Flutter实现StackView

1.让界面之间可以嵌套且执行动画。

2.界面的添加遵循先进后出原则。

3.需要使用AnimateView，请看我上一篇博客。

演示：

代码：

Stack:

import 'package:flutter/cupertino.dart';

///栈，先进后出
class KqWidgetStack {
  final List _stack = [];

  ///入栈
  push(Widget obj) {
    _stack.add(obj);
  }

  ///出栈
  Widget? pop() {
    if (_stack.isEmpty) {
      return null;
    } else {
      return _stack.removeLast();
    }
  }

  ///栈长度
  length() {
    return _stack.length;
  }

  ///清除栈
  clear() {
    _stack.clear();
  }
}

StackView:

import 'package:flutter/cupertino.dart';
import 'package:kq_flutter_widgets/widgets/animate/animate_view.dart';
import 'package:kq_flutter_widgets/widgets/stackview/stack.dart';

class StackView extends StatefulWidget {
  ///初始显示的界面
  final Widget initChild;

  ///state回调。获取state后方便后续界面操作。
  final void Function(StackViewState state)? stateCallback;

  const StackView({
    super.key,
    required this.initChild,
    this.stateCallback,
  });

  @override
  State createState() => StackViewState();
}

class StackViewState extends State {
  final KqWidgetStack _stack = KqWidgetStack();
  bool _isOpen = true;
  Widget? _previousWidget;
  Widget? _currentWidget;

  @override
  void initState() {
    super.initState();
    _currentWidget = widget.initChild;
    widget.stateCallback?.call(this);
  }

  @override
  Widget build(BuildContext context) {
    if (_currentWidget == null) {
      return Container();
    } else if (_previousWidget == null) {
      return _isOpen
          ? AnimateView(
              animate: TranslationAnimate(
                  angle: TranslationAnimateDirection.bottomToTop.angle,
                  type: TranslationAnimateType.translateIn),
              child: _currentWidget!,
            )
          : AnimateView(
              animate: TranslationAnimate(
                  angle: TranslationAnimateDirection.topToBottom.angle,
                  type: TranslationAnimateType.translateOut),
              child: _currentWidget!,
            );
    } else {
      return _isOpen
          ? Stack(
              children: [
                AnimateView(
                  animate: TranslationAnimate(
                      angle: TranslationAnimateDirection.bottomToTop.angle,
                      type: TranslationAnimateType.translateOut),
                  isNeedFlashEveryTime: true,
                  child: _previousWidget!,
                ),
                AnimateView(
                  animate: TranslationAnimate(
                      angle: TranslationAnimateDirection.bottomToTop.angle,
                      type: TranslationAnimateType.translateIn),
                  isNeedFlashEveryTime: true,
                  child: _currentWidget!,
                ),
              ],
            )
          : Stack(
              children: [
                AnimateView(
                  animate: TranslationAnimate(
                      angle: TranslationAnimateDirection.topToBottom.angle,
                      type: TranslationAnimateType.translateOut),
                  isNeedFlashEveryTime: true,
                  child: _previousWidget!,
                ),
                AnimateView(
                  animate: TranslationAnimate(
                      angle: TranslationAnimateDirection.topToBottom.angle,
                      type: TranslationAnimateType.translateIn),
                  isNeedFlashEveryTime: true,
                  child: _currentWidget!,
                ),
              ],
            );
    }
  }

  addWidget(Widget page) {
    _isOpen = true;
    _previousWidget = _currentWidget;
    _currentWidget = page;
    if (_previousWidget != null) {
      _stack.push(_previousWidget!);
    }
    print("stack size=${_stack.length()}");
    setState(() {});
  }

  ///回退，返回上一个界面。
  ///[bool] 返回true表示成功返回上一级，
  ///返回false表示返回失败，已是最后一个界面，不可继续返回。
  bool back() {
    _isOpen = false;
    _previousWidget = _currentWidget;
    _currentWidget = _stack.pop();

    print("stack size=${_stack.length()}");
    setState(() {});
    if (_stack.length() > 1) {
      return true;
    } else {
      return false;
    }
  }

  @override
  void dispose() {
    super.dispose();
    _stack.clear();
  }
}

demo:

import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:kq_flutter_widgets/widgets/button/kq_small_button.dart';
import 'package:kq_flutter_widgets/widgets/stackview/stack_view.dart';
import 'package:kq_flutter_widgets/widgets/titleBar/kq_title_bar.dart';

class StackViewDemo extends StatefulWidget {
  const StackViewDemo({super.key});

  @override
  State createState() => StackViewDemoState();
}

class StackViewDemoState extends State {
  StackViewState? state;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: KqHeadBar(
        headTitle: 'StackView演示',
        back: () {
          Get.back();
        },
      ),
      body: StackView(
        initChild: Column(
          children: [
            const Text("我是首页"),
            KqSmallButton(
              title: "打开新页面",
              onTap: (disabled) {
                state?.addWidget(TestPage1(state: state!));
              },
            ),
            Expanded(child: Container(color: Colors.purple,)),
          ],
        ),
        stateCallback: (StackViewState state) {
          this.state = state;
        },
      ),
    );
  }
}

class TestPage1 extends StatelessWidget {
  final StackViewState state;

  const TestPage1({super.key, required this.state});

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        const Text("我是TestPage1"),
        KqSmallButton(
          title: "返回",
          onTap: (disabled) {
            state.back();
          },
        ),
        KqSmallButton(
          title: "打开新页面",
          onTap: (disabled) {
            state.addWidget(TestPage2(state: state));
          },
        ),
        Expanded(child: Container(color: Colors.amber,)),
      ],
    );
  }
}

class TestPage2 extends StatelessWidget {
  final StackViewState state;

  const TestPage2({super.key, required this.state});

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        const Text("我是TestPage2"),
        KqSmallButton(
          title: "返回",
          onTap: (disabled) {
            state.back();
          },
        ),
        KqSmallButton(
          title: "打开新页面",
          onTap: (disabled) {
            state.addWidget(TestPage3(state: state));
          },
        ),
        Expanded(child: Container(color: Colors.cyan,)),
      ],
    );
  }
}

class TestPage3 extends StatelessWidget {
  final StackViewState state;

  const TestPage3({super.key, required this.state});

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        const Text("我是TestPage3"),
        KqSmallButton(
          title: "返回",
          onTap: (disabled) {
            state.back();
          },
        ),
        Expanded(child: Container(color: Colors.blueAccent,)),
      ],
    );
  }
}