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Convert ShrineHome to use CustomScrollView (#7887)

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This patch converts the Shrine home page to using a sliver-based grid.
This required using a CustomScrollView to mix the block at the top with
the grid below.
This commit is contained in:
Adam Barth 2017-02-04 16:43:02 -08:00 committed by GitHub
parent 921c0fa5e4
commit 0bcecef5de
2 changed files with 147 additions and 94 deletions
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231
examples/flutter_gallery/lib/demo/shrine/shrine_home.dart
View File

@ -5,6 +5,8 @@
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:meta/meta.dart';
import 'shrine_data.dart';
import 'shrine_order.dart';
@ -17,46 +19,99 @@ const double unitSize = kToolbarHeight;
final List<Product> _products = new List<Product>.from(allProducts());
final Map<Product, Order> _shoppingCart = <Product, Order>{};
const int _childrenPerBlock = 8;
const int _rowsPerBlock = 5;
int _minIndexInRow(int rowIndex) {
final int blockIndex = rowIndex ~/ _rowsPerBlock;
return const <int>[0, 2, 4, 6, 7][rowIndex % _rowsPerBlock] + blockIndex * _childrenPerBlock;
}
int _maxIndexInRow(int rowIndex) {
final int blockIndex = rowIndex ~/ _rowsPerBlock;
return const <int>[1, 3, 5, 6, 7][rowIndex % _rowsPerBlock] + blockIndex * _childrenPerBlock;
}
int _rowAtIndex(int index) {
final int blockCount = index ~/ _childrenPerBlock;
return const <int>[0, 0, 1, 1, 2, 2, 3, 4][index - blockCount * _childrenPerBlock] + blockCount * _rowsPerBlock;
}
int _columnAtIndex(int index) {
return const <int>[0, 1, 0, 1, 0, 1, 0, 0][index % _childrenPerBlock];
}
int _columnSpanAtIndex(int index) {
return const <int>[1, 1, 1, 1, 1, 1, 2, 2][index % _childrenPerBlock];
}
// The Shrine home page arranges the product cards into two columns. The card
// on every 4th and 5th row spans two columns.
class ShrineGridDelegate extends GridDelegate {
int _rowAtIndex(int index) {
final int n = index ~/ 8;
return const <int>[0, 0, 1, 1, 2, 2, 3, 4][index - n * 8] + n * 5;
}
class ShrineGridLayout extends SliverGridLayout {
const ShrineGridLayout({
@required this.rowStride,
@required this.columnStride,
@required this.tileHeight,
@required this.tileWidth,
});
int _columnAtIndex(int index) {
return const <int>[0, 1, 0, 1, 0, 1, 0, 0][index % 8];
}
final double rowStride;
final double columnStride;
final double tileHeight;
final double tileWidth;
int _columnSpanAtIndex(int index) {
return const <int>[1, 1, 1, 1, 1, 1, 2, 2][index % 8];
@override
int getMinChildIndexForScrollOffset(double scrollOffset) {
return _minIndexInRow(scrollOffset ~/ rowStride);
}
@override
GridSpecification getGridSpecification(BoxConstraints constraints, int childCount) {
assert(childCount >= 0);
return new GridSpecification.fromRegularTiles(
tileWidth: constraints.maxWidth / 2.0 - 8.0,
// height = ProductPriceItem + product image + VendorItem
tileHeight: 40.0 + 144.0 + 40.0,
columnCount: 2,
rowCount: childCount == 0 ? 0 : _rowAtIndex(childCount - 1) + 1,
rowSpacing: 8.0,
columnSpacing: 8.0
int getMaxChildIndexForScrollOffset(double scrollOffset) {
return _maxIndexInRow(scrollOffset ~/ rowStride);
}
@override
SliverGridGeometry getGeometryForChildIndex(int index) {
final int row = _rowAtIndex(index);
final int column = _columnAtIndex(index);
final int columnSpan = _columnSpanAtIndex(index);
return new SliverGridGeometry(
scrollOffset: row * rowStride,
crossAxisOffset: column * columnStride,
mainAxisExtent: tileHeight,
crossAxisExtent: tileWidth + (columnSpan - 1) * columnStride,
);
}
@override
GridChildPlacement getChildPlacement(GridSpecification specification, int index, Object placementData) {
assert(index >= 0);
return new GridChildPlacement(
column: _columnAtIndex(index),
row: _rowAtIndex(index),
columnSpan: _columnSpanAtIndex(index),
rowSpan: 1
double estimateMaxScrollOffset(int childCount) {
if (childCount == null)
return null;
if (childCount == 0)
return 0.0;
final int rowCount = _rowAtIndex(childCount - 1) + 1;
final double rowSpacing = rowStride - tileHeight;
return rowStride * rowCount - rowSpacing;
}
}
class ShrineGridDelegate extends SliverGridDelegate {
static const double _kSpacing = 8.0;
@override
SliverGridLayout getLayout(SliverConstraints constraints) {
final double tileWidth = (constraints.crossAxisExtent - _kSpacing) / 2.0;
final double tileHeight = 40.0 + 144.0 + 40.0;
return new ShrineGridLayout(
tileWidth: tileWidth,
tileHeight: tileHeight,
rowStride: tileHeight + _kSpacing,
columnStride: tileWidth + _kSpacing,
);
}
@override
bool shouldRelayout(@checked SliverGridDelegate oldDelegate) => false;
}
/// Displays the Vendor's name and avatar.
@ -77,15 +132,15 @@ class VendorItem extends StatelessWidget {
width: 24.0,
child: new ClipRRect(
borderRadius: new BorderRadius.circular(12.0),
child: new Image.asset(vendor.avatarAsset, fit: ImageFit.cover)
)
child: new Image.asset(vendor.avatarAsset, fit: ImageFit.cover),
),
),
new SizedBox(width: 8.0),
new Expanded(
child: new Text(vendor.name, style: ShrineTheme.of(context).vendorItemStyle)
)
]
)
child: new Text(vendor.name, style: ShrineTheme.of(context).vendorItemStyle),
),
],
),
);
}
}
@ -107,7 +162,7 @@ abstract class PriceItem extends StatelessWidget {
return new Container(
padding: padding,
decoration: decoration,
child: new Text(product.priceString, style: style)
child: new Text(product.priceString, style: style),
);
}
}
@ -120,7 +175,7 @@ class ProductPriceItem extends PriceItem {
return buildItem(
context,
ShrineTheme.of(context).priceStyle,
const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0)
const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
);
}
}
@ -133,7 +188,7 @@ class FeaturePriceItem extends PriceItem {
return buildItem(
context,
ShrineTheme.of(context).featurePriceStyle,
const EdgeInsets.symmetric(horizontal: 24.0, vertical: 16.0)
const EdgeInsets.symmetric(horizontal: 24.0, vertical: 16.0),
);
}
}
@ -180,7 +235,7 @@ class FeatureItem extends StatelessWidget {
child: new Container(
decoration: new BoxDecoration(
backgroundColor: theme.cardBackgroundColor,
border: new Border(bottom: new BorderSide(color: theme.dividerColor))
border: new Border(bottom: new BorderSide(color: theme.dividerColor)),
),
child: new Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
@ -189,8 +244,8 @@ class FeatureItem extends StatelessWidget {
height: unitSize,
child: new Align(
alignment: FractionalOffset.topRight,
child: new FeaturePriceItem(product: product)
)
child: new FeaturePriceItem(product: product),
),
),
new Expanded(
child: new CustomMultiChildLayout(
@ -205,9 +260,9 @@ class FeatureItem extends StatelessWidget {
minHeight: 340.0,
maxHeight: 340.0,
alignment: FractionalOffset.topRight,
child: new Image.asset(product.imageAsset, fit: ImageFit.cover)
)
)
child: new Image.asset(product.imageAsset, fit: ImageFit.cover),
),
),
),
new LayoutId(
id: FeatureLayout.right,
@ -218,23 +273,23 @@ class FeatureItem extends StatelessWidget {
children: <Widget>[
new Padding(
padding: const EdgeInsets.only(top: 18.0),
child: new Text(product.featureTitle, style: theme.featureTitleStyle)
child: new Text(product.featureTitle, style: theme.featureTitleStyle),
),
new Padding(
padding: const EdgeInsets.symmetric(vertical: 16.0),
child: new Text(product.featureDescription, style: theme.featureStyle)
child: new Text(product.featureDescription, style: theme.featureStyle),
),
new VendorItem(vendor: product.vendor)
]
)
)
)
]
)
)
]
)
)
new VendorItem(vendor: product.vendor),
],
),
),
),
],
),
),
],
),
),
);
}
}
@ -257,7 +312,7 @@ class ProductItem extends StatelessWidget {
children: <Widget>[
new Align(
alignment: FractionalOffset.centerRight,
child: new ProductPriceItem(product: product)
child: new ProductPriceItem(product: product),
),
new Container(
width: 144.0,
@ -265,21 +320,21 @@ class ProductItem extends StatelessWidget {
padding: const EdgeInsets.symmetric(horizontal: 8.0),
child: new Hero(
tag: product.tag,
child: new Image.asset(product.imageAsset, fit: ImageFit.contain)
)
child: new Image.asset(product.imageAsset, fit: ImageFit.contain),
),
),
new Padding(
padding: const EdgeInsets.symmetric(horizontal: 8.0),
child: new VendorItem(vendor: product.vendor)
)
]
child: new VendorItem(vendor: product.vendor),
),
],
),
new Material(
type: MaterialType.transparency,
child: new InkWell(onTap: onPressed)
child: new InkWell(onTap: onPressed),
),
]
)
],
),
);
}
}
@ -293,7 +348,7 @@ class ShrineHome extends StatefulWidget {
class _ShrineHomeState extends State<ShrineHome> {
static final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>(debugLabel: 'Shrine Home');
static final GridDelegate gridDelegate = new ShrineGridDelegate();
static final ShrineGridDelegate gridDelegate = new ShrineGridDelegate();
Future<Null> showOrderPage(Product product) async {
final Order order = _shoppingCart[product] ?? new Order(product: product);
@ -303,7 +358,7 @@ class _ShrineHomeState extends State<ShrineHome> {
return new OrderPage(
order: order,
products: _products,
shoppingCart: _shoppingCart
shoppingCart: _shoppingCart,
);
}
));
@ -319,29 +374,27 @@ class _ShrineHomeState extends State<ShrineHome> {
scaffoldKey: scaffoldKey,
products: _products,
shoppingCart: _shoppingCart,
body: new ScrollableViewport(
child: new RepaintBoundary(
child: new Column(
children: <Widget>[
new FeatureItem(product: featured),
new Padding(
padding: const EdgeInsets.all(16.0),
child: new CustomGrid(
delegate: gridDelegate,
children: _products.map((Product product) {
return new RepaintBoundary(
child: new ProductItem(
product: product,
onPressed: () { showOrderPage(product); }
)
);
}).toList()
)
)
]
)
)
)
body: new CustomScrollView(
slivers: <Widget>[
new SliverToBoxAdapter(
child: new FeatureItem(product: featured),
),
new SliverPadding(
padding: const EdgeInsets.all(16.0),
child: new SliverGrid(
gridDelegate: gridDelegate,
delegate: new SliverChildListDelegate(
_products.map((Product product) {
return new ProductItem(
product: product,
onPressed: () { showOrderPage(product); },
);
}).toList(),
),
),
),
],
),
);
}
}

10
packages/flutter/lib/src/rendering/sliver_grid.dart
View File

@ -24,10 +24,10 @@ import 'sliver_multi_box_adaptor.dart';
class SliverGridGeometry {
/// Creates an object that describes the placement of a child in a [RenderSliverGrid].
const SliverGridGeometry({
this.scrollOffset,
this.crossAxisOffset,
this.mainAxisExtent,
this.crossAxisExtent,
@required this.scrollOffset,
@required this.crossAxisOffset,
@required this.mainAxisExtent,
@required this.crossAxisExtent,
});
/// The scroll offset of the leading edge of the child relative to the leading
@ -195,7 +195,7 @@ class SliverGridRegularTileLayout extends SliverGridLayout {
double estimateMaxScrollOffset(int childCount) {
if (childCount == null)
return null;
final int mainAxisCount = ((childCount - 1) / crossAxisCount).floor() + 1;
final int mainAxisCount = ((childCount - 1) ~/ crossAxisCount) + 1;
final double mainAxisSpacing = mainAxisStride - childMainAxisExtent;
return mainAxisStride * mainAxisCount - mainAxisSpacing;
}