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class AdPictureWidget extends StatefulWidget {
 @override
 _AdPictureWidgetState createState() => _AdPictureWidgetState();
}

class _AdPictureWidgetState extends State{
 @override
 Widget build(BuildContext context) {
  return Stack(
   children: [
    ...
   ],
  );
 }
}

class _AdPictureWidgetState extends State{
 PageController _pageController = PageController();
 List _adPictures = [];
 @override
 void dispose() {
  _pageController.dispose();
  super.dispose();
 }
 @override
 Widget build(BuildContext context) {
  return Stack(
   children: [
    PageView(
     children: _adPictures.map((json) {
      var adPicture = AdPicture.fromJson(json);//可以先忽略這個實體類
      return Image.network(
       adPicture.imageUrl,
       fit: BoxFit.fill,//使照片占滿整個屏幕
      );
     }).toList(),
     onPageChanged: _onPageChanged,
     controller: _pageController,
    ),
   ],
  );
 }
 
 void _onPageChanged(int index) {
  ...
 }
}

class _AdPictureWidgetState extends State
  with SingleTickerProviderStateMixin {
 TabController _tabController;
 ...
 @override
 void initState() {
  _tabController = TabController(length: 0, vsync: this);
  super.initState();
 }
 @override
 void dispose() {
  ...
  _tabController.dispose();
  super.dispose();
 }
 @override
 Widget build(BuildContext context) {
  return Stack(
   children: [
    PageView(
     ...
    ),
    Align(
     alignment: Alignment(0.0, 0.5),
     child: TabPageSelector(
      color: Colors.white,
      selectedColor: Colors.black,
      controller: _tabController,
     ),
    ),
   ],
  );
 }

const timeout = const Duration(seconds: 2);
class _AdPictureWidgetState extends State
  with SingleTickerProviderStateMixin {
 ...
 Timer _timer;
 int _index = 0;
 @override
 void initState() {
  ...
  _timer = Timer.periodic(timeout, _handleTimeout);//一創(chuàng)建定時器就啟動了，每過timeout時間就會調(diào)用_handleTimeout這個回調(diào)。
  super.initState();
 }
 @override
 void dispose() {
  ...
  _timer.cancel();
  super.dispose();
 }
 _handleTimeout(Timer timer) {
   _index++;
   _pageController.animateToPage(
    _index % (_adPictures.length),//跳轉(zhuǎn)到的位置
    duration: Duration(milliseconds: 16),//跳轉(zhuǎn)的間隔時間
    curve: Curves.fastOutSlowIn,//跳轉(zhuǎn)動畫
   );
   _tabController.animateTo(_index % (_adPictures.length));
 }

///文件名：AdPictureWidget.dart
class AdPictureWidget extends StatefulWidget {
 @override
 _AdPictureWidgetState createState() => _AdPictureWidgetState();
}
const timeout = const Duration(seconds: 2);
class _AdPictureWidgetState extends State
  with SingleTickerProviderStateMixin {
 TabController _tabController;
 PageController _pageController = PageController();
 Timer _timer;
 List _adPictures = [];
 int _index = 0;
 @override
 void initState() {
  _tabController = TabController(length: 0, vsync: this);
  _timer = Timer.periodic(timeout, _handleTimeout);
  loadAdPictures();
  super.initState();
 }
 @override
 void dispose() {
  _tabController.dispose();
  _timer.cancel();
  _pageController.dispose();
  super.dispose();
 }
 @override
 Widget build(BuildContext context) {
  return Stack(
   children: [
    PageView(
     children: _adPictures.map((json) {
      var adPicture = AdPicture.fromJson(json);
      return Image.network(adPicture.imageUrl, fit: BoxFit.fill);
     }).toList(),
     onPageChanged: _onPageChanged,
     controller: _pageController,
    ),
    Align(
     alignment: Alignment(0.0, 0.5),
     child: TabPageSelector(
      color: Colors.white,
      selectedColor: Colors.black,
      controller: _tabController,
     ),
    ),
   ],
  );
 }
 _handleTimeout(Timer timer) {
  if (_adPictures.length - 2 != 0) {
   _index++;
   _pageController.animateToPage(
    _index % (_adPictures.length - 2),
    duration: Duration(milliseconds: 16),
    curve: Curves.fastOutSlowIn,
   );
  }
 }
 void _onPageChanged(int index) {
  _index = index;
  if (index == 0) {
   _tabController.animateTo(_tabController.length - 1);
   _pageController.jumpToPage(_adPictures.length - 2);
  } else if (index == _adPictures.length - 1) {
   _tabController.animateTo(0);
   _pageController.jumpToPage(1);
  } else {
   _tabController.animateTo(index - 1);
  }
 }
 void loadAdPictures() async {
  Dio dio = Dio();
  Response response = await dio
    .get("http://www.wanandroid.com/tools/mockapi/2511/getAdPictures");
  List res = response.data;
  if (res.length != 0) {
   res.insert(0, res[res.length - 1]);
   res.add(res[1]);
   setState(() {
    _adPictures = res;
    _pageController.jumpToPage(1);
    _tabController =
      TabController(length: _adPictures.length - 2, vsync: this);
   });
  }
 }
}

///文件名：AdPicture.dart
library adpicture;
import 'package:json_annotation/json_annotation.dart';
part 'AdPicture.g.dart';
///首頁輪播圖
@JsonSerializable()
class AdPicture {
 final String imageUrl; //圖片鏈接
 AdPicture({
  this.imageUrl,
 });
 factory AdPicture.fromJson(Map json) =>
   _$AdPictureFromJson(json);
}

///文件名：AdPicture.g.dart
part of adpicture;
AdPicture _$AdPictureFromJson(Map json) {
 return AdPicture(imageUrl: json['imageUrl'] as String);
}

Map _$AdPictureToJson(AdPicture instance) => {
   'imageUrl': instance.imageUrl,
  };