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Description:

waterfall flow

waterfall_flow #

A Flutter grid view easy to build waterfall flow layout quickly.
Web demo for WaterfallFlow
Language: English | 中文简体

waterfall_flow

Use
Easy to use
CollectGarbage
ViewportBuilder
LastChildLayoutTypeBuilder
CloseToTrailing

Use #

add library to your pubspec.yaml

dependencies:
waterfall_flow: any

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import library in dart file

import 'package:waterfall_flow/waterfall_flow.dart';

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Easy to use #

you can define waterfall flow layout within SliverWaterfallFlowDelegate.

SliverWaterfallFlowDelegateWithFixedCrossAxisCount

parameter
description
default

crossAxisCount
The number of children in the cross axis.
required

SliverWaterfallFlowDelegateWithMaxCrossAxisExtent

parameter
description
default

maxCrossAxisExtent
The maximum extent of tiles in the cross axis.
required

SliverWaterfallFlowDelegate

parameter
description
default

mainAxisSpacing
The number of logical pixels between each child along the main axis.
0.0

crossAxisSpacing
The number of logical pixels between each child along the cross axis.
0.0

collectGarbage
Call when collect garbage, return indexs to collect
-

lastChildLayoutTypeBuilder
The builder to get layout type of last child ,Notice: it should only for last child
-

viewportBuilder
The builder to get indexs in viewport
-

closeToTrailing
Whether make layout close to trailing
false

WaterfallFlow.builder(
//cacheExtent: 0.0,
padding: EdgeInsets.all(5.0),
gridDelegate: SliverWaterfallFlowDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
crossAxisSpacing: 5.0,
mainAxisSpacing: 5.0,
/// follow max child trailing layout offset and layout with full cross axis extend
/// last child as loadmore item/no more item in [GridView] and [WaterfallFlow]
/// with full cross axis extend
// LastChildLayoutType.fullCrossAxisExtend,

/// as foot at trailing and layout with full cross axis extend
/// show no more item at trailing when children are not full of viewport
/// if children is full of viewport, it's the same as fullCrossAxisExtend
// LastChildLayoutType.foot,
lastChildLayoutTypeBuilder: (index) => index == _list.length
? LastChildLayoutType.foot
: LastChildLayoutType.none,
),

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CollectGarbage #
track the indexes are collect, you can collect garbage at that monment(for example Image cache)
more detail
WaterfallFlow.builder(
gridDelegate: SliverWaterfallFlowDelegateWithFixedCrossAxisCount(
collectGarbage: (List<int> garbages) {
///collectGarbage
garbages.forEach((index) {
final provider = ExtendedNetworkImageProvider(
_list[index].imageUrl,
);
provider.evict();
});
},
),
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ViewportBuilder #
track the indexes go into the viewport, it's not include cache extent.
WaterfallFlow.builder(
gridDelegate: SliverWaterfallFlowDelegateWithFixedCrossAxisCount(
viewportBuilder: (int firstIndex, int lastIndex) {
print("viewport : [$firstIndex,$lastIndex]");
}),
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LastChildLayoutTypeBuilder #
build lastChild as special child in the case that it is loadmore/no more item.
enum LastChildLayoutType {
/// as default child
none,

/// follow max child trailing layout offset and layout with full cross axis extend
/// last child as loadmore item/no more item in [ExtendedGridView] and [WaterfallFlow]
/// with full cross axis extend
fullCrossAxisExtend,

/// as foot at trailing and layout with full cross axis extend
/// show no more item at trailing when children are not full of viewport
/// if children is full of viewport, it's the same as fullCrossAxisExtend
foot,
}

WaterfallFlow.builder(
gridDelegate: SliverWaterfallFlowDelegateWithFixedCrossAxisCount(
lastChildLayoutTypeBuilder: (index) => index == length
? LastChildLayoutType.foot
: LastChildLayoutType.none,
),
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CloseToTrailing #
when reverse property of List is true, layout is as following.
it likes chat list, and new session will insert to zero index.
but it's not right when items are not full of viewport.
trailing
-----------------
| |
| |
| item2 |
| item1 |
| item0 |
-----------------
leading
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to solve it, you could set closeToTrailing to true, layout is as following.
support [ExtendedGridView],[ExtendedList],[WaterfallFlow].
and it also works when reverse is flase, layout will close to trailing.
trailing
-----------------
| item2 |
| item1 |
| item0 |
| |
| |
-----------------
leading
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WaterfallFlow.builder(
reverse: true,
gridDelegate: SliverWaterfallFlowDelegateWithFixedCrossAxisCount(closeToTrailing: true),
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