Question

我想使用 Layout Builder 测量 SliverAppBar 的高度，然后在获得 SliverAppBar 高度的高度后，使用ScrollController。

我有一些类似这样的代码：

CustomScrollView(
          controller: _scrollController,
          slivers: <Widget>[
            LayoutBuilder(
              builder: (context, constraint) {
                message = constraint.biggest.height.toString();
                return SliverAppBar(
                  floating: false,
                  pinned: true,
                  expandedHeight: ScreenUtil.getInstance().setHeight(250),
                  leading: Container(
                    color: Colors.blue.withOpacity(.5),
                    child: IconButton(
                      icon: Icon(Icons.arrow_back),
                      onPressed: () => Navigator.pop(context),
                    ),
                  ),
                  flexibleSpace: FlexibleSpaceBar(
                    // titlePadding: EdgeInsets.zero,
                    title: Container(
                      width: ScreenUtil.getInstance().setWidth(250),
                      child: Text(
                        message ?? "Null",
                        style: ResponsiveUI.textNamaWartawanStylWhite,
                        overflow: TextOverflow.ellipsis,
                      ),
                    ),
                    background: Container(
                      child: CachedNetworkImage(
                        fit: BoxFit.cover,
                        imageUrl:
                            "${Urls.BASE_API_IMAGE}/wartawan/${widget.gambarWartawan}",
                      ),
                    ),
                  ),
                  actions: <Widget>[
                    Container(
                      color: Colors.blue.withOpacity(.5),
                      child: IconButton(
                        icon: Icon(Icons.more_horiz),
                        onPressed: () => "",
                      ),
                    ),
                  ],
                );
              },
            ),
          ],
        ),

但是我得到这个错误：

The following assertion was thrown building Listener:
A RenderViewport expected a child of type RenderSliver but received a child of type _RenderLayoutBuilder.

RenderObjects expect specific types of children because they coordinate with their children during layout and paint. For example, a RenderSliver cannot be the child of a RenderBox because a RenderSliver does not understand the RenderBox layout protocol.
The RenderViewport that expected a RenderSliver child was created by: Viewport ← IgnorePointer-[GlobalKey#4f27a] ← Semantics ← _PointerListener ← Listener ← _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#ed3fa] ← _PointerListener ← Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#c7130] ← RepaintBoundary ← ⋯
The _RenderLayoutBuilder that did not match the expected child type was created by: LayoutBuilder ← Viewport ← IgnorePointer-[GlobalKey#4f27a] ← Semantics ← _PointerListener ← Listener ← _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#ed3fa] ← _PointerListener ← Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#c7130] ← ⋯
User-created ancestor of the error-causing widget was
    CustomScrollView 
When the exception was thrown, this was the stack
#0      ContainerRenderObjectMixin.debugValidateChild.<anonymous closure> 
#1      ContainerRenderObjectMixin.debugValidateChild

您能帮我解决我的案件吗？谢谢。

Answer 1

您不能在CustomScrollView中放置非银条。您可能需要将layoutbuilder放置在FlexibleSpace的背景内。

Answer 2

试试 SliverLayoutBuilder 小部件。

说明：

您不能将非细长小部件（例如 LayoutBuilder）放置在将细长部件作为子部件的小部件（例如 CustomScrollView）内。

例如，当您想向条子添加填充时，您应该使用 SliverPadding 小部件，而不是普通的 Padding 小部件。类似地，还有一个 LayoutBuilder 的银色版本，称为 SliverLayoutBuilder。

Flutter：LayoutBuilder中的SliverAppBar

2 个答案: