【flutter滑动拼图验证码】

Java后台使用aj_captcha插件，提供/captcha/get（获取captcha底图和拼块图片）、/captcha/check（验证拼图偏移量）这两个接口。并且这个插件在GitHub上有源码。
1.先准备好aj_captcha的工具类：

import 'dart:convert';

import 'package:steel_crypt/steel_crypt.dart';
//import 'package:encrypt/encrypt.dart';

class EncryptUtil {
    
    
  ///aes加密
  /// [key]AesCrypt加密key
  /// [content] 需要加密的内容字符串
  static String aesEncode({
    
    String key, String content}) {
    
    
    // var aesEncrypter = AesCrypt(key, 'ecb', 'pkcs7');

    var encodeKey = base64UrlEncode(utf8.encode(key));
    var aesEncrypter = AesCrypt(padding: PaddingAES.pkcs7, key: encodeKey);
    return aesEncrypter.ecb.encrypt(inp: content);
  }

  ///aes解密
  /// [key]aes解密key
  /// [content] 需要加密的内容字符串
  static String aesDecode({
    
    String key, String content}) {
    
    
    // var aesEncrypter = AesCrypt(key, 'ecb', 'pkcs7');
    var encodeKey = base64UrlEncode(utf8.encode(key));
    var aesEncrypter = AesCrypt(key: encodeKey, padding: PaddingAES.pkcs7);
    // return aesEncrypter.decrypt(content);
    return aesEncrypter.ecb.decrypt(enc: content);
  }
}

import 'dart:convert';

class ObjectUtils {
    
    
  /// isEmpty.
  static bool isEmpty(Object value) {
    
    
    if (value == null) return true;
    if (value is String && value.isEmpty) {
    
    
      return true;
    }
    return false;
  }

  //list length == 0  || list == null
  static bool isListEmpty(Object value) {
    
    
    if (value == null) return true;
    if (value is List && value.length == 0) {
    
    
      return true;
    }
    return false;
  }

  static String jsonFormat(Map<dynamic, dynamic> map) {
    
    
    Map _map = Map<String, Object>.from(map);
    JsonEncoder encoder = JsonEncoder.withIndent('  ');
    return encoder.convert(_map);
  }
}

import 'dart:async';
import 'package:flutter/widgets.dart';
import 'object_utils.dart';

/// Widget Util.
class WidgetUtil {
    
    
  bool _hasMeasured = false;
  double _width;
  double _height;

  /// Widget rendering listener.
  /// Widget渲染监听.
  /// context: Widget context.
  /// isOnce: true,Continuous monitoring  false,Listen only once.
  /// onCallBack: Widget Rect CallBack.
  void asyncPrepare(
      BuildContext context, bool isOnce, ValueChanged<Rect> onCallBack) {
    
    
    if (_hasMeasured) return;
    WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
    
    
      RenderBox box = context.findRenderObject();
      if (box != null && box.semanticBounds != null) {
    
    
        if (isOnce) _hasMeasured = true;
        double width = box.semanticBounds.width;
        double height = box.semanticBounds.height;
        if (_width != width || _height != height) {
    
    
          _width = width;
          _height = height;
          if (onCallBack != null) onCallBack(box.semanticBounds);
        }
      }
    });
  }

  /// Widget渲染监听.
  void asyncPrepares(bool isOnce, ValueChanged<Rect> onCallBack) {
    
    
    if (_hasMeasured) return;
    WidgetsBinding.instance.addPostFrameCallback((Duration timeStamp) {
    
    
      if (isOnce) _hasMeasured = true;
      if (onCallBack != null) onCallBack(null);
    });
  }

  ///get Widget Bounds (width, height, left, top, right, bottom and so on).Widgets must be rendered completely.
  ///获取widget Rect
  static Rect getWidgetBounds(BuildContext context) {
    
    
    RenderBox box = context.findRenderObject();
    return (box != null && box.semanticBounds != null)
        ? box.semanticBounds
        : Rect.zero;
  }

  ///Get the coordinates of the widget on the screen.Widgets must be rendered completely.
  ///获取widget在屏幕上的坐标,widget必须渲染完成
  static Offset getWidgetLocalToGlobal(BuildContext context) {
    
    
    RenderBox box = context.findRenderObject();
    return box == null ? Offset.zero : box.localToGlobal(Offset.zero);
  }

  /// get image width height，load error return Rect.zero.（unit px）
  /// 获取图片宽高，加载错误情况返回 Rect.zero.（单位 px）
  /// image
  /// url network
  /// local url , package
  static Future<Rect> getImageWH(
      {
    
    Image image, String url, String localUrl, String package}) {
    
    
    if (ObjectUtils.isEmpty(image) &&
        ObjectUtils.isEmpty(url) &&
        ObjectUtils.isEmpty(localUrl)) {
    
    
      return Future.value(Rect.zero);
    }
    Completer<Rect> completer = Completer<Rect>();
    Image img = image != null
        ? image
        : ((url != null && url.isNotEmpty)
            ? Image.network(url)
            : Image.asset(localUrl, package: package));
    img.image
        .resolve(new ImageConfiguration())
        .addListener(new ImageStreamListener(
          (ImageInfo info, bool _) {
    
    
            completer.complete(Rect.fromLTWH(0, 0, info.image.width.toDouble(),
                info.image.height.toDouble()));
          },
          onError: (dynamic exception, StackTrace stackTrace) {
    
    
            completer.completeError(exception, stackTrace);
          },
        ));
    return completer.future;
  }

  /// get image width height, load error throw exception.（unit px）
  /// 获取图片宽高，加载错误会抛出异常.（单位 px）
  /// image
  /// url network
  /// local url (full path/全路径，example："assets/images/ali_connors.png"，""assets/images/3.0x/ali_connors.png"" );
  /// package
  static Future<Rect> getImageWHE(
      {
    
    Image image, String url, String localUrl, String package}) {
    
    
    if (ObjectUtils.isEmpty(image) &&
        ObjectUtils.isEmpty(url) &&
        ObjectUtils.isEmpty(localUrl)) {
    
    
      return Future.error("image is null.");
    }
    Completer<Rect> completer = Completer<Rect>();
    Image img = image != null
        ? image
        : ((url != null && url.isNotEmpty)
            ? Image.network(url)
            : Image.asset(localUrl, package: package));
    img.image
        .resolve(new ImageConfiguration())
        .addListener(new ImageStreamListener(
          (ImageInfo info, bool _) {
    
    
            completer.complete(Rect.fromLTWH(0, 0, info.image.width.toDouble(),
                info.image.height.toDouble()));
          },
          onError: (dynamic exception, StackTrace stackTrace) {
    
    
            completer.completeError(exception, stackTrace);
          },
        ));

    return completer.future;
  }
}

2.绘制验证弹窗

import 'dart:convert';
import 'package:test/constant.dart';
import 'package:test/generated/l10n.dart';
import 'package:test/http/DioManager.dart';
import 'package:tset/util/easy_loading_util.dart';
import 'package:test/util/encrypt_util.dart';
import 'package:test/util/object_utils.dart';
import 'package:test/util/widtet_util.dart';
import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';



typedef VoidSuccessCallback = dynamic Function(String c);

class CaptchaPage extends StatefulWidget {
    
    
  final VoidSuccessCallback onSuccess; //拖放完成后验证成功回调
  final VoidCallback onFail; //拖放完成后验证失败回调

  CaptchaPage({
    
    this.onSuccess, this.onFail});

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

class _CaptchaPageState extends State<CaptchaPage>
    with TickerProviderStateMixin {
    
    
  /// 是否启用
  bool enable = true;

//  String baseImageBase64 =
//      "/9j/4AAQSkZJRgABAQEASABIAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKSj/2wBDAQcHBwoIChMKChMoGhYaKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCj/wAARCADIAlgDASIAAhEBAxEB/8QAHAABAAMBAQEBAQAAAAAAAAAAAAUGBwQIAwIB/8QASBAAAQMDAQUEBQYLBQkAAAAAAAECAwQFEQYHEiExURMiQWEycYGRoQgUI0KCsRUkM1JicpLB0eHwNDVzorM3U2NkdZOy0vH/xAAaAQEAAwEBAQAAAAAAAAAAAAAAAgMEBQEG/8QAMhEBAAIBAgMECQQCAwAAAAAAAAECAwQRBSExEkFR8BMiMmFxgaGxwQaR0eEUI0Jisv/aAAwDAQACEQMRAD8A9UgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAR9TeaCnXD6hrndGIrvuPYiZ6I2vWkb2nZIAr8mq6Fi4SGqcnVGt/ep+otWWt/5R80P68ar/wCOSfor+DNOv00TtN4hPA56Otpa1iupKiKZE57jkXHr6HQQmNurTW1bx2qzvAADxIBE3/UNusUSOrpvpHJlkLE3nu9SdPNcIZreto12qn9na446JiqiNXd7SRfemOPTHtNen0WXUc6xy8ZcnXca0mhnsZLb28I5z/XzbADB32XWl8Y50kd0lYq5xUTdm32Ne5PghyybMNSObvJRU+907duToV4Vg6ZNRWJ8++GGvHNRk549LaY+cfiXoIHnOWxa9sDGvp4rxDGi5RKWdZW+1rHLw9aHZY9r19t0vZXqCG5RNVUeqtSGZvtRN3h03U9ZZbgGS9e1pslb/CfMfVox8cxxPZ1FLUn3x5+z0ACvaS1hZtVQK61VP07EzJTSpuyxp1VvinFOKZTzLCcTLivhtNMkbTHdLs48lcle1Sd4AAVpgIu/ahs+n4Emvdzo6CN2d3t5Uar8eDUXi5fJMmf3Pbxoqj/ss1xuC/8ALUjm/wCpuGvBoNTqI3xY5mPGI5fv0Rm9Y5TLVAY3D8obSj3okluv0Lc+k+CJUT9mRVLXY9rOibzIkVNf6aCZcfR1jXUy56IsiIir6lUnl4bq8Ub3xz+yUc+i8gNVHIitVFReKKniDCAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHLX1sdIzvd6ReTE/rgh9KudKeFXc3LwanVSEgpZLhUOc9yozPff+5P64E6Viec9EbTPc4qmatukqxsRz0/MZwanr/mfeDTDn4WqqEani2JM/Ff4Fjghjp40jhYjGJ4IfQnOaY5V5KZ01bTvfmgU0rb8Yc6ocvVXp+5DlqdG0j2r2FTURu8N7DkT2YRfiWgEYzXjvV34fpskbWpDNLnpm6W1/wA4pcztZxSWnVWyN88c/cqnXYNbPic2C8L2kS8EqGp3m/rInNPNOPkpoBVtW6Wjucb6qga2KvTiqJwbN5L5+fv8tFM1cnq5Y+bh6nhWo0MzqOG2neOtZ5xP8/fwlZ43sljbJG5r2ORHNc1coqLyVFKrrbVbbPGtJQq19xenFeaQovivVeie1eGEWoWHU9ZYaeqo3Rue1EckccnBYZc8fZnOU69Mqf3R1gfqG4y1lwc91LG/elcvOZ68d3PxX+eUsppq45m+X2Y+rFn/AFDl1+Oml0Fdst+U/wDXx5/nuju3fDT2lq/U07q6umfHSvd3538Xy9d3PuzyTzxg02y2C22aNG0FKxkmMOlcm9I71uXj7OXkScbGxsayNqNY1ERrWphEToh/SnPq8mbl0jwdzhfBNPw+va27WTvtPXf3eHncABldkIPUulLNqSBzLrRRySYw2dqbsrOmHpx8c4XKdUUnATx5b4rRfHO0+5C+OuSvZvG8PNmuNB3fRFUy7WuomloYn5jrIu7LTqvLfROXTeTgvJcZRF0vZTtGj1NG22XdzIb3G3LVTg2qanNzU8HInNvtThlG6NNHHNE+KZjZIntVrmOTKOReCoqeKHm3apoyXRd6p7nZnyR2+aXfp3tXvUsyd5GZ6cMtXoiovLK/VaXU4+NU/wAXV8ssezb8T55+6XCzYL8Mt6fBzx98eHnzyekaiaKmgknqJGRQxNV75HuRrWNRMqqqvBERPE8/bSNtlRO6Wh0avzenTLX3CRnff/htX0U81TPHgiYyQOvdoV31pQ260wwvijc1jZ4IEVVq6jOEwicVbnCtZ1XjnCY1HZTstpdNwxXO+RR1N9ciOai4cyk8m+Cv6u9icMq73Bw/TcIxf5PEY7V59mn5nztHvlfOrya2/o9Nyr3yyHTmyHV2raj8I3Z7rfHOqOfVXJzpKiROqMVd5eX11b5Gi235POn4o2Lc7vdqqZPS7JY4Y1+zuucn7RtQMGq/Uuuzz6tuxXwiPz1b8Wkx448ZZFUfJ/0fLHuxz3iB35zKlqr/AJmqnwKfqT5OdQxkkmm74yf82muEW6qp45lZwz9j2no0GSnGtbSd/STPx5tVZ7PR40tt911sjuzKKZtRRxKquSgq/paWZOarGqLjxTKsVFzz6HpPZltJtGvaR6UmaS6QtR09BK5Fe1OW81frsyuMoiYymUTKFm1DY7ZqK1y2690cVZRyc45E5L1RU4tVPBUVFQ8mbRNE3rZRqijudoq6j5l2u9b7i1E3o3YX6KThje3c803Xtzw9JE31vp+LR2bRFMvj3T5/dor2cvKeUvYoKZsp1zT670wyuakcNxhVIq2mav5OTHNEXjuuTii+tMqqKXM4GXFbFecd42mFExNZ2kABW8AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAPzK7djc7ogEXWq6oqEYzrut/iScETYYmxs5J8ThoGb1Q5y/UT4r/SkiTvPcAAIAAAAAApWt9KSXKqirLajUqJHNjnavBFTkj/Z4+Xq42q00ENst0FHTJ9HE3GV5uXxVfNV4nWcb7nSMu0VsdMiV0sLqhkW6vGNqoiuzjHNye8tnJe9Yp3QwYeHafT6i+qpG1r9f6+Pf4y7AAVN4AAAK9dtaaftNHeaq4XBIYLPJHFXO7J7uxdJu7iYRqqud9vLPMsJO2O1Y3tG3nf8x+7yJiQjdSWal1BZKu2VzVWCoZu5Tmx3Nrk80VEX2EkDyl7Y7Res7TDy1YtE1t0lkuyXZtLYrnUXa/MY6thkfDSMauWo1Mosv2vDlhFXPPhrQBp1uty63LOXNPP7KtNpqabHGPH0AAZF4AABEat0/Rap07W2e5szT1LFbvJ6UbubXt82rhU9RLglW00tFqztMETs8ebMbtW7NtrP4OujuzhdUfg2vblUYqK7DJUzjgiq1yKv1XO6nsM8sfKosbKPWdBdI2MYy6UitkxzdLEqIrl+w+NPsnojZ/d337Q9iucr0fPU0cT5XJ4ybqI//Minb4tEZ8WLWR/yjafjHmV+ae1EXT4AOEoAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAPlU/kHf14n1PxOmYXp5HsdRzW7nL1yh2HBbn/TSM6oip7P/p3ntupIACIAAAAABTaz/a9a/wDo1T/rRFyK3ftN1Fwv1Nd7fd5rdVwUz6XLII5UcxzmuXg9F8WoW4ZiJneduUqssTMRtG/ODX16qrLZoPwakSXGvq4aCmdKiqxkkrt1HORPBEyvsQiKupvmlbxYvwle3Xi33OqbQStmpo4nxSua5zXsWNE7uW4VHZVOqnbVaRrbnR1VJftQVNdTSNY6Hdp4oJKeZrt5srHsTmmE4Lw588n7o9K1cl3oa/UN7muzqBVdSw/N2QRteqbvaORvpPwqoi8ETK4RC6k46V2mYnrvy68uW07cvp81NoyWtvETHTbn08d+fP6/JTNTatu1C7UNVT6gWWqt0zuyoKC2unpGMaqdyebs8o9UzvYe1Grn1Flqq286g1jX2i1XVbPRWymhknkhgjlmlllRytRFka5qNRG8eGc/D41uzuaotdws8OoaumsVVJJL81jgj32ue7fVqyKmXM3lXhzxwVyoS910vUyXn8K2S8TWuufA2mnxCyaOdjVVWq5q47yZXC58uRr9Lp9oiu2+085jlHs9Y2+PjtM9VUUzxO877cuW/wAenP4eG/gyyuueodM6f2mV6XCJL9Dc6CP55DA1GvRewj3tx281FWNeKccKq48Cztq9XX7atqqyUGoktlitkdHLmOkikna6SJy7jFe1W7rlRznK5HKm61G4RVJObZlTz6fv9sqLvWzOvNVDVz1MjGb6PY9j1wiIiYVWcscEXCcix2jTcVt1bqC/MqJHy3hlMx8StRGx9i1zUwvjne+BPNqsE1tNdptty9X3Y47491tvD5r8VbxERb7/AB/pnNLrPU9bpqz2elrKRNTVt6qbK+5up03Ejp1kV9QkXo7+6xMM9FVzyTgkpSVGrLLtYstkuWolutjrqKpqG9pSwxTLIzcRWvVjUTCbyKiojc7youcZPnq/SMVj0ivzenvlynjvrrxFPams+c0ckj3OV7Y3ZSVqbytVmHbyOXgmMpF6Gs91ue1iC/1cuo6umoLdLTvr7xRtomyyPc3djhg3GOa1Gq5VeqLlU8OGff8AValr1iIrtbujffu28O7aOXuhbz6NoABxVgAAAAAAADAflaMYtBph6/lEnnanqVrc/FELz8nlyu2P2HeXOFqGp6kqJUT4GX/KwubJL9p+2NVUfS00tVJ0xI5rW/6T/ebNshtq2nZjpqlc1Wv+ZMme1UwqOk+kci+1yn0Grr2OE4Yt1mZn/wBfyn2t67LeAD59AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQ0zlpKxHYXDV96KTDXI5qOauWqmUVPE47pTLNDvRpmRvh1ToRtrubad3YVLsRKvdev1V6L5FvZ7dd46veqfABU8AAAAIbVWoqPTduWpq3b0r8pDA1e9K7onROq+HuRZVrN57NeqN71pWbWnaIcmsNWUmmvmrJWrNPM9FWNi95see8/+CeK+pSwwTR1EEc0D2yRSNR7HtXKOaqZRUPPe5eNWXC5XBkLqiaNizTbid1jU5Mb7M4TmuF5qXLZNqpjEbZK6VEY5c0b3csrxWPPxT2p0Q35tF2Me9ecx1cDTcYtbVdjLG1Lez8Y/n6TtDVQAc59CAAAAAB+KiaOngkmne2OKNqve9y4RrUTKqp+zK9rWp2ysdZKCRHNRc1b28spyjz6+K+xOqGnSaa2pyxjj5+6GHiOvx6DBOa/yjxnwW3ResKTVHztkTVgqIHriJ6950We6/7kVOOF9aFnPOK0950fcbbcViWnmkYk0W+mWvavNjvZjKc0ynJTc9JakotTW1KmjXclZhJ4HL3ondF6ovHC+PryibeJcPjD/uwc6T9J8/w5/B+Kzqo9BqOWWO7pvHn+U2ADku8AAAfKsqYKKknqquVkNNAx0ssj1w1jWplVVeiIh9TzVt52nRXuOTTmnpkfa2P/AByrYvCoci8I2L4sReKr9ZUTHD0ulwvhuXiOeMVI5d8+EeeinPnrhrvZSnpPtY2v8GSJTXKqTLVyixUcaIi557q7jfVvv8z2S1qNajWoiNRMIickMo2BbP36Vs0l3u8Kx3u4sRFjemHU0PNI+qOVe877KY7vHWDXx7V482aMOD2McbR+ftEfLd7h37O9usgAOEtAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAhr1aFqUdLS4SVeLmLwR38FJkEq2ms7w9idlEpb5WWiRYZGLJE3gsMndc31L4E7R6ttM+ElnWmev1Z03U/a9H4kncLdSXCPcq4WyY5LycnqVOKFVuOg45VVaOufH+jKxH/FFT95pi2HJ7fKXu8StEd2t0jd6O4Uj29WzNVPvOSt1RY6JrlqLtRIrebWyo937Lcr8CgVWzm7vcvZz256dXve1fduKfiDZZXy/2q50sCf8KJ0v3q0sjBpo52yIW3jo7dRbVIImPisNK6aTklRUIrWJ5o30l9u6U6yWG+65uS1tTLJ2DlxJXTp3cZ9GNvDPjwTCJ448dJsuzaxW97ZapklxmTj+MqisRf1Ewip68l0Y1rGo1iI1rUwiImERCU6rFgjbTxz8ZY8mlnPP+2eXg4LDZ6OxW2Oht0e5E3irl4ukd4ucviq/yTCIiGY7SNEvoppbxZY1dSuVX1FOznCvNXt/R8VTw58vR14GXFqL479vrv197zWcPxavD6G0bbdPczHQ+0NjoYqLUEmHJhsdYvJyeCSdF/S5dcc10yN7ZI2vjc17HIjmuauUVF5KilE1Xs6pLjI+qs72UVW7i6NU+hkXrhPRXzTh5Z4lJjdqbRz1aqVNJCi9O0gdn3tyuPJTTbDi1HrYp2nwcWNfrOF+prKTekdLR+f72n4tzBl1BtMq0Z+OW+CZ3g6KRY/gqOJJNpMCt/u2Xe6dqmPuKJ0mWO5qr+peGzG85NvjE/wv5/JHtjY58jmtY1FVznLhERPFTNavaNVPbikoIYl6ySLJ8ERCGcuotVvRPxiohVem5C3HublM+ak6aK3W87QyZv1XppnsaStstp6RETH35/RP6y121IpKKxPVXrlr6tOSJ4ozz/S92eaR+z/Ra1UsV2u8apToqPghdzlXwe79Honjz5c7FprQlLb3sqLm5lXUpxazH0bF9S+kvr93iXMuvq6YaTi0/f1k0fC9Trc0azifd7NO6Pj5+Pgj79Z6O+22ShuEe/C/iipwcx3g5q+Cp/JcoqoYdftPX7QtxSuoppEhauGVsCd3GfRkbxx4cFyi+Z6BP49rXtVr0RzVTCoqZRUI6LiF9JvXbtVnrEurxDhWPW7X37N46WhlendrlM9rIdQ0roJOS1FOivjXzVvpJ4ct72F3odY6crY2up73b+9yZJM2N/7LsL8CFv8AsxsF0c6Snjkt8y8c0yojFX9RcoierBSLlsXuKJ+IXajn/wAeJ0X3bx0Ix8K1POLTjnw7vz92OuTium9W9YyR4x1/H2a1PqOyU7N6ovNtib1fVManxUq1/wBrOlLQ16RVr7jO1cdlRM30Xz31wzH2jOm7FNQOem/WWhjc8VbJI5fduJ95O2vYVRtejrxeZ52/7uliSL2K5yuynsQurouD4fWy55t7oj+p+8Lo1XEMvKuKK/GWe602j6j11Mlpt1PJS0c/dSgo8ySz8OT3ImXJz4IiJjnnGTQtkuyBljqYL1qhsU1zjw+npEVHR0zvznLyc9PDHBq8UyuFTTNNaWsumYHR2S3w0quTD5Ey6R/6z1y5fUq8CaI63j0eh/xdBT0ePv8AGfPfzmZ8WnT6G0W9LqLdq30gAB826IAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACIq9NWWrVVmtlLvKuVcyNGOX2twpxpojTycrev/AH5P/YsYLIy3jpaWPJw/SZJ3virM++sfwiqTTtnpMdjbqZFRco5zEeqe1cqSoBCbTbrK/Fgx4Y2xVise6NgAHi0AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAf//Z";
  String baseImageBase64 = "";
  String slideImageBase64 = "";
  String captchaToken = "";
  String secretKey = "";
  Size baseSize = Size.zero; //底部基类图片
  Size slideSize = Size.zero; //滑块图片

  var sliderColor = Colors.white; //滑块的背景色
  var sliderIcon = Icons.arrow_forward; //滑块的图标
  var movedXBorderColor = Colors.white; //滑块拖动时，左边已滑的区域边框颜色
  double sliderStartX = 0; //滑块未拖前的X坐标
  double sliderXMoved = 0;
  bool sliderMoveFinish = false; //滑块拖动结束
  bool checkResultAfterDrag = false; //拖动后的校验结果

  //-------------动画------------
  int _checkMilliseconds = 0; //滑动时间
  bool _showTimeLine = false; //是否显示动画部件
  bool _checkSuccess = false; //校验是否成功
  AnimationController controller;


  var _ratio = 3.0;
  var dialogWidth;
  GlobalKey _baseImageKey = new GlobalKey();
  //高度动画
  Animation<double> offsetAnimation;

  //------------动画------------

  //校验通过
  void checkSuccess(String content) {
    
    
    setState(() {
    
    
      checkResultAfterDrag = true;
      _checkSuccess = true;
      _showTimeLine = true;
    });
    _forwardAnimation();
    updateSliderColorIcon();

    //刷新验证码
    Future.delayed(Duration(milliseconds: 1000)).then((v) {
    
    
      _reverseAnimation().then((v) {
    
    
        setState(() {
    
    
          _showTimeLine = false;
        });
        //回调
        if (widget.onSuccess != null) {
    
    
          widget.onSuccess(content);
          // NavigatorUtil.pop(value: true);
        }
        Navigator.pop(context);
      });
    });
  }

  //校验失败
  void checkFail() {
    
    
    setState(() {
    
    
      _showTimeLine = true;
      _checkSuccess = false;
      checkResultAfterDrag = false;
    });
    _forwardAnimation();
    updateSliderColorIcon();

    //刷新验证码
    Future.delayed(Duration(milliseconds: 1000)).then((v) {
    
    
      _reverseAnimation().then((v) {
    
    
        setState(() {
    
    
          _showTimeLine = false;
        });
        loadCaptcha();
        //回调
        if (widget.onFail != null) {
    
    
          widget.onFail();
        }
      });
    });
  }

  //重设滑动颜色与图标
  void updateSliderColorIcon() {
    
    
    var _sliderColor = null; //滑块的背景色
    var _sliderIcon = null; //滑块的图标
    var _movedXBorderColor = null; //滑块拖动时，左边已滑的区域边框颜色

    //滑块的背景色
    if (sliderMoveFinish) {
    
    
      //拖动结束
      _sliderColor = checkResultAfterDrag ? Colors.green : Colors.red;
      _sliderIcon = checkResultAfterDrag ? Icons.check : Icons.close;
      _movedXBorderColor = checkResultAfterDrag ? Colors.green : Colors.red;
    } else {
    
    
      //拖动未开始或正在拖动中
      _sliderColor = sliderXMoved > 0 ? Color(0xffe63850) : Colors.white;
      _sliderIcon = Icons.arrow_forward;
      _movedXBorderColor = Color(0xff89F2D0);
    }

    sliderColor = _sliderColor;
    sliderIcon = _sliderIcon;
    movedXBorderColor = _movedXBorderColor;
    setState(() {
    
    });
  }

  //加载验证码
  void loadCaptcha() {
    
    
    setState(() {
    
    
      _showTimeLine = false;
      sliderMoveFinish = false;
      checkResultAfterDrag = false;
      sliderColor = Colors.white; //滑块的背景色
      sliderIcon = Icons.arrow_forward; //滑块的图标
      movedXBorderColor = Colors.white; //滑块拖动时，左边已滑的区域边框颜色
    });
    DioManager.getInstance()
        .post(Constant.baseUrl + '/captcha/get', {
    
    "captchaType": "blockPuzzle"},
            (res) async {
    
    
      if (res['repCode'] != '0000' || res['repData'] == null) {
    
    
        setState(() {
    
    
          secretKey = "";
        });
        if (res['repCode'] == '6202') {
    
    
          enable = false;
          esLoadingError('您失败的次数太多啦，请稍后试试吧！');
        }

        return;
      }

      Map<String, dynamic> repData = res['repData'];
      print("--------------");
      print(repData.keys);
      print("${repData["point"]}");

      sliderXMoved = 0;
      sliderStartX = 0;
      captchaToken = '';
      checkResultAfterDrag = false;

      baseImageBase64 = repData["originalImageBase64"];
      baseImageBase64 = baseImageBase64.replaceAll('\n', '');
      secretKey = repData['secretKey'] ?? "";
      slideImageBase64 = repData["jigsawImageBase64"];
      slideImageBase64 = slideImageBase64.replaceAll('\n', '');
      captchaToken = repData["token"];

      print(baseImageBase64);

      var baseR = await WidgetUtil.getImageWH(
          image: Image.memory(Base64Decoder().convert(baseImageBase64)));
      baseSize = baseR.size;

      var silderR = await WidgetUtil.getImageWH(
          image: Image.memory(Base64Decoder().convert(slideImageBase64)));
      slideSize = silderR.size;
      enable = true;
      setState(() {
    
    });
    }, (error) {
    
    
      print(error);
    });
  }

  //校验验证码
  void checkCaptcha(sliderXMoved, captchaToken, {
    
    BuildContext myContext}) {
    
    
    setState(() {
    
    
      sliderMoveFinish = true;
    });
    //滑动结束，改变滑块的图标及颜色
//    updateSliderColorIcon();

    //pointJson参数需要aes加密

//    MediaQueryData mediaQuery = MediaQuery.of(myContext);
    /*
    * ScreenUtil().setHeight(20)*/

    print('sliderXMoved= $sliderXMoved');
    print('_baseImageKeyWidth ${
      
      _baseImageKey.currentContext.size.width}');
    print('_baseImageKeyWidthRatio= ${
      
      _baseImageKey.currentContext.size.width / baseSize.width}');
    //由于不同屏幕分辨率或者屏幕设置放大后拖动从最右侧拖动到同一位置的偏移量是不同的（屏幕），根据底图在屏幕上的实际宽度和从接口获取的底图的宽度（baseSize.width）的百分比来计算接口偏移量参数

    var pointMap = {
    
    "x": sliderXMoved / (_baseImageKey.currentContext.size.width / baseSize.width), "y": 5};//x:拖动的偏移量  y:偏移量误差范围 
    var pointStr = json.encode(pointMap);
    var cryptedStr = pointStr;

    /// secretKey 不为空，进行as加密
    if (!ObjectUtils.isEmpty(secretKey)) {
    
    
      // var aesEncrypter = AesCrypt(secretKey, 'ecb', 'pkcs7');
      cryptedStr = EncryptUtil.aesEncode(key: secretKey, content: pointStr);
      var dcrypt = EncryptUtil.aesDecode(key: secretKey, content: cryptedStr);
      // Map _map = json.decode(dcrypt);
    }

    // print("dcrypt ---- ${_map}");
    DioManager.getInstance().post(Constant.baseUrl + '/captcha/check', {
    
    
      "pointJson": cryptedStr,
      "captchaType": "blockPuzzle",
      "token": captchaToken
    }, (res) {
    
    
      if (res['repCode'] != '0000' || res['repData'] == null) {
    
    
        checkFail();
        return;
      }

      Map<String, dynamic> repData = res['repData'];
      if (repData["result"] != null && repData["result"] == true) {
    
    
        // 如果不加密 将 token 和 坐标序列化 通过 --- 链接成字符串

        var captchaVerification = '$captchaToken---$pointStr';
        if (!ObjectUtils.isEmpty(secretKey)) {
    
    
          // 如果加密 将 token 和 坐标序列化通过 --- 链接成字符串进行加密 加密秘钥为 _clickWordCaptchaModel.secretKey
          captchaVerification = EncryptUtil.aesEncode(
              key: secretKey, content: captchaVerification);
        }

        checkSuccess(captchaVerification);
      } else {
    
    
        checkFail();
      }
    }, (error) {
    
    
      loadCaptcha();
      print(error);
    });
  }

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

  @override
  void dispose() {
    
    
    controller.dispose();
    super.dispose();
  }

  // 初始化动画
  void initAnimation() {
    
    
    controller =
        AnimationController(duration: Duration(milliseconds: 500), vsync: this);

    offsetAnimation = Tween<double>(begin: 0.5, end: 0)
        .animate(CurvedAnimation(parent: controller, curve: Curves.ease))
          ..addListener(() {
    
    
            this.setState(() {
    
    });
          });
  }

  // 反向执行动画
  _reverseAnimation() async {
    
    
    await controller.reverse();
  }

  // 正向执行动画
  _forwardAnimation() async {
    
    
    await controller.forward();
  }

  @override
  void didUpdateWidget(CaptchaPage oldWidget) {
    
    
    // TODO: implement didUpdateWidget
    super.didUpdateWidget(oldWidget);
  }

  @override
  Widget build(BuildContext context) {
    
    
    dialogWidth = 0.9 * MediaQuery.of(context).size.width;
   _ratio = MediaQuery.of(context).devicePixelRatio;
    return Scaffold(
      backgroundColor: Colors.transparent,
      body: MediaQuery(
        data: MediaQueryData(devicePixelRatio: _ratio),
        child: Center(
          child: UnconstrainedBox(
            child: Container(
              width: dialogWidth,
              color: Colors.white,
              child: Stack(
                children: <Widget>[
                  Column(
                    mainAxisAlignment: MainAxisAlignment.start,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      //顶部，提示+关闭
                      Container(
                        height: 50,
                        padding: EdgeInsets.fromLTRB(10, 0, 10, 0),
                        decoration: BoxDecoration(
                          border: Border(
                              bottom:
                              BorderSide(width: 1, color: Color(0xffe5e5e5))),
                        ),
                        child: Row(
                          mainAxisAlignment: MainAxisAlignment.spaceBetween,
                          children: <Widget>[
                            Expanded(
                                child: Text(
                                  S.current.qingwanchenganquanyanzheng,
                                  maxLines: 1,
                                  overflow: TextOverflow.ellipsis,
                                  style: TextStyle(fontSize: 18),
                                  textScaleFactor: 1.0,
                                )),
                            IconButton(
                                padding: EdgeInsets.all(3),
                                icon: Icon(Icons.refresh),
                                iconSize: 30,
                                color: Colors.black54,
                                onPressed: () {
    
    
                                  //刷新
                                  loadCaptcha();
                                }),
                            IconButton(
                                padding: EdgeInsets.all(3),
                                icon: Icon(Icons.highlight_off),
                                iconSize: 30,
                                color: Colors.black54,
                                onPressed: () {
    
    
                                  //退出
                                  Navigator.pop(context);
                                }),
                          ],
                        ),
                      ),

                      //显示验证码
                      Container(
                        margin: EdgeInsets.all(10),
                        child: Stack(
                          children: <Widget>[
                            //底图 310*155
                            baseImageBase64.length > 0
                                ? Image.memory(
                            Base64Decoder().convert(baseImageBase64),
                          fit: BoxFit.fitWidth,
                          key: _baseImageKey,
                          height: 310.w,
                          gaplessPlayback: true,)
                                : Container(
                              width: dialogWidth - 20,
                              height: 310.w,
                              alignment: Alignment.center,
                              child: CircularProgressIndicator(),
                            ),

                            //滑块图
                            slideImageBase64.length > 0
                                ? Container(
                              margin: EdgeInsets.fromLTRB(sliderXMoved, 0, 0, 0),
                              child: Image.memory(
                                Base64Decoder().convert(slideImageBase64),
                               height: 310.w,
                                fit: BoxFit.fitHeight,
                                gaplessPlayback: true,
                              ),
                            )
                                : Container(),

                            Positioned(
                                bottom: 0,
                                left: -10,
                                right: -10,
                                child: Offstage(
                                  offstage: !_showTimeLine,
                                  child: FractionalTranslation(
                                    translation: Offset(0, offsetAnimation.value),
                                    child: Container(
                                      margin: EdgeInsets.only(left: 10, right: 10),
                                      padding: EdgeInsets.only(left: 10),
                                      height: 40,
                                      color: _checkSuccess
                                          ? Color(0x7F66BB6A)
                                          : Color.fromRGBO(200, 100, 100, 0.4),
                                      alignment: Alignment.centerLeft,
                                      child: Text(
                                        _checkSuccess
                                            ? "${
      
      (_checkMilliseconds / (60.0 * 12)).toStringAsFixed(2)}${
      
      S.current.yanzhengchenggong}"
                                            : S.current.yanzhengshibai,
                                        style: TextStyle(color: Colors.white),
                                      ),
                                    ),
                                  ),
                                )),
                            Positioned(
                                bottom: -20,
                                left: 0,
                                right: 0,
                                child: Offstage(
                                  offstage: !_showTimeLine,
                                  child: Container(
                                    margin: EdgeInsets.only(left: 10, right: 10),
                                    height: 20,
                                    color: Colors.white,
                                  ),
                                ))
                          ],
                        ),
                      ),

                      //底部，滑动区域
                      baseSize.width > 0
                          ? Container(
                          margin: EdgeInsets.all(10),
                          height: slideSize.width * (dialogWidth - 20) / baseSize.width,
                          width: baseSize.width * 2.w,
                          child: Stack(
                            alignment: AlignmentDirectional.centerStart,
                            children: <Widget>[
                              Container(
                                height: slideSize.width * (dialogWidth - 20) / baseSize.width,
                                decoration: BoxDecoration(
                                  border: Border.all(
                                    width: 1,
                                    color: Color(0xffe5e5e5),
                                  ),
                                  color: Color(0xffe1e1e1),
                                ),
                              ),
                              Container(
                                alignment: Alignment.center,
                                child: Text(
                                  S.current.xiangyouhuadong,
                                  style: TextStyle(fontSize: 16),
                                  textScaleFactor: 1.0,
                                ),
                              ),
                              Container(
                                width: sliderXMoved,
                                height: 58,
                                decoration: BoxDecoration(
                                  border: Border.all(
                                    width: sliderXMoved > 0 ? 1 : 0,
                                    color: movedXBorderColor,
                                  ),
                                  color: Color(0xff89F2D0),
                                ),
                              ),
                              GestureDetector(
                                onPanStart: (startDetails) {
    
    
                                  if (!enable) return;

                                  _checkMilliseconds =
                                      new DateTime.now().millisecondsSinceEpoch;
                                  print("startDetails");
                                  print(startDetails.globalPosition);

                                  sliderStartX = startDetails.globalPosition.dx;
                                  print(
                                      "startDetails --- sliderStartX ${
      
      sliderStartX} ");
                                },
                                onPanUpdate: (updateDetails) {
    
    
                                  if (!enable) return;

                                  print("updateDetails");
                                  print(updateDetails.globalPosition);

                                  double offset =
                                      updateDetails.globalPosition.dx  - sliderStartX;
                                  double _w1 = baseSize.width * 2.w - 100.w;
                                  if (offset < 0) {
    
    
                                    offset = 0;
                                  } else if ((offset > _w1)) {
    
    
                                    offset = _w1;
                                  }
                                  setState(() {
    
    
                                    sliderXMoved = offset;
                                  });
                                  //滑动过程，改变滑块左边框颜色
                                  updateSliderColorIcon();
                                },
                                onPanEnd: (endDetails) {
    
    
                                  if (!enable) return;
                                  checkCaptcha(sliderXMoved, captchaToken);
                                  int _nowTime =
                                      new DateTime.now().millisecondsSinceEpoch;
                                  _checkMilliseconds =
                                      _nowTime - _checkMilliseconds;

                                  //滑动结束
                                },
                                child: Container(
                                  width: slideSize.width * (dialogWidth - 20) / baseSize.width,
                                  height: slideSize.width * (dialogWidth - 20) / baseSize.width,
                                  margin: EdgeInsets.fromLTRB(
                                      sliderXMoved > 0 ? sliderXMoved : 1,
                                      0,
                                      0,
                                      0),
                                  decoration: BoxDecoration(
                                    border: Border(
                                      top: BorderSide(
                                        width: 1,
                                        color: Color(0xffe5e5e5),
                                      ),
                                      right: BorderSide(
                                        width: 1,
                                        color: Color(0xffe5e5e5),
                                      ),
                                      bottom: BorderSide(
                                        width: 1,
                                        color: Color(0xffe5e5e5),
                                      ),
                                    ),
                                    color: sliderColor,
                                  ),
                                  child: IconButton(
                                    icon: Icon(sliderIcon),
                                    iconSize: 20,
                                    color: Colors.black54,
                                  ),
                                ),
                              )
                            ],
                          ))
                          : Container(),
                    ],
                  ),
                ],
              ),
            ),
          )

        ),
      )
    );
  }
}

3.使用：

_sendPhoneCode(setBottomSheetState) {
    
    
    showDialog<Null>(
      context: context,
      barrierDismissible: true,
      builder: (BuildContext context) {
    
    
        return CaptchaPage(
          onSuccess: (value) async {
    
    
            Response response = await _dio.post(LoginApi.SEND_MESSAGE_URL,
                data: {
    
    
                  'ic': '+$areaCode',
                  'phone': phoneController.text,
                  'captchaVerification': value
                });
            String dataStr = json.encode(response.data);
            Map<String, dynamic> dataMap = json.decode(dataStr);
            if (dataMap != null && dataMap['code'] == 200) {
    
    
              if (mounted) {
    
    
                setBottomSheetState(() {
    
    
                  isButtonEnable = false; //按钮状态标记
                });
              }

              timer = new Timer.periodic(Duration(seconds: 1), (Timer timer) {
    
    
                if (mounted) {
    
    
                  setBottomSheetState(() {
    
    
                    count--;
                    if (count == 0) {
    
    
                      timer.cancel(); //倒计时结束取消定时器
                      isButtonEnable = true; //按钮可点击
                      count = 60; //重置时间
                      buttonText = S.current.fasongyanzhengma; //重置按钮文本
                    } else {
    
    
                      buttonText = '${
      
      count}S'; //更新文本内容
                    }
                  });
                }
              });
              esLoadingToast(S.current.fasongchenggong);
            } else {
    
    
              esLoadingError(S.current.fasongshibai);
            }
          },
          onFail: () {
    
    
            // esLoadingError('人机校验失败');
          },
        );
      },
    );
  }

滑块拼图验证码