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我有一个包装树视图的滚动查看器。

我以编程方式填充树视图(未绑定),并将树视图扩展为预定的树视图项。这一切都很好。

我的问题是,当树扩展时,我希望作为树视图的父级的滚动视图滚动到我刚刚扩展的树视图项。有任何想法吗?- 请记住,树视图每次展开时可能没有相同的结构,因此排除了仅存储当前滚动位置并重置为...

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2 回答 2

4

我遇到了同样的问题,TreeView 没有滚动到所选项目。

我所做的是,在将树扩展到选定的 TreeViewItem 之后,我调用了一个 Dispatcher Helper 方法来允许 UI 更新,然后在选定的项目上使用 TransformToAncestor 来找到它在 ScrollViewer 中的位置。这是代码:

    // Allow UI Rendering to Refresh
    DispatcherHelper.WaitForPriority();

    // Scroll to selected Item
    TreeViewItem tvi = myTreeView.SelectedItem as TreeViewItem;
    Point offset = tvi.TransformToAncestor(myScroll).Transform(new Point(0, 0));
    myScroll.ScrollToVerticalOffset(offset.Y);

这是 DispatcherHelper 代码:

public class DispatcherHelper
{
    private static readonly DispatcherOperationCallback exitFrameCallback = ExitFrame;

    /// <summary>
    /// Processes all UI messages currently in the message queue.
    /// </summary>
    public static void WaitForPriority()
    {
        // Create new nested message pump.
        DispatcherFrame nestedFrame = new DispatcherFrame();

        // Dispatch a callback to the current message queue, when getting called,
        // this callback will end the nested message loop.
        // The priority of this callback should be lower than that of event message you want to process.
        DispatcherOperation exitOperation = Dispatcher.CurrentDispatcher.BeginInvoke(
            DispatcherPriority.ApplicationIdle, exitFrameCallback, nestedFrame);

        // pump the nested message loop, the nested message loop will immediately
        // process the messages left inside the message queue.
        Dispatcher.PushFrame(nestedFrame);

        // If the "exitFrame" callback is not finished, abort it.
        if (exitOperation.Status != DispatcherOperationStatus.Completed)
        {
            exitOperation.Abort();
        }
    }

    private static Object ExitFrame(Object state)
    {
        DispatcherFrame frame = state as DispatcherFrame;

        // Exit the nested message loop.
        frame.Continue = false;
        return null;
    }
}
于 2009-12-17T15:46:24.560 回答
2

Jason 的 ScrollViewer 技巧是将 TreeViewItem 移动到特定位置的好方法。

但是有一个问题:在 MVVM 中,您无法访问视图模型中的 ScrollViewer。无论如何,这是一种方法。如果你有一个 TreeViewItem,你可以沿着它的可视化树向上走,直到你到达嵌入的 ScrollViewer:

// Get the TreeView's ScrollViewer
DependencyObject parent = VisualTreeHelper.GetParent(selectedTreeViewItem);
while (parent != null && !(parent is ScrollViewer))
{
    parent = VisualTreeHelper.GetParent(parent);
}
于 2010-09-21T20:33:26.073 回答