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Description:

widgets visibility provider

widgets_visibility_provider #

A library that listens to children inside scrollview
一个监听 scrollview 内部 child 的库

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Getting Started #
widgets_visibility_provider: ^2.0.2
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More info #
Flutter 如何在 scrollview 监听子 widget
Flutter 实现类似 ins 的显示评论框效果
How to use #
如何使用
First #
Use WidgetsVisibilityProvider to wrap scrollview(CustomScrollView, ListView...)
使用 WidgetsVisibilityProvider 包裹 scrollview(CustomScrollview, ListView..)
WidgetsVisibilityProvider(
// range condition default or return null condition is:
// 范围判断默认或者返回 null 情况下执行的是：
// positionData.endPosition >= 0 && positionData.startPosition <= positionData.viewportSize
condition: (PositionData positionData)=> null,
// No need to wrap directly
// 不必直接包裹
child: SomeWidget(
child: ListView.builder(// CustomScrollView, GridView...
...some code...
),
),
)
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Second #
Use VisibleNotifierWidget to wrap child widget
使用 VisibleNotifierWidget 包裹子 widget
on ListView:
ListView.builder(
itemCount: itemCount,
itemBuilder: (context, index) => VisibleNotifierWidget(
// data type is dynamic, you can set everything or don't set or null
// data 的类型是 dynamic, 你可以设置任何数据或者为 null 或者不设置
data: index,
// you can use builder or child
// 你可以使用 builder 或者 child
// positionData and notification is nullable
// positionData 和 notification 有可能为空
builder: (context, notification, positionData) => ...,
// if you use builder, can't use listener and child
// 如果你使用了 builder, 就不能使用 listener 和 child
listener: (context, notification, positionData) {
...
},
child: child(),
// default buildWhen or return null condition is:
// 默认判断或者返回 null 情况下执行的是:
// if (previousPositionData != currentPositionData) return true;
// if (previousPositionData != null && currentPositionData != null)
// return previousNotification != currentNotification;
// return false;
condition: (
previousNotification,
previousPositionData,
currentNotification,
currentPositionData,
)=>...,
),
)
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on SliverToBoxAdapter
SliverToBoxAdapter(
child: VisibleNotifierWidget(
// same to ListView example
// 和上面一样
...
child: child,
),
)
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on SliverList
SliverList(
delegate: SliverChildBuilderDelegate(
(BuildContext context, int index) => VisibleNotifierWidget(
// same to ListView example
// 和上面一样
...
child: child,
),
),
)
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Maybe Third #
If you want to watch all widget information
如果你希望一次过获取所有范围内的 widget 信息
Use WidgetsVisibilityBuilder or WidgetsVisibilityListener or WidgetsVisibilityConsumer in WidgetsVisibilityProvider childtree
If you use bloc, you can also use WidgetsVisibilityProviderBloc
在 WidgetsVisibilityProvider 的子 widget 使用 WidgetsVisibilityBuilder 或者 WidgetsVisibilityListener或者WidgetsVisibilityConsumer
如果你使用 bloc，也可以使用 WidgetsVisibilityProviderBloc
WidgetsVisibilityBuilder(
builder: (context, event) => someWidget,
// Of course, you can also increase the judgment buildWhen
// 当然你也可以增加条件
buildWhen: (previous, current)=>...,
)

WidgetsVisibilityListener(
// Of course, you can also increase the judgment listenWhen
// 当然你也可以增加条件
listenWhen: (previous, current)=>...,
listener: (context, event) {
...
},
child: child,
)

WidgetsVisibilityConsumer(
builder: (context, event) => someWidget,
buildWhen: (previous, current)=>...,
listenWhen: (previous, current)=>...,
listener: (context, event) {
)
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About data bean
PositionData
class PositionData extends Equatable {
final double startPosition;
final double endPosition;
final double viewportSize;
final dynamic data;

...other code
}
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WidgetsVisibilityEvent
class WidgetsVisibilityEvent extends Equatable {
final ScrollNotification notification;
final List<PositionData> positionDataList;

...other code
}
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