Flutter 生成二维码、图片保存、图片分享(空安全版本null safety)

使用到的库(当前版本)：

//生成二维码的库，可增加logo

qr_flutter: ^4.0.0 

//保存图片用到的库

permission_handler: ^8.1.3

image_gallery_saver: ^1.6.9

path_provider: ^1.6.24

//分享库

share: ^2.0.4

引用到文件：

import 'package:flutter/material.dart';

import 'package:flutter/rendering.dart';

import 'package:flutter/services.dart';

import 'package:image_gallery_saver/image_gallery_saver.dart';

import 'package:path_provider/path_provider.dart';

import 'package:permission_handler/permission_handler.dart';

import 'package:qr_flutter/qr_flutter.dart';

import 'package:share/share.dart';

import 'dart:ui' as ui;

生成图片文件方法

Future _shareUiImage(ui.Image uiImage) async {
    ByteData? finalByteData = await uiImage.toByteData(format: ui.ImageByteFormat.png);
    Uint8List finalPngBytes = finalByteData!.buffer.asUint8List();
    final document = await getApplicationDocumentsDirectory();
    final dir = Directory(document.path +'/Yelena_QR.png');
    final imageFile = File(dir.path);
    await imageFile.writeAsBytes(finalPngBytes);
    return imageFile;
  }

生成图片API

GlobalKey _globalKey = GlobalKey();

RepaintBoundary（

key: globalKey,

        child: Container(需要截图的部分)

）

生成图片

GlobalKey _globalKey = GlobalKey();
//注意⚠️这里有变更 增加强转，旧版API无法使用
RenderRepaintBoundary? boundary = _globalKey.currentContext?.findRenderObject()! as RenderRepaintBoundary;

 ui.Image image = await boundary.toImage();

//*******************生成二维码图片*********************

qr_flutter: ^4.0.0 //此版本调用的API优化的比较简单了，

不带logo

QrImage(
  data: 'This is a simple QR code',
  version: QrVersions.auto,
  size: 320,
  gapless: false,
)

带logo

QrImage(
  data: 'This QR code has an embedded image as well',
  version: QrVersions.auto,
  size: 320,
  gapless: false,
  embeddedImage: AssetImage('assets/images/my_embedded_image.png'),
  embeddedImageStyle: QrEmbeddedImageStyle(
    size: Size(80, 80),
  ),
)

保存图片方法

 //检查是否有存储权限
                          var status = await Permission.storage.status;
                          if (!status.isGranted) {
                            status = await Permission.storage.request();
                            print(status);
                            return;
                          }
                            
                            RenderRepaintBoundary? boundary = _globalKey.currentContext?.findRenderObject()! as RenderRepaintBoundary;
                            ui.Image image = await boundary.toImage();
                            ByteData? byteData = await image.toByteData(format: ui.ImageByteFormat.png);
                            final result = await ImageGallerySaver.saveImage(byteData!.buffer.asUint8List(),quality:100,name: 'boss_Image'+DateTime.now().toString() );
                            if (result['isSuccess'].toString()=='true') {
                              print('保存成功');
                            }else{
                              print('保存失败');
                            }

//*******************分享图片方法*********************

RenderRepaintBoundary? boundary = _globalKey.currentContext?.findRenderObject()! as RenderRepaintBoundary;
                       ui.Image image = await boundary.toImage();
                       File imageFile = await _shareUiImage(image);
                       Share.shareFiles([imageFile.path]);

//注意一、RenderRepaintBoundary的变化
//注意二、import 'dart:ui' show lerpDouble;
Error: Not found: 'dart:ui'
检查文件名是否重复

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