如何将一列小部件紧紧包裹在卡片中？

Question

我的应用程序页面仅包含一个 Card，其中包含一个 Column，最后是一个 MaterialList。即使我的列表只有一两个项目，卡片也会将其垂直 space 扩展到屏幕底部，而不是停在列表项目的末尾。 Column documentation 表明这是正常的列行为 ("Layout each child a null or zero flex factor (e.g., those that are not Expanded) with unbounded vertical constraints")。我认为将列表包装在 Flexible 中可能会达到我想要的效果，但是当我尝试时出现以下错误：

RenderFlex children have non-zero flex but incoming height constraints are unbounded.
I/flutter (11469): When a column is in a parent that does not provide a finite height constraint, for example if it is
I/flutter (11469): in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
I/flutter (11469): flex on a child (e.g. using a Flexible) indicates that the child is to expand to fill the remaining
I/flutter (11469): space in the vertical direction.
I/flutter (11469): These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
I/flutter (11469): cannot simultaneously expand to fit its parent.

我显然误解了此布局的工作原理。

这是我现在作为此页面 Scaffold 正文的示例代码：

new Container(
// Outer container so we can set margins and padding for the cards
// that will hold the rest of the view.
alignment: FractionalOffset.topCenter,
margin: new EdgeInsets.only(top: style.wideMargin),
padding: new EdgeInsets.symmetric(horizontal: style.defaultMargin),
child: new Card(
  child: new Column(
    children: [
      new CustomHeader(), // <-- a Row with some buttons in it
      new Divider(),
      new MaterialList(
        type: MaterialListType.twoLine,
        children: listItems, // <-- a list of custom Rows
      ),
    ],
  ),
),

)

我怎样才能拥有一张紧密包裹 Column 小部件的卡片？

Answer 1

默认情况下，Column 展开以填充最大垂直 space。您可以通过将 mainAxisSize 属性设置为 MainAxisSize.min 来更改此行为，这会导致 Column 仅占用它需要的最小垂直量 space适合其 children.

Answer 2

如果有人想缩小列表，Wrap widget 可能会派上用场，这与 @亚当回答

body: Container(
        child: Card(
          child: Wrap(
            direction: Axis.vertical,
            spacing: 10,
            children: <Widget>[
              Text('One'),
              Text('Two'),
              Text('Three'),
              Text('Four'),
            ],
          ),
        ),
      ),

但是如果您为 Axis.vertical 添加列并为 Axis.Horizontal 添加行，则此换行可以完成行和列的工作。 您还可以为列和行中缺少的所有中间小部件添加相等的间距

如何将一列小部件紧紧包裹在卡片中？

How can I tightly wrap a Column of widgets inside a Card?

flutter