wpf 中使用ScrollViewer 时鼠标滑轮按照内容进行滚动

xaml:

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1 2	<ScrollViewer x:Name="sv"   CanContentScroll="False" PreviewMouseWheel="ScrollViewer_PreviewMouseWheel"   > </ScrollViewer>

后台：

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private void ScrollViewer_PreviewMouseWheel(object sender, MouseWheelEventArgs e)        {            ScrollViewer viewer = sv;  //sv 为Scrollview的名字，在Xaml文件中定义。            if (viewer == null) return;            double num = Math.Abs((int)(e.Delta / 2));            double offset = 0.0;            if (e.Delta > 0)            {                offset = Math.Max((double)0.0, (double)(viewer.VerticalOffset - num));//viewer.VerticalOffset获取包含滚动内容的垂直偏移量的值。            }            else            {                offset = Math.Min(viewer.ScrollableHeight, viewer.VerticalOffset + num);            }            if (offset != viewer.VerticalOffset)            {                viewer.ScrollToVerticalOffset(offset);//将 ScrollViewer 内的内容滚动到指定的垂直偏移量位置。                e.Handled = true;            }          }