AppBar 中的扩展小部件

Question

我有一个应用栏，我想在其中显示标题，然后在它旁边有一个凸起的按钮，该按钮会展开以填充剩余的水平区域 space。我试过这个的变体：

AppBar(
  title: Row(
    children: [
      Text("Select view"),
      // the row that follows is because it says Expanded widgets
      // should be put directly in Row or Column or Flex
      Padding(padding: EdgeInsets.only(left: 12.0), child: Row(children: [ 
        Expanded(child: RaisedButton(
          child: Text("view 1"),
          onPressed: () {
            // something
          },
        ),),
      ])),
    ]
  ),
);

为此，我收到以下错误：

I/flutter (26477): The following assertion was thrown during performLayout():

I/flutter (26477): The _ToolbarLayout custom multichild layout delegate forgot to lay out the following children:

I/flutter (26477): _ToolbarSlot.middle: RenderSemanticsAnnotations#6d937 NEEDS-LAYOUT NEEDS-PAINT

I/flutter (26477): _ToolbarSlot.middle: RenderSemanticsAnnotations#7fcd5 NEEDS-LAYOUT NEEDS-PAINT

I/flutter (26477): _ToolbarSlot.middle: RenderSemanticsAnnotations#f9a7a NEEDS-LAYOUT NEEDS-PAINT

I/flutter (26477): _ToolbarSlot.middle: RenderSemanticsAnnotations#ce1f2 NEEDS-LAYOUT NEEDS-PAINT

I/flutter (26477): Each child must be laid out exactly once.

我尝试的所有其他事情也抛出了一些断言异常。我真的不在乎我是怎么做的，我只想有两个小部件 - 标题和旁边的 RaisedButton 填充应用栏中 space 的其余部分。

Answer 1

只需删除包含 RaisedButton

的行

 appBar: AppBar(
          title: Row(children: [
            Text("Select view"),
            Expanded(
              child: RaisedButton(
                child: Text("view 1"),
                onPressed: () {
                  // something
                },
              ),
            ),
          ]),
        ),

AppBar 中的扩展小部件

Expanded widget in AppBar

flutter

flutter-layout