app-zj/lib/page/signature/signature_page.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:lszlgl/base/base_lifecycle_state.dart';
import 'package:signature/signature.dart';
import 'package:lszlgl/widget/button.dart';

class SignaturePageArgs {
  /// 签名数量
  int count;

  SignaturePageArgs({this.count = 1});

  @override
  String toString() {
    return {'count': count}.toString();
  }
}

/// 电子签名
class SignaturePage extends StatefulWidget {
  final SignaturePageArgs args;

  const SignaturePage({
    super.key,
    required this.args,
  });

  @override
  State<SignaturePage> createState() => _SignaturePageState();
}

class _SignaturePageState extends BaseLifecycleState<SignaturePage> {
  late int count;
  late List<SignatureController> ctrlList;
  late PageController pageCtrl;

  final previousEnable = false.notifier<bool>();
  final nextEnable = false.notifier<bool>();
  final submitEnable = false.notifier<bool>();

  /// 清除当前签名
  void clearCurrent() {
    ctrlList[pageCtrl.page!.toInt()].clear();
  }

  /// 上一个
  void previousPage() {
    pageCtrl.jumpToPage(pageCtrl.page!.toInt() - 1);
    if (pageCtrl.page == 0) {
      previousEnable.value = false;
    }
    nextEnable.value = true;
    submitEnable.value = false;
  }

  /// 下一个
  void nextPage() {
    if (!checkCurrentPage()) return;
    pageCtrl.jumpToPage(pageCtrl.page!.toInt() + 1);
    if (pageCtrl.page == count - 1) {
      nextEnable.value = false;
      submitEnable.value = true;
    }
    previousEnable.value = true;
  }

  void submit() async {
    if (!checkCurrentPage()) return;
    // 取出所有签名资源
    List<Uint8List?> images = [];
    for (var ctrl in ctrlList) {
      images.add(await ctrl.toPngBytes());
    }
    MyNavigator.pop(images);
  }

  bool checkCurrentPage() {
    if (ctrlList[pageCtrl.page!.toInt()].isEmpty) {
      MyNavigator.showToast('请先签名');
      return false;
    }
    return true;
  }

  @override
  void onInit() {
    // 强制横屏
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.landscapeLeft,
      DeviceOrientation.landscapeRight,
    ]);
    // 创建签名列表
    count = widget.args.count;
    ctrlList = List.generate(
      count,
      (index) => SignatureController(
        penStrokeWidth: 6,
        penColor: Colors.black,
        strokeJoin: StrokeJoin.round,
        strokeCap: StrokeCap.round,
      ),
    ).toList();
    pageCtrl = PageController();
    if (count == 1) {
      submitEnable.value = true;
    } else {
      nextEnable.value = true;
    }
  }

  @override
  void onDestroy() {
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.portraitUp,
      DeviceOrientation.portraitDown,
    ]);
    for (var ctrl in ctrlList) {
      ctrl.dispose();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(
        children: [
          SizedBox(width: double.infinity, child: Image.asset(imgHomeTopBg, fit: BoxFit.cover)),
          buildBody(),
        ],
      ),
    );
  }

  Widget buildBody() {
    return Column(
      children: [
        myAppBar(title: '电子签名', toolbarHeight: 32),
        Expanded(
          child: Container(
            decoration: const BoxDecoration(
              color: Colors.white,
            ),
            width: double.infinity,
            child: PageView.builder(
              controller: pageCtrl,
              physics: const NeverScrollableScrollPhysics(),
              itemBuilder: (_, index) => Signature(
                controller: ctrlList[index],
                backgroundColor: Colors.transparent,
              ),
            ),
          ),
        ),
        buildBottom(),
      ],
    );
  }

  Widget buildBottom() {
    EdgeInsets margin = EdgeInsets.only(left: 8, right: 8, top: 8, bottom: getBottomPadding(8));
    return Row(
      children: [
        Expanded(child: MyButton('清除重写', onTap: clearCurrent, margin: margin)),
        previousEnable.builder(
            (v) => v ? Expanded(child: MyButton('上一位', onTap: previousPage, margin: margin)) : const SizedBox.shrink()),
        nextEnable.builder(
            (v) => v ? Expanded(child: MyButton('下一位', onTap: nextPage, margin: margin)) : const SizedBox.shrink()),
        submitEnable.builder(
            (v) => v ? Expanded(child: MyButton('提交', onTap: submit, margin: margin)) : const SizedBox.shrink()),
      ],
    );
  }
}