flutter-sport/lib/pages/social/gallery_photo_view.dart

import 'dart:typed_data';

import 'package:cached_network_image/cached_network_image.dart';
import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:image_gallery_saver/image_gallery_saver.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:photo_view/photo_view.dart';
import 'package:photo_view/photo_view_gallery.dart';
import 'package:sport/application.dart';
import 'package:sport/bean/image.dart' as photo;
import 'package:sport/utils/toast.dart';
import 'package:sport/widgets/dialog/modal_bottom_action.dart';
import 'package:sport/widgets/dialog/request_dialog.dart';
import 'package:sport/widgets/loading.dart';

void open(BuildContext context, final int index, List<photo.Image> images) {
  Navigator.push(
    context,
    FadeRoute(
      page: GalleryPhotoViewWrapper(
        galleryItems: images,
        backgroundDecoration: const BoxDecoration(
          color: Colors.black,
        ),
        initialIndex: index,
        scrollDirection: Axis.horizontal,
        loadingBuilder: (_, __) => RequestLoadingWidget(),
      ),
    ),
  );
}

class FadeRoute extends PageRouteBuilder {
  final Widget page;

  FadeRoute({this.page})
      : super(
          pageBuilder: (
            BuildContext context,
            Animation<double> animation,
            Animation<double> secondaryAnimation,
          ) =>
              page,
          transitionsBuilder: (
            BuildContext context,
            Animation<double> animation,
            Animation<double> secondaryAnimation,
            Widget child,
          ) =>
              FadeTransition(
            opacity: animation,
            child: child,
          ),
        );
}

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<photo.Image> 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: Stack(
        children: <Widget>[
          Container(
            decoration: widget.backgroundDecoration,
            constraints: BoxConstraints.expand(
              height: MediaQuery.of(context).size.height,
            ),
            child: GestureDetector(
              onLongPress: () async {
                await showActionDialog(context, {
                  "保存至本地": () async {
                    await request(context, () async {
                      var file = await save(widget.galleryItems[currentIndex].src);
                      if (file != null) {
                        ToastUtil.show("已保存图片至：$file");
                      }
                    });
                  }
                });
              },
              child: 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(
              child: SafeArea(
            child: IconButton(
              icon: Image.asset("lib/assets/img/topbar_return_white.png"),
              onPressed: () {
                Navigator.maybePop(context);
              },
            ),
          ))
        ],
      ),
    );
  }

  Future<String> save(String url) async {
    var permission = await Application.requestPermission(Permission.storage);
    if (!permission) {
      ToastUtil.show("没有相应权限！");
      return null;
    }
    var response = await Dio().get(url, options: Options(responseType: ResponseType.bytes));
    final result = await ImageGallerySaver.saveImage(Uint8List.fromList(response.data), quality: 100, name: "shoes_${DateTime.now().millisecondsSinceEpoch}");
    print(result);
    return result;
  }

  PhotoViewGalleryPageOptions _buildItem(BuildContext context, int index) {
    final photo.Image item = widget.galleryItems[index];
    return PhotoViewGalleryPageOptions(
        imageProvider: CachedNetworkImageProvider(item.src),
        initialScale: PhotoViewComputedScale.contained,
        minScale: PhotoViewComputedScale.contained * (0.5 + index / 10),
        heroAttributes: PhotoViewHeroAttributes(tag: item.id ?? item.src),
        onTapUp: (
          _,
          __,
          ___,
        ) {
          Navigator.of(context).pop();
        });
  }
}