有没有办法从手机图库中读取缩略图？

Question

我正在尝试通过读取外部文件目录以及可能以 jpg 或 png 结尾的每个图像来自己显示所有手机图库图像。我实现了这一点，但由于它们的大小或编号，无法将它们全部显示在网格中。图像，应用程序崩溃。代码看起来有点像这样..

new GridView.count(
              shrinkWrap: true,
              physics: new ClampingScrollPhysics(),
              crossAxisCount: 2,
              //        children: new List<Widget>.generate(_images.length, (index) {
              //        children: new List<Widget>.generate(allImages.length, (index) {
              children: new List<Widget>.generate(_PhoneImages.length, (index) {
                File imgFile = _phoneImageFiles[index];
                thumbBytes = _phoneThumbBytes[index]; // assuming it got created!!!
//                    print('thumbbytes $thumbBytes');
                print('phone image index: $index');
                return new GridTile(
                  child: new GestureDetector(
                      child: new Stack(
                        children: [

                          new Card(
//                                color: Colors.blue.shade200,
                            color: Colors.white70,
                            child: new Center(
                              //                                  child: new Text('tile $index'),
                              //                          child: new Image.asset(_images[index]),
                              /*
                            child: new CachedNetworkImage(
                              imageUrl: allImages[index].path,
  //                            placeholder: new CircularProgressIndicator(),
                              errorWidget: new Icon(Icons.error),
                            )
                          */

                              child: new Image.file(imgFile,
//                                  child: new Image.memory(thumbBytes,

所以我尝试了 imageresize 库，它告诉我要进行繁重的调整大小操作，这需要将近 20 分钟才能显示缩略图。

我所需要的只是从画廊中读取缩略图，就像手机画廊的显示方式一样。我不需要分类。我需要所有内容和完整版本的链接，以便以后可以对它们进行操作。

Answer 1

我认为这可能会有所帮助multi_image_picker

例如

import 'package:flutter/material.dart';
import 'package:multi_image_picker/asset.dart';

class AssetView extends StatefulWidget {
  final int _index;
  final Asset _asset;

  AssetView(this._index, this._asset);

  @override
  State<StatefulWidget> createState() => AssetState(this._index, this._asset);
}

class AssetState extends State<AssetView> {
  int _index = 0;
  Asset _asset;
  AssetState(this._index, this._asset);

  @override
  void initState() {
    super.initState();
    _loadImage();
  }

  void _loadImage() async {
    await this._asset.requestThumbnail(300, 300); // here requesting thumbnail
    setState(() {});
  }

  @override
  Widget build(BuildContext context) {
    if (null != this._asset.thumbData) {
      return Image.memory(
        this._asset.thumbData.buffer.asUint8List(),
        fit: BoxFit.cover,
      );
    }

    return Text(
      '${this._index}',
      style: Theme.of(context).textTheme.headline,
    );
  }
}

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

import 'package:flutter/services.dart';
import 'package:multi_image_picker/asset.dart';
import 'package:multi_image_picker/multi_image_picker.dart';
import 'asset_view.dart';

void main() => runApp(new MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<Asset> images = List<Asset>();
  String _error;

  @override
  void initState() {
    super.initState();
  }

  Widget buildGridView() {
    return GridView.count(
      crossAxisCount: 3,
      children: List.generate(images.length, (index) {
        return AssetView(index, images[index]);
      }),
    );
  }

  Future<void> loadAssets() async {
    setState(() {
      images = List<Asset>();
    });

    List resultList;
    String error;

    try {
      resultList = await MultiImagePicker.pickImages(
        maxImages: 300,
      );
    } on PlatformException catch (e) {
      error = e.message;
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      images = resultList;
      if (error == null) _error = 'No Error Dectected';
    });
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: const Text('Plugin example app'),
        ),
        body: Column(
          children: <Widget>[
            Center(child: Text('Error: $_error')),
            RaisedButton(
              child: Text("Pick images"),
              onPressed: loadAssets,
            ),
            Expanded(
              child: buildGridView(),
            )
          ],
        ),
      ),
    );
  }
}