如何在抖动中从图像选择器裁剪图像? [英] How to crop Image from image picker in flutter?

问题描述

我想允许用户裁剪从图像选择器中选择的图像并保存(类似于在Whatsapp中上传个人资料照片).我该怎么办?

I want to allow user to crop the Image he chose from image picker and save it(Similar to uploading profile pic in Whatsapp). How can I do this in flutter?

示例图片:

推荐答案

您可以使用这两个flutter库来实现这一目标，

You can use these 2 flutter libraries to achieve this,

1. image_picker;
2. image_cropper

图像选择器使用iOS和Android中的本机库来实现它，因此它将提供良好的性能方式.

The image picker use the native libraries in iOS and Android to achieve it, therefore it will delivery a good performance way.

以下是image_picker中可用的示例:

Here is a sample available in image_picker:

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

import 'package:image_cropper/image_cropper.dart';
import 'package:image_picker/image_picker.dart';

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

class ConfigScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'ImageCropper',
      theme: ThemeData.light().copyWith(primaryColor: Colors.deepOrange),
      home: MyHomePage(
        title: 'ImageCropper',
      ),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  MyHomePage({this.title});

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

enum AppState {
  free,
  picked,
  cropped,
}

class _MyHomePageState extends State<MyHomePage> {
  AppState state;
  File imageFile;

  @override
  void initState() {
    super.initState();
    state = AppState.free;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: imageFile != null ? Image.file(imageFile) : Container(),
      ),
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.deepOrange,
        onPressed: () {
          if (state == AppState.free)
            _pickImage();
          else if (state == AppState.picked)
            _cropImage();
          else if (state == AppState.cropped) _clearImage();
        },
        child: _buildButtonIcon(),
      ),
    );
  }

  Widget _buildButtonIcon() {
    if (state == AppState.free)
      return Icon(Icons.add);
    else if (state == AppState.picked)
      return Icon(Icons.crop);
    else if (state == AppState.cropped)
      return Icon(Icons.clear);
    else
      return Container();
  }

  Future<Null> _pickImage() async {
    imageFile = await ImagePicker.pickImage(source: ImageSource.gallery);
    if (imageFile != null) {
      setState(() {
        state = AppState.picked;
      });
    }
  }

  Future<Null> _cropImage() async {
    File croppedFile = await ImageCropper.cropImage(
        sourcePath: imageFile.path,
        aspectRatioPresets: Platform.isAndroid
            ? [
                CropAspectRatioPreset.square,
                CropAspectRatioPreset.ratio3x2,
                CropAspectRatioPreset.original,
                CropAspectRatioPreset.ratio4x3,
                CropAspectRatioPreset.ratio16x9
              ]
            : [
                CropAspectRatioPreset.original,
                CropAspectRatioPreset.square,
                CropAspectRatioPreset.ratio3x2,
                CropAspectRatioPreset.ratio4x3,
                CropAspectRatioPreset.ratio5x3,
                CropAspectRatioPreset.ratio5x4,
                CropAspectRatioPreset.ratio7x5,
                CropAspectRatioPreset.ratio16x9
              ],
        androidUiSettings: AndroidUiSettings(
            toolbarTitle: 'Cropper',
            toolbarColor: Colors.deepOrange,
            toolbarWidgetColor: Colors.white,
            initAspectRatio: CropAspectRatioPreset.original,
            lockAspectRatio: false),
        iosUiSettings: IOSUiSettings(
          title: 'Cropper',
        ));
    if (croppedFile != null) {
      imageFile = croppedFile;
      setState(() {
        state = AppState.cropped;
      });
    }
  }

  void _clearImage() {
    imageFile = null;
    setState(() {
      state = AppState.free;
    });
  }
}

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