颤动滚动到列表中的特定项目 [英] Flutter scroll to specific item in list

问题描述

我在Flutter中有一个ListView，允许用户动态添加项目.添加项目后，我希望列表滚动到添加的项目.我在ListView上附加了ScrollController，因此可以使用animateTo滚动，但是我不确定如何确定向下滚动的偏移量.我有这样的东西:

I have a ListView in Flutter that I allow users to dynamically add items to. After adding an item I would like for the list to scroll to the item that was added. I've attached a ScrollController to the ListView so I could use animateTo to scroll, but I'm unsure of how to determine the offset to scroll down to. I had something like this:

_scrollController.animateTo(
    addedIndex.toDouble() * 100,
    curve: Curves.easeOut,
    duration: const Duration(milliseconds: 300),
);

其中，addedIndex是将该项目添加到列表的顺序.但这并不是很有效，并且似乎只有在我能弄清楚列表中每个项目的高度时才能起作用，但我不确定该怎么做.有没有一种更好的方法可以准确地找到要滚动到的位置?

where addedIndex is the order that the item was added to the list. That doesn't quite work though, and seems like it would only work if I could figure out the height of each item in the list, which I'm not sure how to do. Is there a better way to figure out exactly where to scroll to?

推荐答案

首先，创建一个新的globalKey.

First, create a new globalKey.

final GlobalKey globalKey = GlobalKey();

第二，将globalKey添加到要移动到的小部件.

Second, add globalKey to the widget you want to move to.

然后，基于globalKey获取窗口小部件的位置.

Then, get the widget location based on globalKey.

RenderBox box = globalKey.currentContext.findRenderObject();
Offset offset = box.localToGlobal(Offset.zero);

获得的窗口小部件位置是相对于当前页面显示状态的，窗口小部件的高度包括状态栏和AppBar的高度.

The widget position obtained is relative to the current page display status , widget height includes status bar and AppBar height.

状态栏高度

import 'dart:ui’; 
MediaQueryData.fromWindow(window).padding.top

AppBar高度56.0

AppBar height 56.0

scrollView的偏移量需要添加

scrollView's offset need to add

double animationHeight = _controller.offset + offset.dy - MediaQueryData.fromWindow(window).padding.top - 56.0;
_controller.animateTo(animationHeight, duration: Duration(milliseconds: 500), curve: Curves.decelerate);

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希望它会对您有所帮助.

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hope it will help you.

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