appear:
git:
url: https://github.com/StanleyCocos/ItemAppear.git
- 创建数据源
class Model extends ItemAppearModel {
int index = 0;
String name = "";
double height = 100;
Model({
required this.index,
required this.name,
this.height = 100,
});
}
- 添加key
return GridView.builder(
gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 3,
mainAxisSpacing: 20.0,
crossAxisSpacing: 10.0,
childAspectRatio: 1.0,
),
itemBuilder: (context, position) {
var model = list[position];
return GestureDetector(
child: Container(
key: model.key,
width: double.infinity,
height: 100,
color: Colors.blue,
child: Center(
child: Text("$position"),
),
),
);
},
itemCount: list.length,
);
}
- 接收回调
ItemAppear(
callback: (list){
// 回调相应完整出现在屏幕的item
list.forEach((element) {
if (element is Model) {
print("${element.index} 出现");
}
});
},
// 数据源
items: list,
// 需要统计的列表
child: flow,
),
- 完整例子
import 'dart:math';
import 'package:appear/appear.dart';
import 'package:flutter/material.dart';
import 'package:waterfall_flow/waterfall_flow.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class Model extends ItemAppearModel {
int index = 0;
String name = "";
double height = 100;
Model({
required this.index,
required this.name,
this.height = 100,
});
}
class _MyHomePageState extends State<MyHomePage> {
List<Model> list = [];
@override
void initState() {
for (int index = 0; index <= 30; index++) {
var model = Model(index: index, name: "${index}", height: Random().nextInt(200).toDouble() + 100);
list.add(model);
}
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Padding(
padding: EdgeInsets.only(
top: 100,
bottom: 200,
),
child: ItemAppear(
// 是否可以重复统计
repeat: false,
// 回调相应完整出现在屏幕的item
callback: (list){
list.forEach((element) {
if (element is Model) {
print("${element.index} 出现");
}
});
},
// 数据源
items: list,
// 需要统计的列表
child: flow,
),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
Widget get grid {
return GridView.builder(
gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 3,
mainAxisSpacing: 20.0,
crossAxisSpacing: 10.0,
childAspectRatio: 1.0,
),
itemBuilder: (context, position) {
var model = list[position];
return GestureDetector(
child: Container(
key: model.key,
width: double.infinity,
height: 100,
color: Colors.blue,
child: Center(
child: Text("$position"),
),
),
);
},
itemCount: list.length,
);
}
Widget get flow {
return CustomScrollView(
slivers: [
SliverToBoxAdapter(
child: Container(
width: double.infinity,
height: 200,
color: Colors.grey,
),
),
SliverToBoxAdapter(
child: Container(
width: double.infinity,
// height: 200,
color: Colors.lightGreen,
child: Row(
children: [
Expanded(
flex: 1,
child: Column(
children: [
Container(
width: double.infinity,
height: 80,
color: Colors.green,
),
Center(
child: const Text("入口1"),
),
],
),
),
Expanded(
flex: 1,
child: Column(
children: [
Container(
width: double.infinity,
height: 80,
color: Colors.orangeAccent,
),
Center(
child: const Text("入口1"),
),
],
),
),
Expanded(
flex: 1,
child: Column(
children: [
Container(
width: double.infinity,
height: 80,
color: Colors.redAccent,
),
Center(
child: const Text("入口1"),
),
],
),
),
Expanded(
flex: 1,
child: Column(
children: [
Container(
width: double.infinity,
height: 80,
color: Colors.indigo,
),
Center(
child: const Text("入口1"),
),
],
),
),
],
),
),
),
SliverPadding(
padding: EdgeInsets.only(
left: 16,
right: 16,
top: 16,
),
sliver: SliverWaterfallFlow.count(
crossAxisCount: 2,
crossAxisSpacing: 16,
mainAxisSpacing: 16,
children: listItem,
// viewportBuilder: viewportBuilder,
),
)
],
);
}
List<Widget> get listItem {
List<Widget> array = [];
list.forEach((element) {
array.add(FlowItemWidget(element));
});
return array;
}
}
class FlowItemWidget extends StatelessWidget {
Model model;
FlowItemWidget(this.model);
@override
Widget build(BuildContext context) {
return Container(
key: model.key,
width: double.infinity,
height: model.height,
color: rdColor,
child: Center(
child: Text("${model.index}"),
),
);
}
}
Color get rdColor => Color.fromRGBO(Random().nextInt(256), Random().nextInt(256), Random().nextInt(256), 1);