如何在 Flutter 中对齐单个小部件? [英] How to align single widgets in Flutter?

问题描述

我想在其父级中对齐 Flutter 小部件.我知道我可以通过将小部件包装在一个中心小部件中来使其居中.

 中心(孩子:文本(小部件")，)

但是如何将其与右侧、底部、顶部中间等对齐?

注意事项:

我说的是一个孩子，而不是一行或一列中的多个孩子.请参阅这些 SO 问题:

• 您不仅限于这些地点.您可以在任何地方对齐您的小部件.通过指定一个 x,y 对，其中 (0,0) 是视图的中心，边缘是围绕它的 1.0 单位.也许图片会有所帮助:

  where 为任何相对位置 (x,y)

  • Alignment.topLeft 是 Alignment(-1.0, -1.0)
  • Alignment.topCenter 是 Alignment(0.0, -1.0)
  • Alignment.topRight 是 Alignment(1.0, -1.0)
  • Alignment.centerLeft 是 Alignment(-1.0, 0.0)
  • Alignment.center 是 Alignment(0.0, 0.0)
  • Alignment.centerRight 是 Alignment(1.0, 0.0)
  • Alignment.bottomLeft 是 Alignment(-1.0, 1.0)
  • Alignment.bottomCenter 是 Alignment(0.0, 1.0)
  • Alignment.bottomRight 是 Alignment(1.0, 1.0)

  注意图中的对齐方式 (x,y) 不需要在 [-1, +1] 范围内.对齐方式 (1,2) 表示它位于小部件的右侧，再低于小部件的一半高度.

  这是自定义对齐位置的示例.

  对齐(对齐:对齐(0.7，-0.5)，孩子:文本(小部件")，)

  补充代码

  这是用于制作上述示例的 main.dart 代码，以方便您进行剪切和粘贴.

  import 'package:flutter/material.dart';void main() =>运行应用程序(我的应用程序())；class MyApp 扩展 StatelessWidget {@覆盖小部件构建(BuildContext 上下文){返回 MaterialApp(主页: 脚手架(应用栏:应用栏()，正文:myLayoutWidget()，),);}}小部件 myLayoutWidget() {返回对齐(对齐:对齐(0.7，-0.5)，孩子:文本("小部件",样式:TextStyle(字体大小:30)，),);}

  I want to align a Flutter widget within its parent. I know that I can center a widget by wrapping it in a Center widget.

    Center(
      child: Text("widget"),
    )
  

  But how do I align it to the right, bottom, top middle, etc?

  Notes:

  I am talking about a single child, not multiple children in a Row or Column. See these SO questions:

  • Align Text widgets in a row widget
  • FLUTTER | Right Align not working

  This one is on the right track but I am trying to make a more cannonical question:

  • How to left align the OutlineButton icon in Flutter

  解决方案

  How to align widgets

  To align a child widget within its parent you use the Align widget. If you know how to use the Center widget then you are the right track because Center is just a special case of Align.

  Wrap the widget you wish to align with the Align widget and set its alignment property. For example, this would align a text widget to the middle right of the parent.

  Align(
    alignment: Alignment.centerRight,
    child: Text("widget"),
  )
  

  Other options are

  • Alignment.topLeft
  • Alignment.topCenter
  • Alignment.topRight
  • Alignment.centerLeft
  • Alignment.center
  • Alignment.centerRight
  • Alignment.bottomLeft
  • Alignment.bottomCenter
  • Alignment.bottomRight

  Here is what that looks like:

  You are not limited to these locations. You can align your widget anywhere. by specifying an x,y pair, where (0,0) is the center of the view and the edges are 1.0 unit around it. Maybe an image would help:

  where for any relative position (x,y)

  • Alignment.topLeft is Alignment(-1.0, -1.0)
  • Alignment.topCenter is Alignment(0.0, -1.0)
  • Alignment.topRight is Alignment(1.0, -1.0)
  • Alignment.centerLeft is Alignment(-1.0, 0.0)
  • Alignment.center is Alignment(0.0, 0.0)
  • Alignment.centerRight is Alignment(1.0, 0.0)
  • Alignment.bottomLeft is Alignment(-1.0, 1.0)
  • Alignment.bottomCenter is Alignment(0.0, 1.0)
  • Alignment.bottomRight is Alignment(1.0, 1.0)

  Notice in the image that the alignment (x,y) doesn't need to be within the range [-1, +1]. The alignment (1,2) means it is at the right side of the widget and below the widget half again as much as its height.

  Here is an example of a custom alignment position.

  Align(
    alignment: Alignment(0.7, -0.5),
    child: Text("widget"),
  )
  

  Supplemental code

  Here is the main.dart code used to make the above examples for your cut-and-paste convenience.

  import 'package:flutter/material.dart';
  
  void main() => runApp(MyApp());
  
  class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        home: Scaffold(
          appBar: AppBar(),
          body: myLayoutWidget(),
        ),
      );
    }
  }
  
  Widget myLayoutWidget() {
    return Align(
      alignment: Alignment(0.7, -0.5),
      child: Text(
        "widget",
        style: TextStyle(fontSize: 30),
      ),
    );
  }
  

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