在 UWP 上完成拖放时，不会触发 Enter 或 over 事件

Question

I'm making a desktop app with UWP for Windows. I was making drag and drop features, but it doesn't work. When I drag a file, it keeps showing "Not allowed" symbol,. Drag events and over events seem not to be fired. Any help is greatly appreciated. I'm not running Visual Studio 2022 as an admin.

Mainpage.xamc.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>

Answer 1

The problem is, that your grid does not have a background color. It is enought to set the background color to transparent and it will work as expected:

<Grid x:Name="BackgroundGrid" Background="Transparent" AllowDrop="True" DragEnter="BackgroundGrid_DragEnter" Drop="BackgroundGrid_Drop" DragOver="BackgroundGrid_DragOver" />