Listbox Click and Drag

Question

I have a Listbox a MainControl and 4 PreviewControls. I would like when i click an item from the listbox that the mainControl changes (This happens). But i would like to add a dragg behavior to the listboxitems so i can drag a listboxitem to one of the previewControls. I tried this but when i try to drag the listboxitem the selectionchanged event is always fired.

So i would like that when i do MouseLeftDown and move the listboxitem, Do drag. And When Click or MouseLefUp (selectionchanged) occurs the MainControl changes.

I tried this but PreviewMouseLeftButtonDown event again the other events aren't executed.

private void lstCameras_PreviewMouseLeftButtonDown_1(object sender, MouseButtonEventArgs e)
    {
        startPoint = e.GetPosition(null);
        if (!Test) e.Handled = true;
        else
        {
            Test = false;
        }
        Console.WriteLine("lstCameras_PreviewMouseLeftButtonDown_1 Handled = " + e.Handled);
    }

    private void lstCameras_PreviewMouseUp_1(object sender, MouseButtonEventArgs e)
    {
        Console.WriteLine("lstCameras_MouseUp_1");
        if (!Test)
        {
            Test = true;
    lstCameras.RaiseEvent(new MouseButtonEventArgs(Mouse.PrimaryDevice, Environment.TickCount, MouseButton.Left) { RoutedEvent = ListBox.PreviewMouseLeftButtonDownEvent });
        }
        else
        {
            Test = false;
        }
        Console.WriteLine("end lstCameras_MouseUp_1 Test = " + Test);
    }

Both the scenario and the question is hard to discern from the way this question is written. Please consider restating / rephrasing your question and be sure that both the scenario and the question itself are very clear. — Sam

Sam_vdd Sam_vdd · Accepted Answer · 2013-02-26T14:43:22

Don't know if it is the best way but it works.

private object GetDataFromListBox(ListBox source, Point point)
    {
        DependencyObject element = source.InputHitTest(point) as DependencyObject;
        if (element != null)
        {
            object data = DependencyProperty.UnsetValue;
            while (data == DependencyProperty.UnsetValue)
            {
                data = source.ItemContainerGenerator.ItemFromContainer(element);
                if (data == DependencyProperty.UnsetValue)
                {
                    element = (DependencyObject)VisualTreeHelper.GetParent(element);
                }
                if (element == source)
                {
                    return null;
                }
            }
            if (data != DependencyProperty.UnsetValue)
            {
                return data;
            }
        }
        return null;
    }
    private void lstCameras_PreviewMouseMove_1(object sender, MouseEventArgs e)
    {
        Point mousePos = e.GetPosition(null);
        Vector diff = startPoint - mousePos;

        if (e.LeftButton == MouseButtonState.Pressed && this.DataContext != null &&
            (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
            Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
        {
            ListBox parent = (ListBox)sender;
            Item data = (Item)GetDataFromListBox(parent, e.GetPosition(parent));

            if (data != null)
            {
                DataObject dragData = new DataObject(typeof(Item), data);
                DragDrop.DoDragDrop(this, dragData, DragDropEffects.All);
            }
        }
    }

    private void lstCameras_PreviewMouseDown_1(object sender, MouseButtonEventArgs e)
    {
        ListBox parent = (ListBox)sender;
        Item data = (Item)GetDataFromListBox(parent, e.GetPosition(parent));

        if (data != null )
        {
            startPoint = e.GetPosition(null);
            e.Handled = true;
        }
    }

    private void lstCameras_PreviewMouseUp_1(object sender, MouseButtonEventArgs e)
    {
        ListBox parent = (ListBox)sender;
        Item data = (Item)GetDataFromListBox(parent, e.GetPosition(parent));

        if (data != null)
        {
            lstCameras.SelectedItem = data;
        }
    }

Listbox Click and Drag

2 Answers