zefyr/packages/zefyr/lib/src/widgets/gallery_item.dart

import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:photo_manager/photo_manager.dart';

import 'iconfont.dart';
import 'theme.dart';

class GalleryItem extends StatefulWidget {
  const GalleryItem({Key key, this.asset}) : super(key: key);
  final AssetEntity asset;

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

class _GalleryItemState extends State<GalleryItem> {
  final ValueNotifier<bool> _checked = ValueNotifier<bool>(false);
  Uint8List _thumbData;

  @override
  Widget build(BuildContext context) {
    final theme = ZefyrTheme.of(context).toolbarTheme;
    return Stack(
      children: <Widget>[
        GestureDetector(
          behavior: HitTestBehavior.opaque,
          child: Container(
            height: 210,
            margin: EdgeInsets.only(left: 4),
            child: _thumbData != null
                ? Image.memory(
                    _thumbData,
                    fit: BoxFit.cover,
                  )
                : FutureBuilder<Uint8List>(
                    future: widget.asset.thumbData,
                    builder: (BuildContext context, snapshot) {
                      Widget w;
                      if (snapshot.hasError) {
                        w = ErrorWidget(snapshot.error);
                      } else if (snapshot.hasData) {
                        _thumbData = snapshot.data;
                        w = Image.memory(
                          snapshot.data,
                          fit: BoxFit.cover,
                        );
                      } else {
                        w = Center(
                          child: Container(
                            color: Colors.white,
                            padding: const EdgeInsets.all(20),
                            child: CircularProgressIndicator(),
                          ),
                        );
                      }
                      return w;
                    },
                  ),
          ),
          onTap: () {},
        ),
        Positioned(
          top: 6,
          right: 6,
          child: ValueListenableBuilder(
            valueListenable: _checked,
            builder: (BuildContext context, bool value, Widget child) {
              return GestureDetector(
                behavior: HitTestBehavior.opaque,
                onTap: () {
                  _checked.value = !value;
                },
                child: Icon(
                  IconFont.list_update_complete,
                  size: 24,
                  color: value ? theme.toggleColor : Colors.white,
                ),
              );
            },
          ),
        ),
      ],
    );
  }
}