Question

我在单选模式下运行WPF ListBox。我正在添加拖放以移动项目。目前ListBox选择响应左按钮然后按下左按钮鼠标移动。因此，在等待MinimumVerticalDragDistance开始拖动操作后，可以选择其他项目。拖动未选择的原始项目或拖动新选定的项目会让人感到困惑。在xxx _ MouseMove或xxx _ PreviewMouseMove中添加'e.Handled = true'不会执行任何操作。由于鼠标左移按钮而导致抑制此选择的任何想法？

Answer 1

我提出的最好的方法是在IsMouseCapturedChanged事件中取消ListBox的“通过拖动选择”。

    public partial class MainWindow : Window
{
    Rect? dragSourceGestureRect;
    bool busy;

    public MainWindow()
    {
        InitializeComponent();

        listBox.ItemsSource = Enumerable.Range(1, 9);

        listBox.PreviewMouseLeftButtonDown += listBox_PreviewMouseLeftButtonDown;
        listBox.IsMouseCapturedChanged += listBox_IsMouseCapturedChanged;
        listBox.MouseMove += listBox_MouseMove;
    }

    void listBox_IsMouseCapturedChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        if (busy)
            return;

        if (!listBox.IsMouseCaptured)
            dragSourceGestureRect = null;

        else if (dragSourceGestureRect.HasValue)
        {
            busy = true;
            {
                //tell the ListBox to cancel it's "Selection by dragging"
                listBox.ReleaseMouseCapture();
                //Now recapture the mouse for canceling my dragging
                listBox.CaptureMouse();
            }
            busy = false;
        }
    }

    void listBox_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        var center = e.GetPosition(listBox);
        dragSourceGestureRect = new Rect(
            center.X - SystemParameters.MinimumHorizontalDragDistance / 2,
            center.Y - SystemParameters.MinimumVerticalDragDistance / 2,
            SystemParameters.MinimumHorizontalDragDistance,
            SystemParameters.MinimumVerticalDragDistance);
    }

    void listBox_MouseMove(object sender, MouseEventArgs e)
    {
        if (!dragSourceGestureRect.HasValue || dragSourceGestureRect.Value.Contains(e.GetPosition(listBox)))
            return;

        dragSourceGestureRect = null;

        var data = new DataObject(DataFormats.UnicodeText, "The Data");
        DragDrop.DoDragDrop(listBox, data, DragDropEffects.Copy);

        e.Handled = true;
    }
}

我是否可以仅在左按钮上进行WPF ListBox更改选择

1 个答案: