UWP 拖放自定义 type/class

Question

你好，我正在尝试在 2 个 GridView 之间启用拖放，我设法使用 "DataPackage" class（SetText、SetBitmap 等）的自定义类型来做到这一点，但我无法弄清楚如何使用自定义 class/type 执行此操作。两个 GridView 都数据绑定到相同的自定义 class（只有几个属性、int、字符串、位图图像），我只是想直接将这些数据项从一个 GridView 拖到另一个。非常感谢您的帮助！

Answer 1

我遇到了同样的问题，请检查这个示例我使用了 Behaviors，因为我使用了 MVVM 模式，但我为 ListView 做了这个，但对于 GridView 也一样，只是做了一些小的改动。

将行为 <ListView> 更改为 <GridView>

此行为附加在您要拖动项目的 ListView 中

public class StartingDragBehavior:Behavior<ListView>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        this.AssociatedObject.CanDragItems = true;
        this.AssociatedObject.DragItemsStarting += AssociatedObject_DragItemsStarting;
    }


    private void AssociatedObject_DragItemsStarting(object sender, DragItemsStartingEventArgs e)
    {
        e.Data.RequestedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Copy;
        if(e.Items!=null && e.Items.Any())
        {
            e.Data.Properties.Add("item", e.Items.FirstOrDefault());

        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        this.AssociatedObject.DragItemsStarting -= AssociatedObject_DragItemsStarting;

    }
}

此行为附加在您要放置项目的 ListView 中这里有另一个 Behavior 来捕获 drop 事件。

public class EndDropBehavior : Behavior<ListView>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        this.AssociatedObject.AllowDrop = true;
        this.AssociatedObject.Drop += AssociatedObject_Drop;
        this.AssociatedObject.DragOver += AssociatedObject_DragOver;
    }

    private void AssociatedObject_Drop(object sender, Windows.UI.Xaml.DragEventArgs e)
    {
        if (e.DataView != null &&
            e.DataView.Properties != null &&
            e.DataView.Properties.Any(x => x.Key == "item" && x.Value.GetType() == typeof(MyObject)))
        {
            try
            {
                var def = e.GetDeferral();

                var item = e.Data.Properties.FirstOrDefault(x => x.Key == "item");
                var card = item.Value as MyObject;


                    var list = sender as ListView;
                    var vm = list.DataContext as Infrastructure.ViewModels.CreditCardsViewModel;


                        vm.MyCollection.Add(card);

                def.Complete();
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.ToString());

            }

        }
        else
        {
            e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.None;
        }
    }

    private void AssociatedObject_DragOver(object sender, Windows.UI.Xaml.DragEventArgs e)
    {
        if (e.DataView != null &&
            e.DataView.Properties != null &&
            e.DataView.Properties.Any(x => x.Key == "item" && x.Value.GetType() == typeof(MyObject)))
        {

            e.AcceptedOperation = e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Copy;

        }
        else
        {
            e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.None;
        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        this.AssociatedObject.Drop -= AssociatedObject_Drop;

        this.AssociatedObject.DragOver -= AssociatedObject_DragOver;
    }
}

如果您不使用 MVVM 模式，只需检查行为的事件。

Answer 2

所以总结一下，为了其他人的利益，我将这些添加到 DataTemplate 内容的事件处理程序中，因为我只希望特定 (ViewModel) 类型的项目可以拖动。

    private void Grid_Drop(object sender, DragEventArgs e)
    {
        if (sender is FrameworkElement)
        {
            var fe = sender as FrameworkElement;
            var targetIvm = fe.DataContext as ItemViewModel;
            object obj = null;
            if(e.DataView.Properties.TryGetValue("ItemViewModel", out obj))
            {
                var sourceIvm = obj as ItemViewModel;
                vm.MoveItem(sourceIvm, targetIvm);
            }
        }
    }

    private void Grid_DragStarting(Windows.UI.Xaml.UIElement sender, DragStartingEventArgs args)
    {
        if (sender is FrameworkElement)
        {
            var fe = sender as FrameworkElement;
            var item = new KeyValuePair<string, object>("ItemViewModel", fe.DataContext);
            args.Data.RequestedOperation = DataPackageOperation.Move;
            args.Data.Properties.Add("ItemViewModel", fe.DataContext);
        }
    }

UWP 拖放自定义 type/class

UWP drag and drop custom type/class

c#

drag-and-drop

win-universal-app