app/lib/widgets/pic_swiper.dart

import 'dart:async';
import 'dart:math';
import 'dart:ui';

import 'package:flutter/material.dart' hide Image;
import 'package:flutter/rendering.dart';

import 'package:extended_image/extended_image.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';

import 'package:recook/constants/header.dart';
import 'package:recook/utils/image_utils.dart';
import 'package:recook/widgets/progress/re_toast.dart';

double initScale({Size imageSize, Size size, double initialScale}) {
  var n1 = imageSize.height / imageSize.width;
  var n2 = size.height / size.width;
  if (n1 > n2) {
    final FittedSizes fittedSizes =
        applyBoxFit(BoxFit.contain, imageSize, size);
    //final Size sourceSize = fittedSizes.source;
    Size destinationSize = fittedSizes.destination;
    return size.width / destinationSize.width;
  } else if (n1 / n2 < 1 / 4) {
    final FittedSizes fittedSizes =
        applyBoxFit(BoxFit.contain, imageSize, size);
    //final Size sourceSize = fittedSizes.source;
    Size destinationSize = fittedSizes.destination;
    return size.height / destinationSize.height;
  }

  return initialScale;
}

class PicSwiper extends StatefulWidget {
  // final int index;
  // final List<PicSwiperItem> pics;
  final Map arguments;
  const PicSwiper({Key key, this.arguments});
  static setArguments({int index, List<PicSwiperItem> pics}) {
    return {"index": index, "pics": pics};
  }

  @override
  _PicSwiperState createState() => _PicSwiperState();
}

class _PicSwiperState extends State<PicSwiper>
    with SingleTickerProviderStateMixin {
  var rebuildIndex = StreamController<int>.broadcast();
  var rebuildSwiper = StreamController<bool>.broadcast();
  AnimationController _animationController;
  Animation<double> _animation;
  Function animationListener;
//  CancellationToken _cancelToken;
//  CancellationToken get cancelToken {
//    if (_cancelToken == null || _cancelToken.isCanceled)
//      _cancelToken = CancellationToken();
//
//    return _cancelToken;
//  }
  List<double> doubleTapScales = <double>[1.0, 2.0];
  GlobalKey<ExtendedImageSlidePageState> slidePagekey =
      GlobalKey<ExtendedImageSlidePageState>();
  int currentIndex;
  bool _showSwiper = true;

  @override
  void initState() {
    currentIndex = widget.arguments["index"];
    _animationController = AnimationController(
        duration: const Duration(milliseconds: 150), vsync: this);
    super.initState();
  }

  @override
  void dispose() {
    rebuildIndex.close();
    rebuildSwiper.close();
    _animationController?.dispose();
    clearGestureDetailsCache();
    //cancelToken?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    var size = MediaQuery.of(context).size;
    Widget result = Material(

        /// if you use ExtendedImageSlidePage and slideType =SlideType.onlyImage,
        /// make sure your page is transparent background
        color: Colors.transparent,
        shadowColor: Colors.transparent,
        child: Stack(
          fit: StackFit.expand,
          children: <Widget>[
            ExtendedImageGesturePageView.builder(
              itemBuilder: (BuildContext context, int index) {
                var item = widget.arguments["pics"][index].picUrl;
                Widget image = ExtendedImage.network(
                  item,
                  fit: BoxFit.contain,
                  enableSlideOutPage: true,
                  mode: ExtendedImageMode.gesture,
                  initGestureConfigHandler: (state) {
                    double initialScale = 1.0;

                    if (state.extendedImageInfo != null &&
                        state.extendedImageInfo.image != null) {
                      initialScale = initScale(
                          size: size,
                          initialScale: initialScale,
                          imageSize: Size(
                              state.extendedImageInfo.image.width.toDouble(),
                              state.extendedImageInfo.image.height.toDouble()));
                    }
                    return GestureConfig(
                        inPageView: true,
                        initialScale: initialScale,
                        maxScale: max(initialScale, 5.0),
                        animationMaxScale: max(initialScale, 5.0),
                        //you can cache gesture state even though page view page change.
                        //remember call clearGestureDetailsCache() method at the right time.(for example,this page dispose)
                        cacheGesture: false);
                  },
                  onDoubleTap: (ExtendedImageGestureState state) {
                    ///you can use define pointerDownPosition as you can,
                    ///default value is double tap pointer down postion.
                    var pointerDownPosition = state.pointerDownPosition;
                    double begin = state.gestureDetails.totalScale;
                    double end;

                    //remove old
                    _animation?.removeListener(animationListener);

                    //stop pre
                    _animationController.stop();

                    //reset to use
                    _animationController.reset();

                    if (begin == doubleTapScales[0]) {
                      end = doubleTapScales[1];
                    } else {
                      end = doubleTapScales[0];
                    }

                    animationListener = () {
                      //print(_animation.value);
                      state.handleDoubleTap(
                          scale: _animation.value,
                          doubleTapPosition: pointerDownPosition);
                    };
                    _animation = _animationController
                        .drive(Tween<double>(begin: begin, end: end));

                    _animation.addListener(animationListener);

                    _animationController.forward();
                  },
                );
                image = GestureDetector(
                  child: image,
                  onTap: () {
                    // slidePagekey.currentState.popPage();
                    Navigator.pop(context);
                  },
                );

                if (index == currentIndex) {
                  return Hero(
                    tag: item + index.toString(),
                    child: image,
                    flightShuttleBuilder: (BuildContext flightContext,
                        Animation<double> animation,
                        HeroFlightDirection flightDirection,
                        BuildContext fromHeroContext,
                        BuildContext toHeroContext) {
                      final Hero hero =
                          flightDirection == HeroFlightDirection.pop
                              ? fromHeroContext.widget
                              : toHeroContext.widget;
                      return hero.child;
                    },
                  );
                } else {
                  return image;
                }
              },
              itemCount: widget.arguments["pics"].length,
              onPageChanged: (int index) {
                currentIndex = index;
                rebuildIndex.add(index);
              },
              controller: PageController(
                initialPage: currentIndex,
              ),
              scrollDirection: Axis.horizontal,
              physics: BouncingScrollPhysics(),
//              //move page only when scale is not more than 1.0
//              canMovePage: (GestureDetails gestureDetails) =>
//                  gestureDetails.totalScale <= 1.0,
              //physics: ClampingScrollPhysics(),
            ),
            StreamBuilder<bool>(
              builder: (c, d) {
                if (d.data == null || !d.data) return Container();

                return Positioned(
                  bottom: 0.0,
                  left: 0.0,
                  right: 0.0,
                  child: MySwiperPlugin(
                    widget.arguments["pics"],
                    currentIndex,
                    rebuildIndex,
                  ),
                );
              },
              initialData: true,
              stream: rebuildSwiper.stream,
            )
          ],
        ));

    result = ExtendedImageSlidePage(
      // key: slidePagekey,
      child: result,
      slideAxis: SlideAxis.both,
      slideType: SlideType.onlyImage,
      onSlidingPage: (state) {
        ///you can change other widgets' state on page as you want
        ///base on offset/isSliding etc
        //var offset= state.offset;
        var showSwiper = !state.isSliding;
        if (showSwiper != _showSwiper) {
          // do not setState directly here, the image state will change,
          // you should only notify the widgets which are needed to change
          // setState(() {
          // _showSwiper = showSwiper;
          // });

          _showSwiper = showSwiper;
          rebuildSwiper.add(_showSwiper);
        }
      },
    );

    return result;
  }
}

class MySwiperPlugin extends StatelessWidget {
  final List<PicSwiperItem> pics;
  final int index;
  final StreamController<int> reBuild;
  MySwiperPlugin(
    this.pics,
    this.index,
    this.reBuild,
  );
  @override
  Widget build(BuildContext context) {
    return StreamBuilder<int>(
      builder: (BuildContext context, data) {
        return DefaultTextStyle(
          style: TextStyle(color: Colors.blue),
          child: Container(
              height: 50.0 + ScreenUtil().bottomBarHeight,
              alignment: Alignment.topCenter,
              width: double.infinity,
              color: Colors.grey.withOpacity(0.2),
              child: Container(
                height: 50.0,
                child: Row(
                  children: _rowContainer(data, context),
                ),
              )),
        );
      },
      initialData: index,
      stream: reBuild.stream,
    );
  }

  _rowContainer(data, context) {
    return <Widget>[
      Container(
        width: 10.0,
      ),
      Text(
        "${data.data + 1}",
      ),
      Text(
        " / ${pics.length}",
      ),
      Expanded(
          child: Text(pics[data.data].des ?? "",
              maxLines: 1,
              overflow: TextOverflow.ellipsis,
              style: TextStyle(fontSize: 16.0, color: Colors.blue))),
      Container(
        width: 10.0,
      ),
      GestureDetector(
        child: Container(
          padding: EdgeInsets.only(right: 10.0),
          alignment: Alignment.center,
          child: Text(
            "保存到本地",
            style: TextStyle(fontSize: 16.0, color: Colors.blue),
          ),
        ),
        onTap: () {
          //GSDialog.of(context).showLoadingDialog(context, "保存图片中...");
         var cancel =  ReToast.loading(text:"保存图片中...");
          List<String> urls = [pics[data.data].picUrl];
          ImageUtils.saveNetworkImagesToPhoto(urls, (index) {
            DPrint.printf("保存好了---${urls[index]}");
            DPrint.printf("保存好了---$index");
          }, (success) {
            cancel();
            //GSDialog.of(context).dismiss(context);
            success?ReToast.success(text: '保存完成！'):ReToast.err(text: '保存失败...');
                // ? GSDialog.of(context).showSuccess(context, "保存完成!")
                // : GSDialog.of(context).showError(context, "保存失败...");

          });
        },
      ),
    ];
  }
}

class PicSwiperItem {
  String picUrl;
  String des;
  PicSwiperItem(this.picUrl, {this.des = ""});
}