WPF拖放轮播

Question

I´m new in WPF and I´m trying to do a drag and drop with carousel.

First, I´ve seen a example with listview. The example is this: http://wpftutorial.net/DragAndDrop.html , I´ve tried it and it is correct.

But my problem is that when I want to use a Carousel I don´t know to get the item selected when I do a click in the element I want to move. In the example is this function:

private void List_MouseMove(object sender, MouseEventArgs e)
{
    // Get the current mouse position
    Point mousePos = e.GetPosition(null);
    Vector diff = startPoint - mousePos;

    if (e.LeftButton == MouseButtonState.Pressed &&
        Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
        Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance )
    {
        // Get the dragged ListViewItem
        ListView listView = sender as ListView;
        ListViewItem listViewItem = 
            FindAnchestor<ListViewItem>((DependencyObject)e.OriginalSource);

        // Find the data behind the ListViewItem
        Contact contact = (Contact)listView.ItemContainerGenerator.
            ItemFromContainer(listViewItem);

        // Initialize the drag & drop operation
        DataObject dragData = new DataObject("myFormat", contact );
        DragDrop.DoDragDrop(listViewItem, dragData, DragDropEffects.Move);
    } 
}

I´m using this code in xaml file:

<dxca:CarouselItemsControl x:Name="_carouselName" 
                                    PreviewMouseLeftButtonDown="List_PreviewMouseLeftButtonDown" 
                                    PreviewMouseMove="List_MouseMove" >

I need to get the object I want to drag, in the example is contact.

// Find the data behind the ListViewItem
Contact contact = (Contact)listView.ItemContainerGenerator.ItemFromContainer(listViewItem);

Any idea?

Answer 1

If you're new to WPF and you're attempting something as tricky as this, then you're either very clever or very... well... something else.

Try something like this:

private void ListView_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    UIElement uiElement = (UIElement)e.Source;
    HitTestResult hitTestResult = VisualTreeHelper.HitTest(uiElement,  
e.GetPosition(null));
    ListBoxItem listBoxItemUnderMouse = hitTestResult.VisualHit.
GetParentOfType<ListBoxItem>();
    if (listBoxItemUnderMouse != null)
    {
        // Do your stuff here
    }
}        

GetParentOfType is a static extension helper method that I created:

public static T GetParentOfType<T>(this DependencyObject element) where T : DependencyObject
{
    Type type = typeof(T);
    if (element == null) return null;
    DependencyObject parent = VisualTreeHelper.GetParent(element);
    if (parent == null && ((FrameworkElement)element).Parent is DependencyObject) 
parent = ((FrameworkElement)element).Parent;
    if (parent == null) return null;
    else if (parent.GetType() == type || parent.GetType().IsSubclassOf(type)) return 
parent as T;
    return GetParentOfType<T>(parent);
}