查找WPF控件中视 [英] Find WPF Controls in Viewport

问题描述

更新：

这可能是一个简单或复杂的问题，但在WPF中，我有我填了的的DataTemplate 的列表框从列表中。

This may be an easy or a complex question, but in wpf, I have a listbox that I fill in with a datatemplate from a list.

有没有办法找出如果一个特定的的DataTemplate项目的是在视口中也就是说，我已滚动到它的位置，它是可见的？

Is there a way to find out if a particular datatemplate item is in the viewport ie, I have scrolled to its position and it is viewable?

目前我迷上到listbox_ScrollChanged事件，这一点让我ScrollChangedEventArgs，但我还没有找到合适的物业...

Currently I hooked into the listbox_ScrollChanged event, and this gives me the ScrollChangedEventArgs, but I haven't found the right property...

任何帮助将是非常美联社preciated，谢谢！

Any help would be much appreciated, thanks!

推荐答案

请参阅<一href="http://stackoverflow.com/questions/1517743/in-wpf-how-can-i-determine-whether-a-control-is-visible-to-the-user">this问题

有关具体列表框，你可以做到这一点。

For a ListBox in specific you can do this

private bool IsControlVisibleToUser(Control control)
{
    ListBoxItem listBoxItem =
        listBox.ItemContainerGenerator.ContainerFromItem(control) as ListBoxItem;
    if (listBoxItem != null)
    {
        return IsUserVisible(listBoxItem, listBox);
    }
    return false;
}

和从我联系问题的方法

private bool IsUserVisible(FrameworkElement element, FrameworkElement container)
{
    if (!element.IsVisible)
        return false;
    Rect bounds = element.TransformToAncestor(container).TransformBounds(new Rect(0.0, 0.0, element.ActualWidth, element.ActualHeight));
    Rect rect = new Rect(0.0, 0.0, container.ActualWidth, container.ActualHeight);
    return rect.Contains(bounds.TopLeft) || rect.Contains(bounds.BottomRight);
} 

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