UWP拖拽操作中DragEnter与DragOver事件未触发问题求助

我正在开发Windows平台的UWP桌面应用，实现拖拽功能时遇到异常：拖拽文件时始终显示禁止符号🚫，DragEnter和DragOver事件似乎未触发。未以管理员身份运行Visual Studio 2022，求解决。

相关代码 #

MainPage.xaml.cs #

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

namespace XML2PDFConverter
{
    /// <summary>
    /// Starting from a blank page.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        private void BackgroundGrid_DragEnter(object sender, DragEventArgs e)
        {
            e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Move;
        }

        private async void BackgroundGrid_Drop(object sender, DragEventArgs e)
        {
            if (e.DataView.Contains(Windows.ApplicationModel.DataTransfer.StandardDataFormats.StorageItems))
            {
                var items = await e.DataView.GetStorageItemsAsync();
                var filePaths = items.Select(x => x.Path).ToList();
            }
        }

        private void BackgroundGrid_DragOver(object sender, DragEventArgs e)
        {
            e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Move;
        }
    }
}

MainPage.xaml #

<Page
    x:Class="XMLToPDFConverter.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="XMLToPDFConverter"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <Grid x:Name="BackgroundGrid" AllowDrop="True" DragEnter="BackgroundGrid_DragEnter" Drop="BackgroundGrid_Drop" DragOver="BackgroundGrid_DragOver" />
</Page>

解决方法 #

• 修正命名空间不一致问题：后台代码命名空间是XML2PDFConverter，但XAML的x:Class是XMLToPDFConverter（注意2和To的差异），这会导致XAML与后台代码无法绑定，事件无法触发。需保持两者命名空间完全一致。
• 设置Grid有效尺寸：当前Grid未指定宽高，可能实际尺寸为0导致无法捕获拖拽事件。给Grid添加尺寸属性，确保它占据页面空间：

  <Grid x:Name="BackgroundGrid" AllowDrop="True" DragEnter="BackgroundGrid_DragEnter" Drop="BackgroundGrid_Drop" DragOver="BackgroundGrid_DragOver" 
        Width="Auto" Height="Auto" />
  

• 调整拖拽操作类型：如果是复制文件，建议将AcceptedOperation设为Copy而非Move，避免系统权限限制；同时可在DragOver事件中隐藏默认禁止符号：

  private void BackgroundGrid_DragOver(object sender, DragEventArgs e)
  {
      e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Copy;
      e.DragUIOverride.IsGlyphVisible = false;
  }
  

• 添加文件访问权限：若拖拽文件位于Documents、Downloads等受保护目录，需在Package.appxmanifest中添加对应权限（如Documents Library或Downloads Library）。

内容的提问来源于stack exchange，提问作者Wt.N