算算水平偏移滚动的ListView到的SelectedItem中心 [英] Calculate Horizontal Offset to scroll ListView to the center of the SelectedItem

问题描述

我建立一个照片应用程序，使用 FlipView 和的ListView 为分页。
当我点击了的ListView缩小图片它显示我在 FlipView 相同的画面。当我刷卡进入 FlipView ，选择将选择的ListView相同的图片任何照片。这是通过添加到两者完成：

I am building a photo application, using a FlipView and a listView as a Pagination. When I click on the thumbnail picture in the ListView it shows me the same picture in the FlipView. And when I swipe into the FlipView, any photo selected will select the same picture in the ListView. This is done by adding to both of them:

到的ListView ：

SelectedIndex="{Binding Path=SelectedIndex, ElementName=flipView1, Mode=TwoWay}

和对 FlipView ：

SelectedIndex="{Binding Path=SelectedIndex, ElementName=listView1, Mode=TwoWay}

和给我增加了的ListView的SelectionChanged 事件：

 if (e.AddedItems.Count > 0)
        listView1.ScrollIntoView(e.AddedItems.First(), ScrollIntoViewAlignment.Leading);

我唯一的问题是，当我刷卡 FlipView ，所需的图片中选择了的ListView 但的ScrollViewer 不是滚动到它。我试着用 WinRTXamlToolkit 来改变位置的的ScrollViewer ：

My only problem is that when I swipe the FlipView, the desired picture is selected in the ListView but the ScrollViewer is not scrolled to it. I tried using WinRTXamlToolkit to change the position of the ScrollViewer:

private void pageRoot_Loaded()
        {
            // count number of all items
            int itemCount = this.listView1.Items.Count;
            if (itemCount == 0)
                return;

            if (listView1.SelectedIndex >= itemCount)
                listView1.SelectedIndex = itemCount - 1;

            // calculate x-posision of selected item
            double listWidth = this.listView1.ActualWidth;
            double xPos = (listWidth / itemCount) * listView1.SelectedIndex;

            // scroll
            var scrollViewer2 = listView1.GetFirstDescendantOfType<ScrollViewer>();
            if (scrollViewer2 != null)
                scrollViewer2.ChangeView(xPos, 0.0, 1);
        }

首次 listWidth 是 1600.0 然后把它变成 0.0 所有的时间，这给 XPOS = 0.0 ！

The first time listWidth is 1600.0 and then it becomes 0.0 all the time, which gives xPos = 0.0!

我该如何解决这个问题？

How can I fix this?

推荐答案

ListView.ScrollIntoView（）应该工作。有可能是与调用一个方法来滚动的ScrollViewer问题，而它已经滚动，虽然。我会尝试用摆弄ScrollViewer.InvalidateScrollInfo（）这可能会加快速度。否则 - 你可以尝试处理 ViewChanging / ViewChanged 事件来看看它的滚动和尝试一起使用该信息与 ScrollViewerViewChangedEventArgs.IsIndeterminate 来链的调用。

ListView.ScrollIntoView() should work. There might be issues with calling a method to scroll a ScrollViewer while it's already scrolling though. I would try fiddling with ScrollViewer.InvalidateScrollInfo() which might speed it up. Otherwise - you could try handling the ViewChanging/ViewChanged events to see if it's scrolling and try to use that information together with ScrollViewerViewChangedEventArgs.IsIndeterminate to chain the calls.

还检查我的回答这个问题：
<一href=\"http://stackoverflow.com/questions/22595675/centering-selected-item-in-a-scroll-viewer\">Centering在滚动查看器选择的项目

Also check my answer to this question: Centering selected item in a scroll viewer

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