ScrollIntoView 不适用于 Touch

Question

所以我有一张地图，上面有许多 PushPins，右边的列表列出了所有 PushPins（使用相同的视图模型）

当我单击地图上的图钉时，我想将该项目滚动到列表中的视图中。

我目前在 Click 和 OnTouch 上使用此代码：

private void ScrollPushPin(Pushpin pushpin)
{
      ScrollViewer scrollViewer = GetScrollViewer(MyList) as ScrollViewer;
      scrollViewer.ScrollToBottom();
      var index = this.MyList.Items.IndexOf(pushpin);

      //index is never -1 so I would expect it to work?
      this.MyList.ScrollIntoView(pushpin); 
}

点击时：

void pp_MouseDown(object sender, MouseButtonEventArgs e)
{
    ScrollPushPin(sender as PushPin);
}

触摸时：

void pp_TouchDown(object sender, TouchEventArgs e)
{
    var pushpin = (Pushpin)sender;
    pushpin.CaptureTouch(e.TouchDevice);
}

void pp_TouchUp(object sender, TouchEventArgs e)
{
   var pushpin = (Pushpin)sender;
    if (pushpin != null && e.TouchDevice.Captured == pushpin)
    {
        pushpin.ReleaseTouchCapture(e.TouchDevice);
        ScrollPushPin(pushpin);
    }
}

虽然此代码在我用鼠标单击图钉时工作正常，但触摸事件不会将我的图钉滚动到视图中，我不明白为什么？

我也试过了：

this.MyList.Dispatcher.Invoke((Action)(() => this.MyList.ScrollIntoView(pushpin)));

和

this.MyList.ScrollIntoView(this.MyList.Items[val]);

Answer 1

所以不要问我为什么这样做，但在我的事件末尾添加 e.Handled = true 解决了问题：

void pp_TouchDown(object sender, TouchEventArgs e)
{
    var pushpin = (Pushpin)sender;
    pushpin.CaptureTouch(e.TouchDevice);
    e.Handled = true
}

void pp_TouchUp(object sender, TouchEventArgs e)
{
   var pushpin = (Pushpin)sender;
    if (pushpin != null && e.TouchDevice.Captured == pushpin)
    {
        pushpin.ReleaseTouchCapture(e.TouchDevice);
        ScrollPushPin(pushpin);
    }
    e.Handled = true
}

编辑

添加 e.Handled = true 导致了更多问题，所以我决定自己编写 ScrollIntoView

var val = this.MyList.Items.IndexOf(myObj);
if (val != -1)
{
    ScrollViewer scrollViewer = GetScrollViewer(MyList) as ScrollViewer;
    var itemHeight = scrollViewer.ExtentHeight / this.MyList.Items.Count;
    scrollViewer.ScrollToVerticalOffset(itemHeight * val);
}

//where
public static DependencyObject GetScrollViewer(DependencyObject o)
{
    if (o is ScrollViewer)
    { return o; }

    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(o); i++)
    {
        var child = VisualTreeHelper.GetChild(o, i);

        var result = GetScrollViewer(child);
        if (result == null)
        {
            continue;
        }
        else
        {
            return result;
        }
    }

    return null;
}

ScrollIntoView 不适用于 Touch

ScrollIntoView doesn't work with Touch

c#

scroll

listbox

touch

pushpin