesktopPageButton({
Key key,
this.isEnd = false,
this.onTap,
}) : super(key: key);
final bool isEnd;
final GestureTapCallback onTap;
@override
Widget build(BuildContext context) {
final buttonSize = 58.0;
final padding = _horizontalDesktopPadding - buttonSize / 2;
return Align(
alignment: isEnd
? AlignmentDirectional.centerEnd
: AlignmentDirectional.centerStart,
child: Container(
width: buttonSize,
height: buttonSize,
margin: EdgeInsetsDirectional.only(
start: isEnd ? 0 : padding,
end: isEnd ? padding : 0,
),
child: Tooltip(
message: isEnd
? MaterialLocalizations.of(context).nextPageTooltip
: MaterialLocalizations.of(context).previousPageTooltip,
child: Material(
color: Colors.black.withOpacity(0.5),
shape: CircleBorder(),
clipBehavior: Clip.antiAlias,
child: InkWell(
onTap: onTap,
child: Icon(
isEnd ? Icons.arrow_forward_ios : Icons.arrow_back_ios,
),
),
),
),
),
);
}
}
class _CarouselCard extends StatelessWidget {
const _CarouselCard({
Key key,

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