flutter-banner

2401_83816794

615人浏览 · 2024-05-06 10:30:05

2401_83816794 · 2024-05-06 10:30:05 发布

//the margin of between indicator items

final double indicatorMargin;

final PageController controller;

//whether cycle rolling

final bool cycleRolling;

//whether auto rolling

final bool autoRolling;

final Curve curve;

final ValueChanged onPageChanged;

final bool log;

BannerView(this.banners, {

Key key,

this.initIndex = 0,

this.intervalDuration = const Duration(seconds: 1),

this.animationDuration = const Duration(milliseconds: 500),

this.indicatorBuilder,

this.indicatorNormal,

this.indicatorSelected,

this.indicatorMargin = 5.0,

this.controller,

this.cycleRolling = true,

this.autoRolling = true,

this.curve = Curves.easeInOut,

this.onPageChanged,

this.log = true,

}):

assert(banners?.isNotEmpty ?? true),

assert(null != indicatorMargin),

assert(null != intervalDuration),

assert(null != animationDuration),

assert(null != cycleRolling),

super(key: key);

@override

_BannerViewState createState() => new _BannerViewState();

}

/// Created by yangxiaowei

class _BannerViewState extends State {

List _originBanners = [];

List _banners = [];

Duration _duration;

PageController _pageController;

int _currentIndex = 0;

@override

void initState() {

super.initState();

_Logger.debug = widget.log ?? true;

this._isActive = true;

this._originBanners = widget.banners;

this._banners = this._banners…addAll(this._originBanners);

if(widget.cycleRolling) {

Widget first = this._originBanners[0];

Widget last = this._originBanners[this._originBanners.length - 1];

this._banners.insert(0, last);

this._banners.add(first);

this._currentIndex = widget.initIndex + 1;

}else {

this._currentIndex = widget.initIndex;

}

this._duration = widget.intervalDuration;

this._pageController = widget.controller ?? PageController(initialPage: this._currentIndex);

this._nextBannerTask();

}

Timer _timer;

void _nextBannerTaskBy({int milliseconds = 0}) {

if(!mounted) {

return;

}

if(!widget.autoRolling) {

return;

}

this._cancel();

_timer = new Timer(new Duration(milliseconds: _duration.inMilliseconds + milliseconds), () {

this._doChangeIndex();

});

}

void _nextBannerTask() {

this._nextBannerTaskBy(milliseconds: 0);

}

void _cancel() {

_timer?.cancel();

}

void _doChangeIndex({bool increment = true}) {

if(!mounted) {

return;

}

if(increment) {

this._currentIndex++;

}else{

this._currentIndex–;

}

this._currentIndex = this._currentIndex % this._banners.length;

_Logger.d(TAG, “_doChangeIndex $_currentIndex .”);

if(0 == this._currentIndex) {

this._pageController.jumpToPage(this._currentIndex + 1);

this._nextBannerTaskBy(milliseconds: -_duration.inMilliseconds);

setState(() {});

}else{

this._pageController.animateToPage(

this._currentIndex,

duration: widget.animationDuration,

curve: widget.curve,

);

}

@override

Widget build(BuildContext context) {

return this._generateBody();

}

/// compose the body, banner view and indicator view

Widget _generateBody() {

return new Stack(

children: [

this._renderBannerBody(),

this._renderIndicator(),

);

}

/// Banner container

Widget _renderBannerBody() {

Widget pageView = new PageView.builder(

itemBuilder: (context, index) {

Widget widget = this._banners[index];

return new GestureDetector(

child: widget,

);

controller: this._pageController,

itemCount: this._banners.length,

onPageChanged: (index) {

_Logger.d(TAG, ‘********** changed index: $index cu: $_currentIndex’);

this._currentIndex = index;

this._nextBannerTask();

setState(() {});

if(null != widget.onPageChanged) {

widget.onPageChanged(index);

}

physics: new ClampingScrollPhysics(),

);

// return pageView;

return new NotificationListener(

child: pageView,

onNotification: (notification) {

this._handleScrollNotification(notification);

return true;

);

}

void _handleScrollNotification(Notification notification) {

void _resetWhenAtEdge(PageMetrics pm) {

if(null == pm || !pm.atEdge) {

return;

}

if(!widget.cycleRolling) {

return;

}

try{

if(this._currentIndex == 0) {

this._pageController.jumpToPage(this._banners.length - 2);

}else if(this._currentIndex == this._banners.length - 1) {

this._pageController.jumpToPage(1);

}

setState(() {});

}catch (e){

_Logger.d(TAG, ‘Exception: ${e?.toString()}’);

}

void _handleUserScroll(UserScrollNotification notification) {

UserScrollNotification sn = notification;

PageMetrics pm = sn.metrics;

var page = pm.page;

var depth = sn.depth;

var left = page == .0 ? .0 : page % (page.round());

if(depth == 0) {

_Logger.d(TAG, ‘** page: $page , left: $left , atEdge: ${pm.atEdge} , index: $_currentIndex’);

if(left == 0) {

setState(() {

_resetWhenAtEdge(pm);

});

}

if(notification is UserScrollNotification) {

if(_isStartByUser) {

return;

}

if(_isEndByUser) {

_isEndByUser = false;

}else {

_Logger.d(TAG, ‘######### 手动开始’);

_isStartByUser = true;

this._cancel();

}

_handleUserScroll(notification);

}else if(notification is ScrollEndNotification) {

_Logger.d(TAG, ‘######### ${notification.runtimeType} $_isStartByUser’);

if(_isEndByUser) {

return;

}

if(_isStartByUser) {

_Logger.d(TAG, ‘######### 手动结束’);

_isEndByUser = true;

_isStartByUser = false;

} else {

_isEndByUser = false;

}

this._nextBannerTask();

}

bool _isEndByUser = false;

bool _isStartByUser = false;

/// indicator widget

Widget _renderIndicator() {

int index = widget.cycleRolling ? this._currentIndex - 1 : this._currentIndex;

index = index <= 0 ? 0 : index;

index = index % _originBanners.length;

return new IndicatorWidget(

size: this._originBanners.length,

currentIndex: index,

indicatorBuilder: this.widget.indicatorBuilder,

indicatorNormal: this.widget.indicatorNormal,

indicatorSelected: this.widget.indicatorSelected,

indicatorMargin: this.widget.indicatorMargin,

);

}

bool _isActive = true;

@override

void deactivate() {

super.deactivate();

_isActive = !_isActive;

if(_isActive) {

_nextBannerTask();

} else {

_cancel();

}

@override

void dispose() {

_isActive = false;

_pageController?.dispose();

_cancel();

super.dispose();

}

class _Logger {

static bool debug = true;

static void d(String tag, String msg) {

if(debug) {

print(‘$tag - $msg’);

}

IndicatorWidget.dart

import ‘package:flutter/material.dart’;

import ‘…/banner_view.dart’;

import ‘IndicatorUtil.dart’;

//Created by yangxiaowei at 2018/06/06

//indicator view of banner

class IndicatorWidget extends StatelessWidget {

final IndicatorContainerBuilder indicatorBuilder;

final Widget indicatorNormal;

final Widget indicatorSelected;

final double indicatorMargin;

final int size;

final int currentIndex;

IndicatorWidget({

Key key,

this.size,

this.currentIndex,

this.indicatorBuilder,

this.indicatorNormal,

this.indicatorSelected,

this.indicatorMargin = 5.0,

}):

assert(indicatorMargin != null),

assert(size != null && size > 0),

assert(currentIndex != null && currentIndex >= 0),

super(key: key);

@override

Widget build(BuildContext context) {

return this._renderIndicator(context);

}

//indicator container

Widget _renderIndicator(BuildContext context) {

Widget smallContainer = new Container(

// color: Colors.purple[100],

child: new Row(

mainAxisSize: MainAxisSize.min,

children: _renderIndicatorTag(),

);

if(null != this.indicatorBuilder) {

return this.indicatorBuilder(context, smallContainer);

}

//default implement

return new Align(

alignment: Alignment.bottomCenter,

child: new Opacity(

opacity: 0.5,

child: new Container(

height: 40.0,

padding: new EdgeInsets.symmetric(horizontal: 16.0),

color: Colors.black45,

alignment: Alignment.centerRight,

child: smallContainer,

);

}

//generate every indicator item

List _renderIndicatorTag() {

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List _renderIndicatorTag() {