Question

I am using ListView.buildler to layer Widget, into a vertical scroll. My only issue with this approach is that when the scroll reaches the end of my content. It wraps back to the top automatically. Currently I have this:

    new ListView.builder(
    scrollDirection: Axis.vertical,
    key: new Key(randomString(20)),
    reverse: false,
    primary: true,
    itemBuilder: (BuildContext context, int index) {
        return new Column(
        children: <Widget>[
            new Padding(
            padding: _bookPadding,
            child: new Container(
                width: 106.0,
                height: 162.0,
                child: new FadeInImage(
                    placeholder: new AssetImage('assets/loading.gif'),
                    image: this.book.cover)
            ),
            ),
            const Divider(),
            new Padding(
                padding: _bookPadding,
                child: new Text(
                    this.book.bookName,
                    style: getTextStyle())),
            const Divider(),
            new Padding(
            padding: _bookPadding,
            child: new Text(
                'By ' + this.book.author,
                style: getTextStyle(), ),
            ),
           ....

Is it possible to set ListView.builder to no-wrap when it reaches the end?

Answer 1

这最终很容易。不确定我是如何从文档中错过它的，我需要添加的是Item count = non-null。就我而言，由于我在单个Column小部件中构建我的所有内容，在list-view构建器中，这就是我的构建器的样子：

new ListView.builder(
    scrollDirection: Axis.vertical,
    key: new Key(randomString(20)),
    primary: true,
    itemCount: 1,
    itemBuilder: (BuildContext context, int index) {
        return new Column(
        children: <Widget>[ .....

如果它是一个糟糕的模式，我确实想知道这个实现。 ListView.Builder是否仍会渲染Component Column的每个嵌套子元素，因为Column的每个子元素都可见？

从文档：“创建按需创建的可滚动，线性的小部件数组。此构造函数适用于具有大量（或无限）子项数的列表视图，因为仅为那些实际可见的子项调用构建器。“

Answer 2

您可以跳过很多代码。有时itemBuilder非常好，特别是当你有很多小部件并且可以通过索引轻松识别你的项目时，你也可以直接使用这些孩子。 ListView documentation：

中的一个示例

new ListView(
  shrinkWrap: true,
  padding: const EdgeInsets.all(20.0),
  children: <Widget>[
    const Text('I\'m dedicating every day to you'),
    const Text('Domestic life was never quite my style'),
    const Text('When you smile, you knock me out, I fall apart'),
    const Text('And I thought I was so smart'),
  ],
)

Flutter ListView.builder creates an infinite scroll. How can I set it to stop at the end of content?

2 个答案: