aku_new_community/lib/widget/gallery_photo_view_wrapper.dart

// Flutter imports:
import 'package:flutter/material.dart';

// Package imports:
import 'package:get/get.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:photo_view/photo_view.dart';
import 'package:photo_view/photo_view_gallery.dart';

// Project imports:
import 'cached_image_wrapper.dart';

// import 'package:image_gallery_saver/image_gallery_saver.dart';

class GalleryPhotoViewWrapper extends StatefulWidget {
  GalleryPhotoViewWrapper({
    this.loadingBuilder,
    this.backgroundDecoration,
    this.minScale,
    this.maxScale,
    this.initialIndex,
    @required this.galleryItems,
    this.scrollDirection = Axis.horizontal,
  }) : pageController = PageController(initialPage: initialIndex);

  final LoadingBuilder loadingBuilder;
  final Decoration backgroundDecoration;
  final dynamic minScale;
  final dynamic maxScale;
  final int initialIndex;
  final PageController pageController;
  final List galleryItems;
  final Axis scrollDirection;

  @override
  State<StatefulWidget> createState() {
    return _GalleryPhotoViewWrapperState();
  }
}

class _GalleryPhotoViewWrapperState extends State<GalleryPhotoViewWrapper> {
  int currentIndex;

  @override
  void initState() {
    currentIndex = widget.initialIndex;
    super.initState();
  }

  void onPageChanged(int index) {
    setState(() {
      currentIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        decoration: widget.backgroundDecoration,
        constraints: BoxConstraints.expand(
          height: MediaQuery.of(context).size.height,
        ),
        child: Stack(
          alignment: Alignment.bottomRight,
          children: <Widget>[
            PhotoViewGallery.builder(
              scrollPhysics: const BouncingScrollPhysics(),
              builder: _buildItem,
              itemCount: widget.galleryItems.length,
              loadingBuilder: widget.loadingBuilder,
              backgroundDecoration: widget.backgroundDecoration,
              pageController: widget.pageController,
              onPageChanged: onPageChanged,
              scrollDirection: widget.scrollDirection,
            ),
            Positioned(
              //图片index显示
              top: MediaQuery.of(context).padding.top + 15,
              width: MediaQuery.of(context).size.width,
              child: Center(
                child: Text("${currentIndex + 1}/${widget.galleryItems.length}",
                    style: TextStyle(color: Colors.white, fontSize: 16)),
              ),
            ),
            Positioned(
              //右上角关闭按钮
              right: 10,
              top: MediaQuery.of(context).padding.top,
              child: IconButton(
                icon: Icon(
                  Icons.close,
                  size: 30,
                  color: Colors.white,
                ),
                onPressed: () {
                  Get.back();
                },
              ),
            ),
          ],
        ),
      ),
    );
  }

//动态申请权限，ios 要在info.plist 上面添加
  Future<bool> requestPermission() async {
    var status = await Permission.photos.status;
    if (status.isUndetermined) {
      await [Permission.photos].request();
    }
    return status.isGranted;
  }

  PhotoViewGalleryPageOptions _buildItem(BuildContext context, int index) {
    final GalleryExampleItem item = widget.galleryItems[index];
    return PhotoViewGalleryPageOptions(
      onTapUp: (BuildContext context, TapUpDetails details,
          PhotoViewControllerValue controllerValue) {
        Get.back();
      },
      imageProvider: NetworkImage(item.resource),
//      initialScale: PhotoViewComputedScale.contained,
//      minScale: PhotoViewComputedScale.contained * (0.5 + index / 10),
//      maxScale: PhotoViewComputedScale.covered * 1.1,

      heroAttributes: PhotoViewHeroAttributes(tag: item.id),
    );
  }
}

//Hero 动画组件
// ignore: must_be_immutable
class GalleryExampleItemThumbnail extends StatelessWidget {
  GalleryExampleItemThumbnail({Key key, this.galleryExampleItem, this.onTap})
      : super(key: key);

  final GalleryExampleItem galleryExampleItem;

  final GestureTapCallback onTap;
  UniqueKey uniqueKey = UniqueKey();

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(4),
      ),
      child: GestureDetector(
        onTap: onTap,
        child: Hero(
          tag: uniqueKey,
          child: CachedImageWrapper(
            url: galleryExampleItem.resource,
            height: 15,
            width: 15,
            fit: BoxFit.cover,
          ),
        ),
      ),
    );
  }
}

//model
class GalleryExampleItem {
  GalleryExampleItem({this.id, this.resource, this.isSvg = false});
  //hero的id 不能重复
  String id;
  String resource;
  bool isSvg;
}