Scroll to selected Treeviewitem in scroll

Question

I have a scrollviewer wrapping a treeview.

I fill the tree image programmatically (it is not attached) and expands the tree structure to the specified tree element. Everything works perfectly.

My problem is that when the tree expands, I need the scrollview to give birth to the tree in order to scroll to the tree that I just expanded. Any ideas? - keep in mind that the tree structure may not have the same structure every time it expands, therefore it excludes just saving the current scroll position and its reselling ...

Answer 1

, TreeView .

, TreeViewItem Dispatcher Helper, , TransformToAncestor , ScrollViewer. :

    // 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);

DispatcherHelper:

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;
    }
}

Answer 2

Jason ScrollViewer - TreeViewItem .

: MVVM ScrollViewer . , . TreeViewItem, , ScrollViewer:

// Get the TreeView ScrollViewer
DependencyObject parent = VisualTreeHelper.GetParent(selectedTreeViewItem);
while (parent != null && !(parent is ScrollViewer))
{
    parent = VisualTreeHelper.GetParent(parent);
}