Flutter 60: 图解基本 Dialog 对话框小结

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Flutter 60: 图解基本 Dialog 对话框小结

阿策~ 2019-09-09 17:59:49 浏览283
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      Dialog 在日常开发中应用广泛,大家也对此很熟悉;小菜以前也整理过关于自定义 Dialog 的小博客,今天小菜系统的学习一下最基本的 Dialog

      Dialog 一般不直接使用,Flutter 提供了便利的 AlertDialog / SimpleDialog / AboutDialog / CupertinoDialog / CupertinoAlertDialog 等多种对话框样式,小菜重点尝试前三种 Android Type Dialog;但对于自定义对话框可继承 Dialog 进行处理;

AlertDialog

源码分析

const AlertDialog({
    Key key,
    this.title,     // 标题内容
    this.titlePadding,  // 标题与周围边距
    this.titleTextStyle,    // 标题样式
    this.content,   // 消息内容
    this.contentPadding = const EdgeInsets.fromLTRB(24.0, 20.0, 24.0, 24.0),      // 消息内容与周围边距
    this.contentTextStyle,  // 消息内容样式
    this.actions,   // 操作按钮组合
    this.backgroundColor,   // 对话框背景色
    this.elevation,     // 对话框阴影
    this.semanticLabel,     // 对话框语义化标签
    this.shape,     // 对话框形状
}) 

      分析源码,AlertDialog 各个属性都比较清楚,灵活性较高;小菜由简易难逐渐尝试;

案例尝试

  1. 小菜尝试日常最常见的 Dialog
showDialog(context: context,
    builder: (context) {
      return AlertDialog(title: Text('AlertDialog', style: TextStyle(color: Colors.blueAccent)),
          content: Text('我是 AlertDialog 对话框!'),
          actions: <Widget>[
            FlatButton(child: Text("确定"), onPressed: () => Navigator.of(context).pop()),
            FlatButton(child: Text("取消"), onPressed: () => Navigator.of(context).pop())
          ]);
    });

  1. 小菜尝试对上述 Dialog 添加一些个性化;
  2. titleTextStylecontentTextStyle 不能改变标题和内容中已设置过的样式;
  3. shape 为对话框样式,如果设置为 CircleBorder 圆形背景效果时以宽高较小的尺寸为直径;
  4. actions 按钮个数最多可设置三个;
showDialog(context: context,
    builder: (context) {
      return AlertDialog(
          title: Text('AlertDialog', style: TextStyle(color: Colors.blueAccent)),
          titlePadding: EdgeInsets.all(20.0),
          titleTextStyle: TextStyle(color: Colors.pinkAccent, fontSize: 18.0, fontWeight: FontWeight.w600),
          content: Text('我是 AlertDialog 对话框!'),
          contentPadding: EdgeInsets.all(30.0),
          contentTextStyle: TextStyle(color: Colors.pinkAccent, fontSize: 16.0, fontWeight: FontWeight.w400),
          backgroundColor: Colors.greenAccent.withOpacity(0.7),
          elevation: 10.0,
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(20.0))),
          actions: <Widget>[
            FlatButton(child: Text("确定"), onPressed: () => Navigator.of(context).pop()),
            FlatButton(child: Text("取消"), onPressed: () => Navigator.of(context).pop())
          ]);
    });

  1. 小菜尝试 List AlertDialog
  2. Dialog 默认宽度是固定的,高度也有最大限度,若元素大小超过最大宽高则会溢出;
  3. AlertDialog 可以自由设置点击事件,并非只有 actions 设置;
showDialog(context: context,
    builder: (context) {
      return AlertDialog(
          title: Row(children: <Widget>[
            Image.asset('images/ic_launcher.png', scale: 2.0),
            Padding(child: Text('Alert List'), padding: EdgeInsets.only(left: 12.0)) ]),
          content: ListView.builder(itemCount: 30,
              itemBuilder: (BuildContext context, int index) {
                return ListTile(title: Text('当前 index = $index'), onTap: () => Navigator.of(context).pop(index));
              }),
          elevation: 10.0,
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(14.0))));
    });

  1. 小菜尝试自定义选择对话框;
showDialog(context: context,
    builder: (context) {
      return AlertDialog(
          title: Row(children: <Widget>[
            Image.asset('images/ic_launcher.png', scale: 2.0),
            Padding(child: Text('Alert 性别选择'), padding: EdgeInsets.only(left: 12.0)) ]),
          titleTextStyle: TextStyle(color: Colors.pinkAccent, fontSize: 18.0, fontWeight: FontWeight.w600),
          content: Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
            Row(children: <Widget>[
              Expanded(child: GestureDetector(child: Container(child: Image.asset('images/icon_type_boy.png'), width: 105.0),
                      onTap: () {
                        Navigator.of(context).pop();
                        Toast.show('AlertDialog Boy!', context, duration: Toast.LENGTH_SHORT,gravity: Toast.BOTTOM);
                      })),
              Expanded(child: GestureDetector(child: Container(child: Image.asset('images/icon_type_girl.png'), width: 105.0),
                      onTap: () {
                        Navigator.of(context).pop();
                        Toast.show('AlertDialog Girl!', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM);
                      })) ]),
            Row(children: <Widget>[
              Expanded(child: Center(child: Text('男生', style: TextStyle(color: Colors.blueAccent, fontSize: 16.0, fontWeight: FontWeight.w300)))),
              Expanded(child: Center(child: Text('女生'))) ])
          ]),
          contentTextStyle: TextStyle(color: Colors.pinkAccent, fontSize: 16.0, fontWeight: FontWeight.w300),
          contentPadding: EdgeInsets.fromLTRB(24.0, 10.0, 24.0, 0.0),
          elevation: 10.0,
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(14.0))),
          actions: <Widget>[
            FlatButton(child: Text("确定"), onPressed: () => Navigator.of(context).pop()),
            FlatButton(child: Text("取消"), onPressed: () => Navigator.of(context).pop())
          ]);
    });

SimpleDialog

源码分析

const SimpleDialog({
    Key key,
    this.title,     // 标题内容
    this.titlePadding = const EdgeInsets.fromLTRB(24.0, 24.0, 24.0, 0.0),  // 标题与周围边距
    this.children,   // 消息内容
    this.contentPadding = const EdgeInsets.fromLTRB(0.0, 12.0, 0.0, 16.0),      // 消息内容与周围边距
    this.backgroundColor,  // 对话框背景色
    this.elevation,     // 对话框阴影
    this.semanticLabel,     // 对话框语义化标签
    this.shape,     // 对话框形状
})

      分析源码,SimpleDialogAlertDialog 要简单,只是单独多一个 titlePadding;消息主体默认是 List;基本 SimpleDialog 可实现的效果 AlertDialog 均可实现;

案例尝试

  1. 小菜尝试最常见的选择对话框;小菜采用了 SimpleDialogOption 选项 Widget,默认是占满一行;
showDialog(context: context,
    builder: (context) {
      return SimpleDialog(
          title: Text('SimpleDialog', style: TextStyle(color: Colors.blueAccent)),
          children: <Widget>[
            Padding(child: Text('我是 SimpleDialog 对话框?'), padding: EdgeInsets.all(20.0)),
            SimpleDialogOption(child: Text('Yes'), onPressed: () => Navigator.pop(context)),
            SimpleDialogOption(child: Text('No'), onPressed: () => Navigator.pop(context))
          ]);
    });

  1. 小菜尝试 List SimpleDialog;需注意内容主体为 List 方式,使用 ListView 时要注意冲突;
showDialog(context: context,
    builder: (context) {
      return SimpleDialog(
          title: Row(children: <Widget>[
            Image.asset('images/ic_launcher.png', scale: 2.0),
            Padding(child: Text('Simple List'), padding: EdgeInsets.only(left: 12.0))
          ]),
          children: <Widget>[
            Container(height: 400.0,
                child: ListView.builder(itemCount: 30,
                    itemBuilder: (BuildContext context, int index) {
                      return ListTile(title: Text('当前 index = $index'), onTap: () => Navigator.of(context).pop(index));
                    }))],
          elevation: 10.0,
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(14.0))));
    });

  1. 小菜尝试自定义选择对话框;
showDialog(context: context, barrierDismissible: false,
    builder: (context) {
      return SimpleDialog(
          title: Row(children: <Widget>[
            Image.asset('images/ic_launcher.png', scale: 2.0),
            Padding(child: Text('Simple 性别选择'), padding: EdgeInsets.only(left: 12.0))
          ]),
          children: <Widget>[
            Row(children: <Widget>[
              Expanded(child: GestureDetector(child: Container(child: Image.asset('images/icon_type_boy.png'), width: 105.0),
                      onTap: () { Toast.show('SimpleDialog Boy!', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM); })),
              Expanded(child: GestureDetector(child: Container( child: Image.asset('images/icon_type_girl.png'), width: 105.0),
                      onTap: () { Toast.show('SimpleDialog Girl!', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM); })) ]),
            Padding(padding: EdgeInsets.symmetric(vertical: 14.0)),
                child: Row(children: <Widget>[
                  Expanded(child: Center(child: Text('男生', style: TextStyle(color: Colors.blueAccent, fontSize: 16.0, fontWeight: FontWeight.w300)))),
                  Expanded(child: Center(child: Text('女生', style: TextStyle( color: Colors.pinkAccent, fontSize: 16.0, fontWeight: FontWeight.w300))))
                ])],
          elevation: 10.0,
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(14.0))));
    });

UnconstrainedBox + SizedBox

      Flutter 的对话框中均未提供更改宽度的属性,高度可以自适应;小菜采用 UnconstrainedBox + SizedBox 可以实现对话框的宽度更改,首先用 UnconstrainedBox 抵消 showDialog 对宽度的限制;之后采用 SizedBox 设置对话框宽度;注意此时设置高度并没有效果依旧自适应;对话框宽度以 SizedBox 设置的 width 为主,child 的宽度无效;

showDialog(context: context, barrierDismissible: false,
    builder: (context) {
      return UnconstrainedBox(
          constrainedAxis: Axis.vertical,
          child: SizedBox(width: 180.0, height: 180.0,
              child: AlertDialog(content: Icon(Icons.ac_unit))));
    });

AboutDialog

      Flutter 提供了特殊的 AboutDialog,适用于应用说明或版本相关;

源码分析

const AboutDialog({
    Key key,
    this.applicationName,       // 应用名称
    this.applicationVersion,    // 版本说明
    this.applicationIcon,       // 应用图标
    this.applicationLegalese,   // 法律声明
    this.children,              // 消息内容
})

      分析源码可知,AboutDialog 继承自 AlertDialog 但对于自定义内容较少,对于 applicationName / applicationVersion / applicationLegalese 仅提供字符串方式,无法调整样式;且默认有版权和取消按钮;

案例尝试

      AboutDialog 类似于系统对话框,整体效果我们无法调整,对于主体内容 children 部分,与 SimpleDialog 类似,无法延迟加载模型组件,对于 ListView 等需明确高度;

showDialog(context: context,
    barrierDismissible: false,
    builder: (context) {
      return AboutDialog(
          applicationIcon: Container(child: Image.asset('images/icon_hzw02.jpg'), width: 80.0),
          applicationName: 'Flutter Dialog',
          applicationLegalese: '所有解释权归本人所有!',
          applicationVersion: 'V1.5.2',
          children: <Widget>[
            Padding(padding: EdgeInsets.only(top: 10.0), child: Text('1. AboutDialog!')),
            Padding(padding: EdgeInsets.only(top: 10.0), child: Text('2. SimpleDialog!')),
            Padding(padding: EdgeInsets.only(top: 10.0), child: Text('3. AlertDialog!'))
          ]);
    });

showAboutDialog

      Flutter 针对 AboutDialog 提供了简易的 showAboutDialog 方法;

源码分析

void showAboutDialog({
  @required BuildContext context,
  String applicationName,       // 应用名称
  String applicationVersion,    // 版本说明
  Widget applicationIcon,       // 应用图标
  String applicationLegalese,   // 法律声明
  List<Widget> children,        // 消息内容
})

      分析源码,showAboutDialog 是简化版的 AboutDialog,参数几乎全部一致;差别在于 showDialog 方式可以设置点击遮罩是否关闭对话框,而 showAboutDialog 不支持;

案例尝试

showAboutDialog(context: context,
    applicationIcon: Container(child: Image.asset('images/icon_hzw02.jpg'), width: 80.0),
    applicationName: 'Flutter Dialog',
    applicationLegalese: '所有解释权归本人所有!',
    applicationVersion: 'V1.5.2',
    children: <Widget>[
      Padding(padding: EdgeInsets.only(top: 10.0), child: Text('1. AboutDialog!')),
      Padding(padding: EdgeInsets.only(top: 10.0), child: Text('2. SimpleDialog!')),
      Padding(padding: EdgeInsets.only(top: 10.0), child: Text('3. AlertDialog!'))
    ]);

showDialog

源码分析

Future<T> showDialog<T>({
  @required BuildContext context,
  bool barrierDismissible = true,   // 遮罩层点击是否关闭对话框
  @Deprecated(
    'Instead of using the "child" argument, return the child from a closure '
    'provided to the "builder" argument. This will ensure that the BuildContext '
    'is appropriate for widgets built in the dialog.'
  ) Widget child,
  WidgetBuilder builder,
})

      分析源码,showDialog 采用 builder 方式取代 child 方式;而实际上 showDialog 是对 showGeneralDialog 的封装,默认的遮罩层颜色和渐进渐出的动画效果;

showGeneralDialog

源码分析

Future<T> showGeneralDialog<T>({
  @required BuildContext context,
  @required RoutePageBuilder pageBuilder,   // 对话框内部绘制
  bool barrierDismissible,      // 遮罩层点击是否关闭对话框
  String barrierLabel,      // 语义化标签
  Color barrierColor,       // 遮罩层颜色
  Duration transitionDuration,      // 动画持续时长
  RouteTransitionsBuilder transitionBuilder,    // 动画过程
})

      分析源码,showGeneralDialog 提供了更丰富的对话框设计;而实际也是对 Navigator.push 的封装;

案例尝试

      小菜重现以前博客中实现的简易对话框:由底部弹出且透明度由 0.0 到 1.0;测试 barrierColor 进入和退出时都是渐变符合动画效果,与采用 Navigator 打开页面动画方式不同;

showGeneralDialog(context: context,
    pageBuilder: (buildContext, _, __) {
      return Center(child: Container(
              height: 200.0, width: 200.0,
              decoration: BoxDecoration(color: Colors.greenAccent, borderRadius: BorderRadius.circular(5.0)),
              child: Icon(Icons.ac_unit, color: Colors.white)));
    },
    barrierDismissible: false,
    barrierColor: Colors.pink.withOpacity(0.2),
    transitionDuration: Duration(milliseconds: 1500),
    transitionBuilder: (context, animation, secondaryAnimation, child) {
      return SlideTransition(
          position: Tween<Offset>(begin: Offset(0.0, 1.0), end: Offset(0.0, 0.0)).animate(CurvedAnimation(parent: animation, curve: Curves.fastOutSlowIn)),
          child: FadeTransition(opacity: Tween(begin: 0.0, end: 1.0).animate(CurvedAnimation(parent: animation, curve: Curves.linear)),
              child: child));
    });


      虽然我们经常自定义 Dialog,但还是需要对系统基础的 Dialog 有所认知;以上是小菜的测试过程,如有错误请多多指导!

来源: 阿策小和尚

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